Histopathology 2015, 66, 37–48. DOI: 10.1111/his.12565
REVIEW
Current issues in inflammatory bowel disease neoplasia Michael Vieth & Helmut Neumann1 Institute of Pathology, Klinikum Bayreuth, Bayreuth, Germany, and 1Department of Medicine 1, University Hospital Erlangen, Erlangen, Germany
Vieth M, Neumann H (2015) Histopathology 66, 37–48. DOI: 10.1111/his.12565
Current issues in inflammatory bowel disease neoplasia Recent histological criteria and developments in the field of endoscopic imaging have led to higher detection rates of neoplasms in ulcerative colitis. Once a lesion is detected, endoscopic resection is recommended to guide subsequent surveillance or therapy and to gain adequate material for histological diagnosis. Further management is based on the grade of neoplasia and on whether the neoplasia is categorized
as sporadic or colitis-associated. Nevertheless it may sometimes be difficult to distinguish colitis-associated neoplasms from sporadic neoplasms. A better way to report this may be ultimately classified. Here, we review endoscopic and histological parameters to help to differentiate colitis-associated neoplasia from sporadic lesions and discuss pathogenesis and therapeutic options.
Keywords: adenoma-like lesion or mass, advanced endoscopic imaging, carcinogenesis, dysplasia-associated lesion or mass, endocytoscopy, endomicroscopy, histology, neoplasia, raised lesion with dysplasia, ulcerative colitis
Introduction Not long ago, the clinical relevance of histology in chronic inflammatory bowel disease was restricted mainly to a few questions, such as: 1. Is this really chronic inflammatory bowel disease (IBD)? 2. Are we dealing with Crohn’s disease or ulcerative colitis (UC)? 3. Can we exclude dysplasia? 4. Can we exclude a carcinoma? More recently, the clinical questions have become much more complex for gastroenterologists and pathologists: in particular, it is of clinical importance to distinguish sporadic colorectal neoplasia from colitis-associated neoplasia (DALM: dysplasia-associated lesion or mass) and offer medical, endoscopic or surgical treatment from an enormous variety of treatment options (Figure 1).1 Close interaction of the different Address for correspondence: M Vieth, Institute of Pathology, Klinikum Bayreuth, Preuschwitzerstrasse 101, 95445 Bayreuth, Germany. e-mail: [email protected] © 2015 John Wiley & Sons Ltd.
subspecialities is thought to provide the optimal treatment. Moreover, different pathways in the development of sporadic neoplasia and neoplasia in ulcerative colitis have been shown (Figure 2). During the last few years, several terms emerged that were introduced in an attempt to characterize more clearly all possible endoscopic and histological appearances. However, many of these new additional terms, such as adenomalike lesion or mass (ALM) or raised lesion with dysplasia (RLD) have served only to confuse clinicians and pathologists alike. Furthermore, the clinical relevance of these new terms is not entirely clear (Table 1). The term RLD was suggested at a consensus conference of the European Crohn’s and Colitis Organization (ECCO) to replace other terms and to underscore that, in some instances, it can be difficult to separate sporadic and colitis-associated neoplasia.2,3 However, RLD is itself also a rather ill-defined term. Furthermore, ulcerative colitis-associated neoplasms are not necessarily raised, but can have a depressed morphology or even show growth within the mucosal layer. Therefore, in our opinion, the term RLD does not offer any advantage over the existing terminology,
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C a r c i n o m a
HGD / HG IEN LGD / LG IEN
HGD / HG IEN LGD / LG IEN
sporadic adenoma
colitis-associated neoplasia
Figure 1. Concepts of diagnosis of adenoma versus sporadic adenoma (LGD, low-grade dysplasia; LG IEN, low-grade intraepithelial neoplasia; HGD, high-grade dysplasia; HG IEN, high-grade intraepithelial neoplasia) (modified after Vieth and Neumann18).
Neoplasia
sporadic carcinoma aneuploidy methylation MSI K-ras COX-2
APC
early adenoma
normal epithelium
DCC/DPC4
intermediate adenoma
p53
late adenoma
carcinoma
colitis-associated carcinoma p53 mut.
aneuploidy CIN/MSI methylation COX-2
normal epithelium
p53 LOH
suspicious for neoplasia
DCC/DPC4
APC
K-ras
low grade IEN/dysplasia
high grade IEN/dysplasia
carcinoma
Figure 2. Differences in pathways for sporadic carcinoma compared to colitis-associated carcinoma (LGD, low-grade dysplasia; LG IEN, low-grade intraepithelial neoplasia; HGD, high-grade dysplasia; HG IEN, high-grade intraepithelial neoplasia) (modified after Vieth and Neumann18 and Itzkowitz and Yio51).
namely sporadic adenoma or colitis-associated neoplasia (DALM). Criteria to distinguish sporadic lesions from colitisassociated neoplastic lesions have been described in the literature (Table 2) and are discussed in more detail below. Essentially, no single criterion should be applied in isolation and all criteria must be taken into account
consistently for a diagnosis of any given lesion. In most routine cases, using the criteria described in Table 2 allows distinction between sporadic adenomas and colitis-associated lesions with an acceptable precision.4 Therefore, we would not encourage the use of the new terms until clinical relevance can be shown to be superior to that of the existing terms. © 2015 John Wiley & Sons Ltd, Histopathology, 66, 37–48.
Colitis neoplasia
Improvements in endoscopic imaging and accumulated experience in histopathology have resulted in the improved detection of lesions during the past 10 years.5–7
39
Data from the Institute of Pathology in Bayreuth show a clear increase of low-grade lesions, both sporadic adenomas and colitis-associated, compared to data from 10 years ago (Figure 3) within the same
Table 1. History of development of neoplasia terminology for lesions in patients with and without inflammatory bowel disease (IBD). Until the 1990s all neoplastic lesions in IBD were simply summarized as dysplasia-associated lesion or mass (DALM), with no subclassification into colitis-associated or sporadic. From the 1990s onwards grading into colitis-associated neoplasms and sporadic neoplasms were undertaken. Invasive carcinomas were never subclassified into sporadic versus colitis-associated. From 2005 onwards sporadic adenomas were labelled as adenoma-like lesion or mass (ALM). From 2010 onwards, due to inconsistencies at some centres, gastroenterologists tended to use the term ALM for sharply delineated, polypoid lesions regardless of whether sporadic or colitis-associated, leading to the term ALM-like DALM. Gastroenterologists were further confused and learned that pathologists showed a poor interobserver agreement on the question of whether neoplasia is colitis-associated or sporadic, and thought that a new term should serve their needs without being confused by too many different terms in histopathology, and proposed the term raised lesion with dysplasia (RLD) to replace all other terms they could not rely upon at all centres. In fact, the most logical approach is without doubt the approach (b) [as an add-on to the original approach (a)] that was started from the 1990s, stating clearly whether a lesion is sporadic or colitis-associated, and this is clinically relevant. (a) Until the 1990s DALM Low-grade dysplasia/high-grade dysplasia Invasive carcinoma in IBD (b) From 1990 onwards Colitis-associated
Sporadic
DALM
Adenoma (low-grade)
Low-grade dysplasia/high-grade dysplasia
Adenoma (high-grade)
Invasive carcinoma in IBD (c) From 2005 onwards Colitis-associated
Sporadic
DALM
Adenoma (low-grade) (ALM LGD)
Low-grade dysplasia/high-grade dysplasia
Adenoma (high-grade) (ALM HGD)
Invasive carcinoma in IBD (d) From 2010 onwards Colitis-associated
Sporadic
DALM
Adenoma (low-grade) (ALM LGD)
Low-grade dysplasia/high-grade dysplasia
Adenoma (high-grade) (ALM HGD)
ALM-like DALM Low-grade dysplasia/high-grade dysplasia Invasive carcinoma in IBD (e) From 2012 onwards RLD Low-grade dysplasia/high-grade dysplasia Invasive carcinoma in IBD © 2015 John Wiley & Sons Ltd, Histopathology, 66, 37–48.
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Table 2. Criteria in favour of colitis-associated neoplasia rather than sporadic adenoma (modified after Vieth et al.4) Clinical information Younger age at diagnosis of neoplasia Longer duration of colitis Increased extent of colitis Unsharply delineated lesion Gross description other than sharply delineated and polypoid Histological criteria Distorted crypt architecture with branching and fissuring Varying diameter and size of glands Mucin vacuoles with lost polarity Proliferation zone over the whole epithelial thickness Prominent hyperchromatic and pleomorphic nuclei Stromal tissue with irregular infiltration by inflammatory cells within a loose matrix
stable patient cohort that was derived consecutively from the cases sent for routine histology to the Institute of Pathology in Bayreuth. Notably, the number of high-grade lesions and carcinomas has not changed during the past 10 years. It can be speculated that the number of detected lowgrade lesions (Figures 4–6) increased due to improved methods, whereas the stable number of high-grade lesions (Figure 7) or carcinomas have not yet decreased because the majority of low-grade lesions belong to a prevalent group that is currently more likely to be detected. A decrease in colitis-associated neoplasia, due to both improved detection and therapy, including improved anti-inflammatory treatments that disrupt the colitis–carcinogenesis sequence more efficiently, is anticipated in the near future in our population, but we have yet to observe it.8,9 This is in contrast to the long-term follow-up data reported by Rutter et al.10 during a 30-year period that clearly show a decrease of the prevalence of neoplastic lesions in ulcerative colitis in that long-term study cohort. Our follow-up period may simply be too short to see marked changes in the prevalent numbers of affected individuals.
Diagnostic criteria ENDOSCOPY
Endoscopically, lesions in IBD may appear either polypoid or non-polypoid11 (Figure 8). While it is not
70
2001 2011
60 50 40 30 20 10 0 adenoma
LGD/LG IEN
HGD/HG IEN
carcinoma
Figure 3. Frequency of sporadic adenomas versus colitis associated neoplasms at Klinikum Bayreuth 2001 versus 2011 (LGD, lowgrade dysplasia; LG IEN, low-grade intraepithelial neoplasia; HGD, high-grade dysplasia; HG IEN, high-grade intraepithelial neoplasia) (modified after Vieth and Neumann18).
difficult to define polypoid lesions, there has been inconsistency in the literature regarding the definition of non-polypoid lesions (also called flat lesions).3 Some studies describe flat lesions as lesions that are not detectable using conventional white-light endoscopy, while others also include slightly raised areas of the mucosa.12,13 According to the recent European evidence-based consensus on the diagnosis and © 2015 John Wiley & Sons Ltd, Histopathology, 66, 37–48.
Colitis neoplasia
41
A
B
Figure 5. Histological image of a sporadic adenoma in ulcerative colitis (UC) in remission with slight crypt distortion of the adjacent mucosa. Non-neoplastic glands can be found within the area of dysplasia in sporadic adenomas, and this is not a good marker for UC-associated neoplasia.
Figure 4. A, Central so-called clear cell dysplasia in ulcerative colitis (UC) with numerous dysplastic goblet cells with markedly distorted cellular architecture and shape (haematoxylin and eosin (H&E). B, Solid-appearing so-called clear cell dysplasia in UC combined with conventional colitis-associated low-grade dysplasia.
management of ulcerative colitis, flat lesions are defined as endoscopically undetectable, whereas raised dysplasia refers to any type of endoscopically detectable lesions.13 Additional endoscopic contrast enhancement is strongly recommended, especially chromoendoscopy, with low percentages of methylene blue to both increase detection and realize the delineation of a certain lesion. Raised lesions are divided into sporadic adenomas, also called adenoma-like lesions (ALM) and colitis-associated lesions (DALM). ALM lesions can constitute any types of polyp, including pedunculated and sessile, and can normally be resected using standard polypectomy techniques. In contrast, non-adenoma-like lesions include velvety patches, plaques, irregular bumps © 2015 John Wiley & Sons Ltd, Histopathology, 66, 37–48.
Figure 6. Histological image of low-grade colitis-associated neoplasia/dysplasia.
and nodules, wart-like thickenings, stricturing lesions and broad-based masses.3 Accordingly, it is often challenging to remove those lesions using standard snare polypectomy.14 On a practical note, lesions arising proximal to the macroscopic and microscopic involvement of the chronic inflammation are readily considered as sporadic adenomas and should therefore be treated by standard polypectomy techniques.3 In patients with numerous post-inflammatory polyps it can be extremely difficult to detect a neoplastic lesion (Figure 9).
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Figure 7. High-grade dysplasia in ulcerative colitis with marked nuclear pleomorphism. Nuclei have lost their polarity, and are no longer elongated as in low-grade dysplasia but are, instead, round to oval nuclei with beginning cribriforme gland formation.
Figure 9. Multiple inflammatory and post-inflammatory polyps in a patient with long-standing ulcerative colitis. Surveillance endoscopy is a particular challenge in these patients.
IBD recommends pan-colonic methylene blue or indigo carmine dye spraying during surveillance colonoscopy with targeted biopsies of any visible lesion.17 Even if chromoendoscopy is not available, four random biopsies should be performed every 10 cm.17 Importantly, biopsies should be submitted to the pathologist in separate jars to assign any detected dysplasia to the appropriate colon segment for subsequent treatment.18 HISTOPATHOLOGY
Figure 8. Flat lesion in patient with long-standing ulcerative colitis that became obvious during surveillance colonoscopy after dyespraying with methylene blue. These lesions should be resected in toto using standard polypectomy techniques.
The development of advanced endoscopic imaging techniques has led to an increased detection of neoplastic lesions in IBD.15 In this context, it has been shown that chromoendoscopy-guided (methylene blue 0.1%) confocal laser endomicroscopy (CLE) could detect 4.75fold more neoplasia than conventional white-light endoscopy (P = 0.005).16 Thus, chromoendoscopyguided CLE may lead to significant improvements in the clinical management of long-standing ulcerative colitis. As CLE is not routinely available, the recent European evidence-based consensus for endoscopy in
The diagnosis of neoplasia in ulcerative colitis is challenging; sometimes, even correlation with the endoscopic impression does not facilitate interpretation. For example, so-called clear cell dysplasia can be subtle to recognize as neoplastic (Figure 4A,B). In earlier series it was believed that an endoscopic lesion was noted in only 20–50% of neoplasms.4,6 From our routine cases we have some examples of carcinomas that were due to their high differentiation indistinguishable from a low-grade lesion but just recognized as carcinomas, as they were invasive. Differentiating sporadic neoplasia (Figure 5) from colitis-associated neoplasia (Figures 6–7) is difficult, but possible. In biopsies, differential diagnosis can be challenging.6 However, in our own series we were able to demonstrate that there are differences in the clinical data of patients that were diagnosed as with sporadic adenoma versus those with colitis-associated lesions (Table 3).4,6,9 For the pathologist, it is also crucial to obtain a copy of the endoscopy report to determine whether with the biopsy being evaluated is from a sharply © 2015 John Wiley & Sons Ltd, Histopathology, 66, 37–48.
Colitis neoplasia
delineated polypoid lesion (sporadic adenoma) or from a poorly marginated lesion that can be flat, irregular, focally polypoid or even slightly depressed (colitisassociated lesion).4,6,9 Our group developed criteria in the early 1990s to differentiate sporadic adenoma from colitis-associated neoplasms6 that have largely stood the test of time. They are outlined below, with some refinements. However, it should be realized that none of the criteria have been really validated nor tested for specificity and sensitivity. Therefore, all criteria (but not a single criterion) can be used to enhance the probability of a correct distinction of colitis-associated dysplasia versus a sporadic adenoma. Due to missing alternatives, these criteria are widely used. Using complicated terminology for differentiating sporadic adenoma and colitis-associated lesions should be avoided. Similarly, attempting more pragmatic concepts to simplify the situation by diagnosing all such lesions as ‘raised dysplasia’ is too simple, even if the therapeutic regimen for sporadic adenomas and colitis-associated neoplasia is the same; namely, endoscopic resection when the lesion can be completely resected and no carcinomatous component is found. It should be taken into account that patients who have multiple neoplasms or multiple post-inflammatory polyps cannot be safely followedup and thus surgical treatment needs to be considered even in the absence of high-grade dysplasia or carcinoma. Microscopically, sporadic adenomas show the so-called top–down morphology, whereas colitisassociated neoplasms are believed to show a bottomup morphology, beginning at the base of the mucosa and covering the whole height of the mucosa.1 Spe-
Table 3. Differences in clinical data for sporadic adenomas versus colitis-associated neoplasia (modified after Vierth et al.4,6 and Vieth and Tannapfel9) Adenoma Age (years)
DALM
43
cial stains such as p53 or ki67 can help in some cases, but not definitively in all. The authors of this paper prefer not to use special stains, as their interpretation is also hampered by huge interobserver variation. Sporadic adenomas are thought to be less positive for ki67 and stain less intensely for p53, but the overlap is high and negativity does not exclude anything, especially in p53.
Differential diagnosis GLANDS
Adenomatous glands are normally round or oval, regular in shape, with comparable diameters and regular configuration. Colitis-associated neoplasms show irregular glandular configuration, shape and diameter. MUCIN VACUOLES
Adenomas show regular mucin vacuoles in configuration and size that are located mainly in the apical portion of the epithelial cells. In colitis-associated neoplasms the configuration of mucin vacuoles, including their diameter, varies and vacuoles are distributed irregularly throughout the epithelium. More often, so-called dystrophic goblet cells can be seen. NUCLEI
Adenomatous nuclei are hyperchromatic and elongated and arranged in a palisading fashion, with regular configuration and diameter with moderately dense chromatin. In colitis-associated neoplasms nuclei are round to oval, less densely packed and irregular in diameter and in configuration. Localization of nuclei in colitis-associated neoplasms is more irregular than in sporadic adenomas. Often the nuclear hyperchromasia is variable, including vesicular nuclei with marginal nuclei.
66
43
7
12
STROMA
Single lesions, %
65
35
Pancolitis, %
47
88
Euploidy, %
100
26
There is consistently scant loose stromal tissue in between adenomatous glands, whereas in colitis-associated neoplasms there are irregular dense stromal tissue bands.
4
40
76
30
Duration of colitis (years)
p53 mutation, %
PROLIFERATION ZONE
bcl-2 expression, %
DALM, Dysplasia-associated lesion or mass. © 2015 John Wiley & Sons Ltd, Histopathology, 66, 37–48.
In adenomas, the proliferation zone starts at the luminal/apical part of the mucosa, with early devel-
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opment of endoscopically recognizable small knobs. The proliferation zone in colitis-associated lesions is localized at the base of the mucosa. Neoplastic epithelia proliferate up to the surface. Horizontal tubular proliferations of the crypts at the base are typical for colitis-associated neoplasms. In our experience, the presence of intermingling of neoplastic and non-neoplastic glands is not a reliable criterion to distinguish colitis-associated neoplasia from sporadic adenoma. DELINEATION FROM SURROUNDING MUCOSA
Adenomatous lesions show a sharp delineation, whereas colitis-associated neoplasms almost always show an irregular delineation that can also be visualized endoscopically with dye staining. The differential diagnosis can only be reached when all criteria are taken into account. These include clinical data such as age, duration of disease and endoscopic findings. The use of a single criterion without taking all the other criteria into the diagnosis has to be strictly avoided. Lesions that cannot be diagnosed safely as sporadic adenoma should be considered as colitis-associated lesion to avoid under diagnosis.
Pathogenesis The development of colorectal neoplasia in ulcerative colitis requires a multistep sequence of genetic, epigenetic and microbiological factors.19–22 Sporadic carcinomas follow the adenoma–carcinoma sequence, whereas in ulcerative colitis this sequence is initiated by the inflammation itself, leading to an inflammation–dysplasia–carcinoma sequence. Therefore, these individuals have two different types of neoplasms: sporadic neoplasia (adenoma) and colitis-associated neoplasia9,18 (Figure 1). Sporadic adenomas in patients with ulcerative colitis are equal to those in individuals without ulcerative colitis.1,9 Chronic inflammation in patients with ulcerative colitis increases the risk of developing neoplasms.23,24 In patients with ulcerative colitis this inflammation is mainly a T helper type 2 (Th2)-like immune response.21,22 In Crohn’s disease, a Th1/Th17 immune response with typically increased production of interferon (IFN)-c is observed. Long-standing epithelial interaction with cytokines leads to oxidative stress and release of reactive nitrogen and oxygen metabolites with mutagenic effects.19 Early events in colitis-associated neoplasms include aneuploidy and chromosomal aberrations that can be detected by DNA cytometry even earlier than the
histologically visible alterations (c. 6 months), followed by p53 mutation and other epigenetic changes such as hypermethylation25 (Table 3, Figure 2). Some data point to aberrant promotor methylation of p14ARF, p16INK4 and oestrogen receptor genes in patients with ulcerative colitis.26–28 Recent data also indicated the involvement of interleukin (IL)-6, IL-1b, tumour necrosis factor (TNF)-a and IFN-c.21 Further steps in colitis-associated carcinogenesis include chromosomal losses on chromosomes 7, 17 and 18 [the so-called transforming growth factor (TGF)-b pathway] and an increase of genomic instability towards invasive carcinoma.20 Mutations often found in sporadic carcinoma, such as Kirsten rat sarcoma viral oncogene homologue (KRAS) and adenomatous polyposis coli (APC), can also be detected in colitis-associated neoplasia in a subset (fewer than 30%) of the cases.29 Figure 2 shows the various pathways with differences in sporadic carcinoma compared to colitis-associated carcinoma. It should be noted that morphological distinction between sporadic carcinoma and colitis-associated carcinoma is not possible, although squamous cell carcinoma and signet ring cell carcinoma are more likely as colitisassociated carcinomas. MICROSATELLITE INSTABILITY
Recent data are not conclusive concerning microsatellite instability (MSI) in neoplasms in ulcerative colitis. In a somewhat small study cohort, Japanese data indicated a significant accumulation of MSI depending on grade of neoplasia, duration and severity of inflammation.30 Other Asian studies failed to show such an accumulation, but clearly showed that p53 mutations are early events whereas KRAS mutations appear to be late events in ulcerative colitis carcinogenesis.31 Currently, MSI studies are not useful in the detection of neoplasms nor are they helpful in differentiating sporadic neoplasms from ulcerative colitisassociated neoplasms. It is possible that the initial Japanese study was biased by a population phenomenon that led to a selection of patients with MSI.30 OXIDATIVE STRESS
Oxidative stress leads to epithelial damage that fuels the pathogenesis of colitis and probably also promotes carcinogenesis. Reactive oxygen and nitrogen species (RONS) are implicated in these effects and are released by the immune system itself.32,33 Free radicals can influence numerous metabolic processes and thus actively alter processes in DNA, RNA and pro© 2015 John Wiley & Sons Ltd, Histopathology, 66, 37–48.
Colitis neoplasia
tein regulation. Carcinogenesis can be promoted if genes such as p53 are involved, which are responsible for the homeostasis of colonocytes.34 Many data implicate oxidative stress as being responsible for early p53 mutations in ulcerative colitis and late APC and KRAS mutations (
REVIEW
Current issues in inflammatory bowel disease neoplasia Michael Vieth & Helmut Neumann1 Institute of Pathology, Klinikum Bayreuth, Bayreuth, Germany, and 1Department of Medicine 1, University Hospital Erlangen, Erlangen, Germany
Vieth M, Neumann H (2015) Histopathology 66, 37–48. DOI: 10.1111/his.12565
Current issues in inflammatory bowel disease neoplasia Recent histological criteria and developments in the field of endoscopic imaging have led to higher detection rates of neoplasms in ulcerative colitis. Once a lesion is detected, endoscopic resection is recommended to guide subsequent surveillance or therapy and to gain adequate material for histological diagnosis. Further management is based on the grade of neoplasia and on whether the neoplasia is categorized
as sporadic or colitis-associated. Nevertheless it may sometimes be difficult to distinguish colitis-associated neoplasms from sporadic neoplasms. A better way to report this may be ultimately classified. Here, we review endoscopic and histological parameters to help to differentiate colitis-associated neoplasia from sporadic lesions and discuss pathogenesis and therapeutic options.
Keywords: adenoma-like lesion or mass, advanced endoscopic imaging, carcinogenesis, dysplasia-associated lesion or mass, endocytoscopy, endomicroscopy, histology, neoplasia, raised lesion with dysplasia, ulcerative colitis
Introduction Not long ago, the clinical relevance of histology in chronic inflammatory bowel disease was restricted mainly to a few questions, such as: 1. Is this really chronic inflammatory bowel disease (IBD)? 2. Are we dealing with Crohn’s disease or ulcerative colitis (UC)? 3. Can we exclude dysplasia? 4. Can we exclude a carcinoma? More recently, the clinical questions have become much more complex for gastroenterologists and pathologists: in particular, it is of clinical importance to distinguish sporadic colorectal neoplasia from colitis-associated neoplasia (DALM: dysplasia-associated lesion or mass) and offer medical, endoscopic or surgical treatment from an enormous variety of treatment options (Figure 1).1 Close interaction of the different Address for correspondence: M Vieth, Institute of Pathology, Klinikum Bayreuth, Preuschwitzerstrasse 101, 95445 Bayreuth, Germany. e-mail: [email protected] © 2015 John Wiley & Sons Ltd.
subspecialities is thought to provide the optimal treatment. Moreover, different pathways in the development of sporadic neoplasia and neoplasia in ulcerative colitis have been shown (Figure 2). During the last few years, several terms emerged that were introduced in an attempt to characterize more clearly all possible endoscopic and histological appearances. However, many of these new additional terms, such as adenomalike lesion or mass (ALM) or raised lesion with dysplasia (RLD) have served only to confuse clinicians and pathologists alike. Furthermore, the clinical relevance of these new terms is not entirely clear (Table 1). The term RLD was suggested at a consensus conference of the European Crohn’s and Colitis Organization (ECCO) to replace other terms and to underscore that, in some instances, it can be difficult to separate sporadic and colitis-associated neoplasia.2,3 However, RLD is itself also a rather ill-defined term. Furthermore, ulcerative colitis-associated neoplasms are not necessarily raised, but can have a depressed morphology or even show growth within the mucosal layer. Therefore, in our opinion, the term RLD does not offer any advantage over the existing terminology,
38
M Vieth & H Neumann
C a r c i n o m a
HGD / HG IEN LGD / LG IEN
HGD / HG IEN LGD / LG IEN
sporadic adenoma
colitis-associated neoplasia
Figure 1. Concepts of diagnosis of adenoma versus sporadic adenoma (LGD, low-grade dysplasia; LG IEN, low-grade intraepithelial neoplasia; HGD, high-grade dysplasia; HG IEN, high-grade intraepithelial neoplasia) (modified after Vieth and Neumann18).
Neoplasia
sporadic carcinoma aneuploidy methylation MSI K-ras COX-2
APC
early adenoma
normal epithelium
DCC/DPC4
intermediate adenoma
p53
late adenoma
carcinoma
colitis-associated carcinoma p53 mut.
aneuploidy CIN/MSI methylation COX-2
normal epithelium
p53 LOH
suspicious for neoplasia
DCC/DPC4
APC
K-ras
low grade IEN/dysplasia
high grade IEN/dysplasia
carcinoma
Figure 2. Differences in pathways for sporadic carcinoma compared to colitis-associated carcinoma (LGD, low-grade dysplasia; LG IEN, low-grade intraepithelial neoplasia; HGD, high-grade dysplasia; HG IEN, high-grade intraepithelial neoplasia) (modified after Vieth and Neumann18 and Itzkowitz and Yio51).
namely sporadic adenoma or colitis-associated neoplasia (DALM). Criteria to distinguish sporadic lesions from colitisassociated neoplastic lesions have been described in the literature (Table 2) and are discussed in more detail below. Essentially, no single criterion should be applied in isolation and all criteria must be taken into account
consistently for a diagnosis of any given lesion. In most routine cases, using the criteria described in Table 2 allows distinction between sporadic adenomas and colitis-associated lesions with an acceptable precision.4 Therefore, we would not encourage the use of the new terms until clinical relevance can be shown to be superior to that of the existing terms. © 2015 John Wiley & Sons Ltd, Histopathology, 66, 37–48.
Colitis neoplasia
Improvements in endoscopic imaging and accumulated experience in histopathology have resulted in the improved detection of lesions during the past 10 years.5–7
39
Data from the Institute of Pathology in Bayreuth show a clear increase of low-grade lesions, both sporadic adenomas and colitis-associated, compared to data from 10 years ago (Figure 3) within the same
Table 1. History of development of neoplasia terminology for lesions in patients with and without inflammatory bowel disease (IBD). Until the 1990s all neoplastic lesions in IBD were simply summarized as dysplasia-associated lesion or mass (DALM), with no subclassification into colitis-associated or sporadic. From the 1990s onwards grading into colitis-associated neoplasms and sporadic neoplasms were undertaken. Invasive carcinomas were never subclassified into sporadic versus colitis-associated. From 2005 onwards sporadic adenomas were labelled as adenoma-like lesion or mass (ALM). From 2010 onwards, due to inconsistencies at some centres, gastroenterologists tended to use the term ALM for sharply delineated, polypoid lesions regardless of whether sporadic or colitis-associated, leading to the term ALM-like DALM. Gastroenterologists were further confused and learned that pathologists showed a poor interobserver agreement on the question of whether neoplasia is colitis-associated or sporadic, and thought that a new term should serve their needs without being confused by too many different terms in histopathology, and proposed the term raised lesion with dysplasia (RLD) to replace all other terms they could not rely upon at all centres. In fact, the most logical approach is without doubt the approach (b) [as an add-on to the original approach (a)] that was started from the 1990s, stating clearly whether a lesion is sporadic or colitis-associated, and this is clinically relevant. (a) Until the 1990s DALM Low-grade dysplasia/high-grade dysplasia Invasive carcinoma in IBD (b) From 1990 onwards Colitis-associated
Sporadic
DALM
Adenoma (low-grade)
Low-grade dysplasia/high-grade dysplasia
Adenoma (high-grade)
Invasive carcinoma in IBD (c) From 2005 onwards Colitis-associated
Sporadic
DALM
Adenoma (low-grade) (ALM LGD)
Low-grade dysplasia/high-grade dysplasia
Adenoma (high-grade) (ALM HGD)
Invasive carcinoma in IBD (d) From 2010 onwards Colitis-associated
Sporadic
DALM
Adenoma (low-grade) (ALM LGD)
Low-grade dysplasia/high-grade dysplasia
Adenoma (high-grade) (ALM HGD)
ALM-like DALM Low-grade dysplasia/high-grade dysplasia Invasive carcinoma in IBD (e) From 2012 onwards RLD Low-grade dysplasia/high-grade dysplasia Invasive carcinoma in IBD © 2015 John Wiley & Sons Ltd, Histopathology, 66, 37–48.
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M Vieth & H Neumann
Table 2. Criteria in favour of colitis-associated neoplasia rather than sporadic adenoma (modified after Vieth et al.4) Clinical information Younger age at diagnosis of neoplasia Longer duration of colitis Increased extent of colitis Unsharply delineated lesion Gross description other than sharply delineated and polypoid Histological criteria Distorted crypt architecture with branching and fissuring Varying diameter and size of glands Mucin vacuoles with lost polarity Proliferation zone over the whole epithelial thickness Prominent hyperchromatic and pleomorphic nuclei Stromal tissue with irregular infiltration by inflammatory cells within a loose matrix
stable patient cohort that was derived consecutively from the cases sent for routine histology to the Institute of Pathology in Bayreuth. Notably, the number of high-grade lesions and carcinomas has not changed during the past 10 years. It can be speculated that the number of detected lowgrade lesions (Figures 4–6) increased due to improved methods, whereas the stable number of high-grade lesions (Figure 7) or carcinomas have not yet decreased because the majority of low-grade lesions belong to a prevalent group that is currently more likely to be detected. A decrease in colitis-associated neoplasia, due to both improved detection and therapy, including improved anti-inflammatory treatments that disrupt the colitis–carcinogenesis sequence more efficiently, is anticipated in the near future in our population, but we have yet to observe it.8,9 This is in contrast to the long-term follow-up data reported by Rutter et al.10 during a 30-year period that clearly show a decrease of the prevalence of neoplastic lesions in ulcerative colitis in that long-term study cohort. Our follow-up period may simply be too short to see marked changes in the prevalent numbers of affected individuals.
Diagnostic criteria ENDOSCOPY
Endoscopically, lesions in IBD may appear either polypoid or non-polypoid11 (Figure 8). While it is not
70
2001 2011
60 50 40 30 20 10 0 adenoma
LGD/LG IEN
HGD/HG IEN
carcinoma
Figure 3. Frequency of sporadic adenomas versus colitis associated neoplasms at Klinikum Bayreuth 2001 versus 2011 (LGD, lowgrade dysplasia; LG IEN, low-grade intraepithelial neoplasia; HGD, high-grade dysplasia; HG IEN, high-grade intraepithelial neoplasia) (modified after Vieth and Neumann18).
difficult to define polypoid lesions, there has been inconsistency in the literature regarding the definition of non-polypoid lesions (also called flat lesions).3 Some studies describe flat lesions as lesions that are not detectable using conventional white-light endoscopy, while others also include slightly raised areas of the mucosa.12,13 According to the recent European evidence-based consensus on the diagnosis and © 2015 John Wiley & Sons Ltd, Histopathology, 66, 37–48.
Colitis neoplasia
41
A
B
Figure 5. Histological image of a sporadic adenoma in ulcerative colitis (UC) in remission with slight crypt distortion of the adjacent mucosa. Non-neoplastic glands can be found within the area of dysplasia in sporadic adenomas, and this is not a good marker for UC-associated neoplasia.
Figure 4. A, Central so-called clear cell dysplasia in ulcerative colitis (UC) with numerous dysplastic goblet cells with markedly distorted cellular architecture and shape (haematoxylin and eosin (H&E). B, Solid-appearing so-called clear cell dysplasia in UC combined with conventional colitis-associated low-grade dysplasia.
management of ulcerative colitis, flat lesions are defined as endoscopically undetectable, whereas raised dysplasia refers to any type of endoscopically detectable lesions.13 Additional endoscopic contrast enhancement is strongly recommended, especially chromoendoscopy, with low percentages of methylene blue to both increase detection and realize the delineation of a certain lesion. Raised lesions are divided into sporadic adenomas, also called adenoma-like lesions (ALM) and colitis-associated lesions (DALM). ALM lesions can constitute any types of polyp, including pedunculated and sessile, and can normally be resected using standard polypectomy techniques. In contrast, non-adenoma-like lesions include velvety patches, plaques, irregular bumps © 2015 John Wiley & Sons Ltd, Histopathology, 66, 37–48.
Figure 6. Histological image of low-grade colitis-associated neoplasia/dysplasia.
and nodules, wart-like thickenings, stricturing lesions and broad-based masses.3 Accordingly, it is often challenging to remove those lesions using standard snare polypectomy.14 On a practical note, lesions arising proximal to the macroscopic and microscopic involvement of the chronic inflammation are readily considered as sporadic adenomas and should therefore be treated by standard polypectomy techniques.3 In patients with numerous post-inflammatory polyps it can be extremely difficult to detect a neoplastic lesion (Figure 9).
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Figure 7. High-grade dysplasia in ulcerative colitis with marked nuclear pleomorphism. Nuclei have lost their polarity, and are no longer elongated as in low-grade dysplasia but are, instead, round to oval nuclei with beginning cribriforme gland formation.
Figure 9. Multiple inflammatory and post-inflammatory polyps in a patient with long-standing ulcerative colitis. Surveillance endoscopy is a particular challenge in these patients.
IBD recommends pan-colonic methylene blue or indigo carmine dye spraying during surveillance colonoscopy with targeted biopsies of any visible lesion.17 Even if chromoendoscopy is not available, four random biopsies should be performed every 10 cm.17 Importantly, biopsies should be submitted to the pathologist in separate jars to assign any detected dysplasia to the appropriate colon segment for subsequent treatment.18 HISTOPATHOLOGY
Figure 8. Flat lesion in patient with long-standing ulcerative colitis that became obvious during surveillance colonoscopy after dyespraying with methylene blue. These lesions should be resected in toto using standard polypectomy techniques.
The development of advanced endoscopic imaging techniques has led to an increased detection of neoplastic lesions in IBD.15 In this context, it has been shown that chromoendoscopy-guided (methylene blue 0.1%) confocal laser endomicroscopy (CLE) could detect 4.75fold more neoplasia than conventional white-light endoscopy (P = 0.005).16 Thus, chromoendoscopyguided CLE may lead to significant improvements in the clinical management of long-standing ulcerative colitis. As CLE is not routinely available, the recent European evidence-based consensus for endoscopy in
The diagnosis of neoplasia in ulcerative colitis is challenging; sometimes, even correlation with the endoscopic impression does not facilitate interpretation. For example, so-called clear cell dysplasia can be subtle to recognize as neoplastic (Figure 4A,B). In earlier series it was believed that an endoscopic lesion was noted in only 20–50% of neoplasms.4,6 From our routine cases we have some examples of carcinomas that were due to their high differentiation indistinguishable from a low-grade lesion but just recognized as carcinomas, as they were invasive. Differentiating sporadic neoplasia (Figure 5) from colitis-associated neoplasia (Figures 6–7) is difficult, but possible. In biopsies, differential diagnosis can be challenging.6 However, in our own series we were able to demonstrate that there are differences in the clinical data of patients that were diagnosed as with sporadic adenoma versus those with colitis-associated lesions (Table 3).4,6,9 For the pathologist, it is also crucial to obtain a copy of the endoscopy report to determine whether with the biopsy being evaluated is from a sharply © 2015 John Wiley & Sons Ltd, Histopathology, 66, 37–48.
Colitis neoplasia
delineated polypoid lesion (sporadic adenoma) or from a poorly marginated lesion that can be flat, irregular, focally polypoid or even slightly depressed (colitisassociated lesion).4,6,9 Our group developed criteria in the early 1990s to differentiate sporadic adenoma from colitis-associated neoplasms6 that have largely stood the test of time. They are outlined below, with some refinements. However, it should be realized that none of the criteria have been really validated nor tested for specificity and sensitivity. Therefore, all criteria (but not a single criterion) can be used to enhance the probability of a correct distinction of colitis-associated dysplasia versus a sporadic adenoma. Due to missing alternatives, these criteria are widely used. Using complicated terminology for differentiating sporadic adenoma and colitis-associated lesions should be avoided. Similarly, attempting more pragmatic concepts to simplify the situation by diagnosing all such lesions as ‘raised dysplasia’ is too simple, even if the therapeutic regimen for sporadic adenomas and colitis-associated neoplasia is the same; namely, endoscopic resection when the lesion can be completely resected and no carcinomatous component is found. It should be taken into account that patients who have multiple neoplasms or multiple post-inflammatory polyps cannot be safely followedup and thus surgical treatment needs to be considered even in the absence of high-grade dysplasia or carcinoma. Microscopically, sporadic adenomas show the so-called top–down morphology, whereas colitisassociated neoplasms are believed to show a bottomup morphology, beginning at the base of the mucosa and covering the whole height of the mucosa.1 Spe-
Table 3. Differences in clinical data for sporadic adenomas versus colitis-associated neoplasia (modified after Vierth et al.4,6 and Vieth and Tannapfel9) Adenoma Age (years)
DALM
43
cial stains such as p53 or ki67 can help in some cases, but not definitively in all. The authors of this paper prefer not to use special stains, as their interpretation is also hampered by huge interobserver variation. Sporadic adenomas are thought to be less positive for ki67 and stain less intensely for p53, but the overlap is high and negativity does not exclude anything, especially in p53.
Differential diagnosis GLANDS
Adenomatous glands are normally round or oval, regular in shape, with comparable diameters and regular configuration. Colitis-associated neoplasms show irregular glandular configuration, shape and diameter. MUCIN VACUOLES
Adenomas show regular mucin vacuoles in configuration and size that are located mainly in the apical portion of the epithelial cells. In colitis-associated neoplasms the configuration of mucin vacuoles, including their diameter, varies and vacuoles are distributed irregularly throughout the epithelium. More often, so-called dystrophic goblet cells can be seen. NUCLEI
Adenomatous nuclei are hyperchromatic and elongated and arranged in a palisading fashion, with regular configuration and diameter with moderately dense chromatin. In colitis-associated neoplasms nuclei are round to oval, less densely packed and irregular in diameter and in configuration. Localization of nuclei in colitis-associated neoplasms is more irregular than in sporadic adenomas. Often the nuclear hyperchromasia is variable, including vesicular nuclei with marginal nuclei.
66
43
7
12
STROMA
Single lesions, %
65
35
Pancolitis, %
47
88
Euploidy, %
100
26
There is consistently scant loose stromal tissue in between adenomatous glands, whereas in colitis-associated neoplasms there are irregular dense stromal tissue bands.
4
40
76
30
Duration of colitis (years)
p53 mutation, %
PROLIFERATION ZONE
bcl-2 expression, %
DALM, Dysplasia-associated lesion or mass. © 2015 John Wiley & Sons Ltd, Histopathology, 66, 37–48.
In adenomas, the proliferation zone starts at the luminal/apical part of the mucosa, with early devel-
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opment of endoscopically recognizable small knobs. The proliferation zone in colitis-associated lesions is localized at the base of the mucosa. Neoplastic epithelia proliferate up to the surface. Horizontal tubular proliferations of the crypts at the base are typical for colitis-associated neoplasms. In our experience, the presence of intermingling of neoplastic and non-neoplastic glands is not a reliable criterion to distinguish colitis-associated neoplasia from sporadic adenoma. DELINEATION FROM SURROUNDING MUCOSA
Adenomatous lesions show a sharp delineation, whereas colitis-associated neoplasms almost always show an irregular delineation that can also be visualized endoscopically with dye staining. The differential diagnosis can only be reached when all criteria are taken into account. These include clinical data such as age, duration of disease and endoscopic findings. The use of a single criterion without taking all the other criteria into the diagnosis has to be strictly avoided. Lesions that cannot be diagnosed safely as sporadic adenoma should be considered as colitis-associated lesion to avoid under diagnosis.
Pathogenesis The development of colorectal neoplasia in ulcerative colitis requires a multistep sequence of genetic, epigenetic and microbiological factors.19–22 Sporadic carcinomas follow the adenoma–carcinoma sequence, whereas in ulcerative colitis this sequence is initiated by the inflammation itself, leading to an inflammation–dysplasia–carcinoma sequence. Therefore, these individuals have two different types of neoplasms: sporadic neoplasia (adenoma) and colitis-associated neoplasia9,18 (Figure 1). Sporadic adenomas in patients with ulcerative colitis are equal to those in individuals without ulcerative colitis.1,9 Chronic inflammation in patients with ulcerative colitis increases the risk of developing neoplasms.23,24 In patients with ulcerative colitis this inflammation is mainly a T helper type 2 (Th2)-like immune response.21,22 In Crohn’s disease, a Th1/Th17 immune response with typically increased production of interferon (IFN)-c is observed. Long-standing epithelial interaction with cytokines leads to oxidative stress and release of reactive nitrogen and oxygen metabolites with mutagenic effects.19 Early events in colitis-associated neoplasms include aneuploidy and chromosomal aberrations that can be detected by DNA cytometry even earlier than the
histologically visible alterations (c. 6 months), followed by p53 mutation and other epigenetic changes such as hypermethylation25 (Table 3, Figure 2). Some data point to aberrant promotor methylation of p14ARF, p16INK4 and oestrogen receptor genes in patients with ulcerative colitis.26–28 Recent data also indicated the involvement of interleukin (IL)-6, IL-1b, tumour necrosis factor (TNF)-a and IFN-c.21 Further steps in colitis-associated carcinogenesis include chromosomal losses on chromosomes 7, 17 and 18 [the so-called transforming growth factor (TGF)-b pathway] and an increase of genomic instability towards invasive carcinoma.20 Mutations often found in sporadic carcinoma, such as Kirsten rat sarcoma viral oncogene homologue (KRAS) and adenomatous polyposis coli (APC), can also be detected in colitis-associated neoplasia in a subset (fewer than 30%) of the cases.29 Figure 2 shows the various pathways with differences in sporadic carcinoma compared to colitis-associated carcinoma. It should be noted that morphological distinction between sporadic carcinoma and colitis-associated carcinoma is not possible, although squamous cell carcinoma and signet ring cell carcinoma are more likely as colitisassociated carcinomas. MICROSATELLITE INSTABILITY
Recent data are not conclusive concerning microsatellite instability (MSI) in neoplasms in ulcerative colitis. In a somewhat small study cohort, Japanese data indicated a significant accumulation of MSI depending on grade of neoplasia, duration and severity of inflammation.30 Other Asian studies failed to show such an accumulation, but clearly showed that p53 mutations are early events whereas KRAS mutations appear to be late events in ulcerative colitis carcinogenesis.31 Currently, MSI studies are not useful in the detection of neoplasms nor are they helpful in differentiating sporadic neoplasms from ulcerative colitisassociated neoplasms. It is possible that the initial Japanese study was biased by a population phenomenon that led to a selection of patients with MSI.30 OXIDATIVE STRESS
Oxidative stress leads to epithelial damage that fuels the pathogenesis of colitis and probably also promotes carcinogenesis. Reactive oxygen and nitrogen species (RONS) are implicated in these effects and are released by the immune system itself.32,33 Free radicals can influence numerous metabolic processes and thus actively alter processes in DNA, RNA and pro© 2015 John Wiley & Sons Ltd, Histopathology, 66, 37–48.
Colitis neoplasia
tein regulation. Carcinogenesis can be promoted if genes such as p53 are involved, which are responsible for the homeostasis of colonocytes.34 Many data implicate oxidative stress as being responsible for early p53 mutations in ulcerative colitis and late APC and KRAS mutations (
