International Journal of Surgical Pathology http://ijs.sagepub.com/
Fibroblastic Reticulum Cell Tumor of Spleen: A Case Report Zain Karim, Rajagopal Saravana, Patrick Shenjere and Fergus Reid INT J SURG PATHOL 2014 22: 447 originally published online 12 November 2013 DOI: 10.1177/1066896913509009 The online version of this article can be found at: http://ijs.sagepub.com/content/22/5/447
Published by: http://www.sagepublications.com
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509009
research-article2013
IJSXXX10.1177/1066896913509009International Journal of Surgical PathologyKarim et al
Case Report
Fibroblastic Reticulum Cell Tumor of Spleen: A Case Report
International Journal of Surgical Pathology 2014, Vol. 22(5) 447–450 © The Author(s) 2013 Reprints and permissions: sagepub.com/journalsPermissions.nav DOI: 10.1177/1066896913509009 ijs.sagepub.com
Zain Karim, MBBS1, Rajagopal Saravana, MBBS1, Patrick Shenjere, MBChB2, and Fergus Reid, MBChB1
Abstract Fibroblastic reticulum cells (FBRCs) belong to a major subtype of stromal support cells in the lymphoid system and rarely give rise to tumors. We report a case of fibroblastic reticulum cell tumor arising in the spleen. The tumor was clinically and radiologically mistaken for a metastatic deposit in the spleen. Microscopically the tumor was composed of spindle cells arranged in fascicles and storiform pattern. The cells had oval to elongated vesicular nuclei and pale eosinophilic cytoplasm with indistinct cell borders. There were admixed inflammatory cells, including large numbers of plasma cells. The tumor cells were positive for smooth muscle actin, desmin, AE1/AE3, and MNF116. They were negative for S100, CD1a, CD21, CD23, CD34, CD31, and CD35 among other markers. The morphological features and immunoprofile of this rare tumor in comparison to the few cases reported in the literature are discussed along with the positive reaction with cytokeratins and their relationship to the smaller subset of FBRCs, the cytokeratin-positive interstitial reticulum cells in the spleen. Keywords fibroblastic reticulum (reticular) cell, cytokeratin-positive interstitial reticulum cells, spleen
Introduction
Case Description
Fibroblastic reticulum cells of lymphoid tissue are regarded as a major subtype of dendritic cells that are the group of accessory cells providing structural and functional support to the immune system. The other subtypes of this group are the follicular dendritic cells and interdigitating dendritic cells. The latter 2 subtypes have been widely described in the literature with many studies characterizing the morphology and immunophenotype of these cells including tumors arising from them. There have been fewer reports of tumors arising from fibroblastic reticular cells. Their morphological features and immunophenotype have been less extensively studied as compared to the tumors arising from follicular dendritic cells (FDCT) and interdigitating dendritic cells (IDCT). We report a case of fibroblastic reticular cell tumor of the spleen that was mistaken for a metastatic deposit and discuss the morphological features and immunoprofile of these rare tumors with an aim to raise awareness of these tumors and also help in further clarifying the behavior of these tumors. We would also wish to draw attention to the smaller subset of fibroblastic reticular cells, the cytokeratin-positive interstitial reticulum cells, which are rare as a cause of tumors in the lymphoid system.
Clinical Features A 62-year-old Caucasian man presented to the Department of Surgery due to a family history of multiple familial gastrointestinal tract malignancies. He himself was completely symptom free, denying abdominal pain, rectal bleeding, changes in bowel habit, unexplained weight loss, or indeed any other features to suggest an underlying pathological process. Examination was unremarkable, and appropriate blood tests were all within normal limits. A colonoscopic examination showed 4 polyps in the descending colon and an area in the rectum suspicious for malignancy. Computed tomography and magnetic resonance imaging scans demonstrated a 20 × 27 mm low rectal tumor (T2, N0, Mx) and a bulky spleen (137 mm) with
1
Stepping Hill Hospital, Stockport, UK Christie Hospital, Manchester, UK
2
Corresponding Author: Zain Karim, Department of Surgery, Stepping Hill Hospital, Poplar Grove, Hazel Grove, Stockport SK2 7JE, UK. Email: [email protected]
Downloaded from ijs.sagepub.com at UNIV OF WINNIPEG on September 11, 2014
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International Journal of Surgical Pathology 22(5)
Figure 1. A relatively circumscribed tumor composed of spindle-shaped cells arranged in fascicles and storiform pattern.
Figure 2. Tumor cells have oval to elongated vesicular nuclei and pale eosinophilic cytoplasm with indistinct cell borders admixed with inflammatory cells.
2 well-defined, low-attenuation areas radiologically consistent with cysts (Hounsfield value 15). The rectal biopsies showed a moderately differentiated adenocarcinoma. Following discussion at the multidisciplinary team meeting, he underwent neo-adjuvant chemoradiotherapy. The follow-up computed tomography scan revealed an increase in the size of one of the splenic lesions from 15 mm to 22 mm. A decision to perform a low anterior resection with splenectomy was taken. Intraoperatively, the surgeon reported the spleen as macroscopically normal. At follow-up, the patient remains fit and well. There are 2 small left upper quadrant nodules thought to be hypertrophied splenunculi, and a nodule on the kidney that has remained the same size for 2 years. Figure 3. Tumor cells are positive with MNF 116 and AE1/3.
Histopathological Features The sections from the low anterior resection specimen showed a tubulovillous adenoma with high-grade dysplasia. There was complete regression of the invasive adenocarcinoma (pT2, N0, Mx) on the left rectal wall. The spleen measured 15 × 9.5 × 6 cm and weighed 358 g. The external surface showed multiple small nodular lesions, the largest of which measured 0.4 cm in maximum dimension. Cross sections revealed a grey white lesion toward the lower edge, which measured 0.9 × 0.8 × 0.6 cm. The adjacent parenchyma was largely unremarkable. Microscopic examination showed congested red pulp and some atrophy of white pulp of the spleen. The macroscopically identified lesion was a nodular, relatively circumscribed, but nonencapsulated lesion composed of spindle cells arranged in fascicles and focally in a storiform pattern (Figure 1). The cells had oval to elongated vesicular nuclei and pale eosinophilic cytoplasm with
indistinct cell borders (Figure 2). There were scattered admixed inflammatory cells, including large numbers of plasma cells. There was interstitial hemorrhage and in places pseudovascular spaces were also present. Mitoses were rare and there were no areas of necrosis. Immunohistochemistry showed the lesional cells to be strongly and diffusely positive for AE1/3 and MNF116 (Figure 3). They were also positive for SMA (Figure 4) and desmin. They were negative for S100, CD1a, CD21, and CD23, ruling out a dendritic cell tumor. They were also negative for CK7, CK20, and CDX2, thus ruling out metastatic carcinoma (Figure 4). The other immunostains for which the cells were negative included langerin, CD34, CD31, CD163, CD35, ALK-1, and EBER-ISH. The overall histological appearances and immunoprofile were concluded to be those of a fibroblastic reticulum cell tumor of spleen.
Downloaded from ijs.sagepub.com at UNIV OF WINNIPEG on September 11, 2014
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Karim et al
Figure 4. Tumor cells are positive with SMA and negative with CDX2, CK20, and CK7.
Discussion In 1980, Heusermann et al described the fibroblastic reticulum cell (FBRCs) from analysis of rabbit spleen. The cells are located within parafollicular areas of the deep cortex of lymph nodes, and in the extrafollicular areas of tonsils and the spleen, where they are an important component of the immunological stromal support network. Together with follicular dendritic cells (FDCs) and interdigitating dendritic cells (IDCs), they relate closely to the nodular reticular network to provide a structural complex and assist with the functional capacity of the immune system.1,2 In 1990, Doglioni et al documented the occurrence and distribution of cytokeratin immunoreactive reticulum cells in a series of normal and pathological human lymph nodes and spleens. These cells are apparently a normal subpopulation of reticulum cells, being detectable from the early stages of spleen and lymph node development. The awareness of these cells is of particular relevance in the search for micrometastatic foci using anti-cytokeratin antibodies.3 The individual subtypes of this group of support cells have a well-described tumor potential; however, documented clinical cases are much rarer. Nearly 10 years ago, Martel et al collated 3 pure FBRC tumors originating in
lymph nodes and described what is thought to be the first known FBRC tumor to originate from the spleen (which subsequently metastasized to the liver).1 It is a histologic and immunohistochemical challenge to distinguish these cells from their similar appearing counterparts. Nonetheless, greater diagnostic frequency has garnered a consistent repertoire of features to distinguish it as a diagnosable entity. FBRC tumors are characterized by spindle to oval cells with indistinct borders and copious cytoplasm staining weakly with eosin. They are often arranged in whorls, fascicles, sheets, or in a storiform pattern, features seen in our case.2,4,5 In concurrence with the morphological description in the literature, our case showed the presence of scattered inflammatory cells2,5 and a low rate of mitoses. There is often variable cytological atypia, and necrosis is rare. The presence of increased mitoses (>5/10 hpf), necrosis, and cellular atypia is known to be associated with poor prognosis.2,5 These features were not observed in our case. The immunoprofile of FBRCs is myofibroblastic in nature with positivity for vimentin, and often smooth muscle actin and desmin.1 In addition, a considerable, although variable, proportion of these FBRCs contain cytokeratins 8 and 18. Comparison of the distribution of cells expressing
Downloaded from ijs.sagepub.com at UNIV OF WINNIPEG on September 11, 2014
450
International Journal of Surgical Pathology 22(5)
cytokeratins and/or desmin with that of other reticulum cells suggests that the former represent a subset of the latter.6 No reports have confirmed the presence of EBV sequences. The most useful feature of their immunostaining characteristics is their negative reaction to CD21, CD23, CD35, and S100, which help distinguish FBRC tumors from others, particularly FDC tumors (CD21 and CD35 positive) and IDC tumors (S-100 positive) with which they share the same morphological appearances.1,2,4 Other tumors (in addition to FDCT and IDCT) to be considered during diagnosis would be inflammatory pseudotumor/inflammatory myofibroblastic tumor (IMT), angiosarcoma, fibrosarcoma, malignant fibrous histiocytoma, and palisaded myofibroblastoma; however, immunohistochemistry helps in narrowing down this list of diagnoses.1,2,5 IMT of spleen is composed of spindleshaped cells and an inflammatory cell component made up of plasma cells, lymphocytes, and histiocytes. In one of the larger series study of this tumor, Neuhauser et al found that most of their cases (11/12) were negative for cytokeratin marker and this could be used to distinguish between these tumors.7 FBRC tumors appear to be indolent and nonaggressive tumors although the presence of necrosis together with high mitotic rate and cytological atypia are indicators of a less favorable prognosis. Treatment is typically with surgical removal followed by some form of adjuvant oncological therapy.1,2,4 Interestingly given the limited number of reported cases, Chan et al also described cytokeratin-positive interstitial reticulum cells as a subset of fibroblastic reticulum cells identified mainly by their positivity with cytokeratins, CK8 and CK18.4 The tumor cells in our case showed positivity with cytokeratins AE1/AE3 and MNF116 together with the more accepted positive staining with smooth muscle actin and desmin. We would like to think that our case may belong to this even rarer group of tumors arising from a subset of fibroblastic reticulum cells in the spleen. In summary, diagnosed primary splenic FBRC tumors are extremely rare; however, our case presents the typical features used to diagnose this predominantly indolent tumor. Our patient remains well at follow-up after 2 years with no evidence of recurrence, or indeed bowel related disease.
Important Learning Points 1. This tumor has features shared with other primary splenic malignancies. Where knowledge of it as an entity is poor, it is and will remain an underdiagnosed condition, which may have implications for follow-up.
2. There are a few case reports of splenic fibroblastic reticulum cell tumor in the literature; hence, predicting its malignant potential remains a challenge. Comparisons with tumors of similar morphology may aid this process. 3. Fibroblastic reticulum cell tumors provide further evidence that normal stromal structures of the lymphoid system may not yet be fully defined. Acknowledgments The authors would like to acknowledge and express their gratitude to Dr S. Sankar Banerjee, Honorary Consultant Histopathologist at the Christie Hospital in Manchester, for his guidance and help with this case.
Declaration of Conflicting Interests The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding The author(s) received no financial support for the research, authorship, and/or publication of this article.
References 1. Martel M, Sarli D, Colecchia M, et al. Fibroblastic reticular cell tumour of spleen: report of a case and review of the entity. Hum Pathol. 2003;34:954-957. 2. Andriko Jo-Ann W, Kaldjian EP, Tsokos M, Abbondanzo SL, Jaffe ES. Reticulum cell neoplasms of lymph nodes: a clinicopathologic study of 11 cases with recognition of a new subtype derived from fibroblastic reticular cells. Am J Surg Pathol. 1998;22:1048-1058. 3. Doglioni C, Dell’Orto P, Zanetti G, Iuzzolino P, Coggi G, Viale G. Cytokeratin immunoreactive cells of human lymph nodes and spleen in normal and pathological conditions. An immunocytochemical study. Virchows Arch A Pathol Anat Histopathol. 1990;416:479-490. 4. Chan ACL, Serrano-Olmo J, Erlandson RA, Rosai J. Cytokeratin-positive malignant tumors with reticulum cell morphology: a subtype of fibroblastic reticulum cell neoplasm? Am J Surg Pathol. 2000;24:107-116. 5. Soilleux EJ. Recent advances in mastocytosis and neoplasms of probable monocytic/dendritic cell lineage. Diagn Histopathol. 2010;16:182-205. 6. Franke WW, Moll R. Cytoskeletal components of lymphoid organs. I. Synthesis of cytokeratins 8 and 18 and desmin in subpopulations of extrafollicular reticulum cells of human lymph nodes, tonsils and spleen. Differentiation. 1987;36:145-163. 7. Neuhauser TS, Derringer GA, Thompson LD, et al. Splenic inflammatory myofibroblastic tumor (inflammatory pseudotumor): a clinicopathologic and immunophenotypic study of 12 cases. Arch Pathol Lab Med. 2001;125:379-385.
Downloaded from ijs.sagepub.com at UNIV OF WINNIPEG on September 11, 2014
Fibroblastic Reticulum Cell Tumor of Spleen: A Case Report Zain Karim, Rajagopal Saravana, Patrick Shenjere and Fergus Reid INT J SURG PATHOL 2014 22: 447 originally published online 12 November 2013 DOI: 10.1177/1066896913509009 The online version of this article can be found at: http://ijs.sagepub.com/content/22/5/447
Published by: http://www.sagepublications.com
Additional services and information for International Journal of Surgical Pathology can be found at: Email Alerts: http://ijs.sagepub.com/cgi/alerts Subscriptions: http://ijs.sagepub.com/subscriptions Reprints: http://www.sagepub.com/journalsReprints.nav Permissions: http://www.sagepub.com/journalsPermissions.nav Citations: http://ijs.sagepub.com/content/22/5/447.refs.html
>> Version of Record - Jul 20, 2014 OnlineFirst Version of Record - Nov 12, 2013 What is This?
Downloaded from ijs.sagepub.com at UNIV OF WINNIPEG on September 11, 2014
509009
research-article2013
IJSXXX10.1177/1066896913509009International Journal of Surgical PathologyKarim et al
Case Report
Fibroblastic Reticulum Cell Tumor of Spleen: A Case Report
International Journal of Surgical Pathology 2014, Vol. 22(5) 447–450 © The Author(s) 2013 Reprints and permissions: sagepub.com/journalsPermissions.nav DOI: 10.1177/1066896913509009 ijs.sagepub.com
Zain Karim, MBBS1, Rajagopal Saravana, MBBS1, Patrick Shenjere, MBChB2, and Fergus Reid, MBChB1
Abstract Fibroblastic reticulum cells (FBRCs) belong to a major subtype of stromal support cells in the lymphoid system and rarely give rise to tumors. We report a case of fibroblastic reticulum cell tumor arising in the spleen. The tumor was clinically and radiologically mistaken for a metastatic deposit in the spleen. Microscopically the tumor was composed of spindle cells arranged in fascicles and storiform pattern. The cells had oval to elongated vesicular nuclei and pale eosinophilic cytoplasm with indistinct cell borders. There were admixed inflammatory cells, including large numbers of plasma cells. The tumor cells were positive for smooth muscle actin, desmin, AE1/AE3, and MNF116. They were negative for S100, CD1a, CD21, CD23, CD34, CD31, and CD35 among other markers. The morphological features and immunoprofile of this rare tumor in comparison to the few cases reported in the literature are discussed along with the positive reaction with cytokeratins and their relationship to the smaller subset of FBRCs, the cytokeratin-positive interstitial reticulum cells in the spleen. Keywords fibroblastic reticulum (reticular) cell, cytokeratin-positive interstitial reticulum cells, spleen
Introduction
Case Description
Fibroblastic reticulum cells of lymphoid tissue are regarded as a major subtype of dendritic cells that are the group of accessory cells providing structural and functional support to the immune system. The other subtypes of this group are the follicular dendritic cells and interdigitating dendritic cells. The latter 2 subtypes have been widely described in the literature with many studies characterizing the morphology and immunophenotype of these cells including tumors arising from them. There have been fewer reports of tumors arising from fibroblastic reticular cells. Their morphological features and immunophenotype have been less extensively studied as compared to the tumors arising from follicular dendritic cells (FDCT) and interdigitating dendritic cells (IDCT). We report a case of fibroblastic reticular cell tumor of the spleen that was mistaken for a metastatic deposit and discuss the morphological features and immunoprofile of these rare tumors with an aim to raise awareness of these tumors and also help in further clarifying the behavior of these tumors. We would also wish to draw attention to the smaller subset of fibroblastic reticular cells, the cytokeratin-positive interstitial reticulum cells, which are rare as a cause of tumors in the lymphoid system.
Clinical Features A 62-year-old Caucasian man presented to the Department of Surgery due to a family history of multiple familial gastrointestinal tract malignancies. He himself was completely symptom free, denying abdominal pain, rectal bleeding, changes in bowel habit, unexplained weight loss, or indeed any other features to suggest an underlying pathological process. Examination was unremarkable, and appropriate blood tests were all within normal limits. A colonoscopic examination showed 4 polyps in the descending colon and an area in the rectum suspicious for malignancy. Computed tomography and magnetic resonance imaging scans demonstrated a 20 × 27 mm low rectal tumor (T2, N0, Mx) and a bulky spleen (137 mm) with
1
Stepping Hill Hospital, Stockport, UK Christie Hospital, Manchester, UK
2
Corresponding Author: Zain Karim, Department of Surgery, Stepping Hill Hospital, Poplar Grove, Hazel Grove, Stockport SK2 7JE, UK. Email: [email protected]
Downloaded from ijs.sagepub.com at UNIV OF WINNIPEG on September 11, 2014
448
International Journal of Surgical Pathology 22(5)
Figure 1. A relatively circumscribed tumor composed of spindle-shaped cells arranged in fascicles and storiform pattern.
Figure 2. Tumor cells have oval to elongated vesicular nuclei and pale eosinophilic cytoplasm with indistinct cell borders admixed with inflammatory cells.
2 well-defined, low-attenuation areas radiologically consistent with cysts (Hounsfield value 15). The rectal biopsies showed a moderately differentiated adenocarcinoma. Following discussion at the multidisciplinary team meeting, he underwent neo-adjuvant chemoradiotherapy. The follow-up computed tomography scan revealed an increase in the size of one of the splenic lesions from 15 mm to 22 mm. A decision to perform a low anterior resection with splenectomy was taken. Intraoperatively, the surgeon reported the spleen as macroscopically normal. At follow-up, the patient remains fit and well. There are 2 small left upper quadrant nodules thought to be hypertrophied splenunculi, and a nodule on the kidney that has remained the same size for 2 years. Figure 3. Tumor cells are positive with MNF 116 and AE1/3.
Histopathological Features The sections from the low anterior resection specimen showed a tubulovillous adenoma with high-grade dysplasia. There was complete regression of the invasive adenocarcinoma (pT2, N0, Mx) on the left rectal wall. The spleen measured 15 × 9.5 × 6 cm and weighed 358 g. The external surface showed multiple small nodular lesions, the largest of which measured 0.4 cm in maximum dimension. Cross sections revealed a grey white lesion toward the lower edge, which measured 0.9 × 0.8 × 0.6 cm. The adjacent parenchyma was largely unremarkable. Microscopic examination showed congested red pulp and some atrophy of white pulp of the spleen. The macroscopically identified lesion was a nodular, relatively circumscribed, but nonencapsulated lesion composed of spindle cells arranged in fascicles and focally in a storiform pattern (Figure 1). The cells had oval to elongated vesicular nuclei and pale eosinophilic cytoplasm with
indistinct cell borders (Figure 2). There were scattered admixed inflammatory cells, including large numbers of plasma cells. There was interstitial hemorrhage and in places pseudovascular spaces were also present. Mitoses were rare and there were no areas of necrosis. Immunohistochemistry showed the lesional cells to be strongly and diffusely positive for AE1/3 and MNF116 (Figure 3). They were also positive for SMA (Figure 4) and desmin. They were negative for S100, CD1a, CD21, and CD23, ruling out a dendritic cell tumor. They were also negative for CK7, CK20, and CDX2, thus ruling out metastatic carcinoma (Figure 4). The other immunostains for which the cells were negative included langerin, CD34, CD31, CD163, CD35, ALK-1, and EBER-ISH. The overall histological appearances and immunoprofile were concluded to be those of a fibroblastic reticulum cell tumor of spleen.
Downloaded from ijs.sagepub.com at UNIV OF WINNIPEG on September 11, 2014
449
Karim et al
Figure 4. Tumor cells are positive with SMA and negative with CDX2, CK20, and CK7.
Discussion In 1980, Heusermann et al described the fibroblastic reticulum cell (FBRCs) from analysis of rabbit spleen. The cells are located within parafollicular areas of the deep cortex of lymph nodes, and in the extrafollicular areas of tonsils and the spleen, where they are an important component of the immunological stromal support network. Together with follicular dendritic cells (FDCs) and interdigitating dendritic cells (IDCs), they relate closely to the nodular reticular network to provide a structural complex and assist with the functional capacity of the immune system.1,2 In 1990, Doglioni et al documented the occurrence and distribution of cytokeratin immunoreactive reticulum cells in a series of normal and pathological human lymph nodes and spleens. These cells are apparently a normal subpopulation of reticulum cells, being detectable from the early stages of spleen and lymph node development. The awareness of these cells is of particular relevance in the search for micrometastatic foci using anti-cytokeratin antibodies.3 The individual subtypes of this group of support cells have a well-described tumor potential; however, documented clinical cases are much rarer. Nearly 10 years ago, Martel et al collated 3 pure FBRC tumors originating in
lymph nodes and described what is thought to be the first known FBRC tumor to originate from the spleen (which subsequently metastasized to the liver).1 It is a histologic and immunohistochemical challenge to distinguish these cells from their similar appearing counterparts. Nonetheless, greater diagnostic frequency has garnered a consistent repertoire of features to distinguish it as a diagnosable entity. FBRC tumors are characterized by spindle to oval cells with indistinct borders and copious cytoplasm staining weakly with eosin. They are often arranged in whorls, fascicles, sheets, or in a storiform pattern, features seen in our case.2,4,5 In concurrence with the morphological description in the literature, our case showed the presence of scattered inflammatory cells2,5 and a low rate of mitoses. There is often variable cytological atypia, and necrosis is rare. The presence of increased mitoses (>5/10 hpf), necrosis, and cellular atypia is known to be associated with poor prognosis.2,5 These features were not observed in our case. The immunoprofile of FBRCs is myofibroblastic in nature with positivity for vimentin, and often smooth muscle actin and desmin.1 In addition, a considerable, although variable, proportion of these FBRCs contain cytokeratins 8 and 18. Comparison of the distribution of cells expressing
Downloaded from ijs.sagepub.com at UNIV OF WINNIPEG on September 11, 2014
450
International Journal of Surgical Pathology 22(5)
cytokeratins and/or desmin with that of other reticulum cells suggests that the former represent a subset of the latter.6 No reports have confirmed the presence of EBV sequences. The most useful feature of their immunostaining characteristics is their negative reaction to CD21, CD23, CD35, and S100, which help distinguish FBRC tumors from others, particularly FDC tumors (CD21 and CD35 positive) and IDC tumors (S-100 positive) with which they share the same morphological appearances.1,2,4 Other tumors (in addition to FDCT and IDCT) to be considered during diagnosis would be inflammatory pseudotumor/inflammatory myofibroblastic tumor (IMT), angiosarcoma, fibrosarcoma, malignant fibrous histiocytoma, and palisaded myofibroblastoma; however, immunohistochemistry helps in narrowing down this list of diagnoses.1,2,5 IMT of spleen is composed of spindleshaped cells and an inflammatory cell component made up of plasma cells, lymphocytes, and histiocytes. In one of the larger series study of this tumor, Neuhauser et al found that most of their cases (11/12) were negative for cytokeratin marker and this could be used to distinguish between these tumors.7 FBRC tumors appear to be indolent and nonaggressive tumors although the presence of necrosis together with high mitotic rate and cytological atypia are indicators of a less favorable prognosis. Treatment is typically with surgical removal followed by some form of adjuvant oncological therapy.1,2,4 Interestingly given the limited number of reported cases, Chan et al also described cytokeratin-positive interstitial reticulum cells as a subset of fibroblastic reticulum cells identified mainly by their positivity with cytokeratins, CK8 and CK18.4 The tumor cells in our case showed positivity with cytokeratins AE1/AE3 and MNF116 together with the more accepted positive staining with smooth muscle actin and desmin. We would like to think that our case may belong to this even rarer group of tumors arising from a subset of fibroblastic reticulum cells in the spleen. In summary, diagnosed primary splenic FBRC tumors are extremely rare; however, our case presents the typical features used to diagnose this predominantly indolent tumor. Our patient remains well at follow-up after 2 years with no evidence of recurrence, or indeed bowel related disease.
Important Learning Points 1. This tumor has features shared with other primary splenic malignancies. Where knowledge of it as an entity is poor, it is and will remain an underdiagnosed condition, which may have implications for follow-up.
2. There are a few case reports of splenic fibroblastic reticulum cell tumor in the literature; hence, predicting its malignant potential remains a challenge. Comparisons with tumors of similar morphology may aid this process. 3. Fibroblastic reticulum cell tumors provide further evidence that normal stromal structures of the lymphoid system may not yet be fully defined. Acknowledgments The authors would like to acknowledge and express their gratitude to Dr S. Sankar Banerjee, Honorary Consultant Histopathologist at the Christie Hospital in Manchester, for his guidance and help with this case.
Declaration of Conflicting Interests The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding The author(s) received no financial support for the research, authorship, and/or publication of this article.
References 1. Martel M, Sarli D, Colecchia M, et al. Fibroblastic reticular cell tumour of spleen: report of a case and review of the entity. Hum Pathol. 2003;34:954-957. 2. Andriko Jo-Ann W, Kaldjian EP, Tsokos M, Abbondanzo SL, Jaffe ES. Reticulum cell neoplasms of lymph nodes: a clinicopathologic study of 11 cases with recognition of a new subtype derived from fibroblastic reticular cells. Am J Surg Pathol. 1998;22:1048-1058. 3. Doglioni C, Dell’Orto P, Zanetti G, Iuzzolino P, Coggi G, Viale G. Cytokeratin immunoreactive cells of human lymph nodes and spleen in normal and pathological conditions. An immunocytochemical study. Virchows Arch A Pathol Anat Histopathol. 1990;416:479-490. 4. Chan ACL, Serrano-Olmo J, Erlandson RA, Rosai J. Cytokeratin-positive malignant tumors with reticulum cell morphology: a subtype of fibroblastic reticulum cell neoplasm? Am J Surg Pathol. 2000;24:107-116. 5. Soilleux EJ. Recent advances in mastocytosis and neoplasms of probable monocytic/dendritic cell lineage. Diagn Histopathol. 2010;16:182-205. 6. Franke WW, Moll R. Cytoskeletal components of lymphoid organs. I. Synthesis of cytokeratins 8 and 18 and desmin in subpopulations of extrafollicular reticulum cells of human lymph nodes, tonsils and spleen. Differentiation. 1987;36:145-163. 7. Neuhauser TS, Derringer GA, Thompson LD, et al. Splenic inflammatory myofibroblastic tumor (inflammatory pseudotumor): a clinicopathologic and immunophenotypic study of 12 cases. Arch Pathol Lab Med. 2001;125:379-385.
Downloaded from ijs.sagepub.com at UNIV OF WINNIPEG on September 11, 2014
