•
•
Pedunculated Malignant Colonic Polyps with Superficial Invasion of the Stalks 1
Diagnostic Radiology
Theodore R. Smith, M.D. Malignant colonic polyps on substantial stalks were seen In 3 patients. In each case the base of the pedicle was free of tumor. The author suggests that these were initially benign adenomatous polyps but subsequently became malignant. These findings suggest that initially benign colonic polyps can become malignant over a period of time and that the presence of a substantial stalk may not always be pathognomonic of ~enignlty. INDEX TERM:
Colon, neoplasms
Radiology 115: 593-596, June 1975
Follow-up serial barium studies on July 21, 1970 and in August 1971 showed no reportable change. The patient continued to note blood in his stool every two or three weeks, but there was no history of weight loss. Sigmoidoscopy to a depth of 25 cm was negative, as was the physical examination. On April 10, 1972, a barium-enema and air-contrast examination revealed a polyp 2.3 cm in diameter on a relatively thick stalk approximately 3.5 cm long (Fig. 2, A). Colostomy and polypectomy were performed. The frozen section was thought to be benign, but the permanent section demonstrated "well differentiated adenocarcinoma" invading the stalk. The base of the stalk was free of tumor (Fig. 2, B). The patient has since been followed up by serial barium-enema studies and has been free of disease.
benign adenomatous polyps of the colon W degenerate to become carcinomas has been the HETHER
subject of considerable controversy since 1958, when Spratt et al. (18) concluded that the evidence did not support this theory. Castleman and Krickstein (4) agreed. On the other hand, many authors maintain that benign adenomatous polyps are often premalignant lesions (1,3,5, 11, 12, 16). The presence of a stalk measuring 2 cm or more, particularly one that is thin and pliable, has been cited as a reliable sign that a polypoid lesion is benign (13, 14). However, the following 3 cases appear to be exceptions to this rule; although the polyps had substantial stalks in each case, they were proved to be locally invasive malignant lesions pathologically. The bases of the stalks were free of tumor. These 3 cases were found in a retrospective review of both radiology and pathology departmental records of colonic polyps found and removed over an eight-year period at an active university hospital.
CASE III: A 62-year-old white man noted red rectal bleeding 12 years prior to admission, at which time a diagnosis of hemorrhoids was made. Proctoscopy was negative, and no further work-up was done. The bleeding stopped but returned periodically. A bariumenema study revealed a 3-cm polyp on a 2-cm stalk in the sigmoid colon (Fig. 3, A). Physical examination was noncontributory. At abdominal exploration, the polyp was found to be freely movable on a stalk as noted previously and did not involve the bowel wall. The pathologist reported adenocarcinoma limited to the mucosa and submucosa (Fig. 3, B).
CASE REPORTS CASE I: A 77-year-old white woman had noted a spot of blood on her pajamas two months prior to admission and on another occasion discovered blood in her stool. Physical examination was unremarkable. Sigmoidoscopy revealed a pedunculated polyp at a depth of 10 cm. A barium-enema examination with air contrast revealed a sigmoid polyp approximately 2.5 cm in diameter attached to a stalk measuring 3.5 cm. The surface of the potyp was somewhat corrugated (Fig. 1, A and B). The patient underwent a sigmoid polypectomy and had an uneventful recovery. The pathologist reported that "the superficial Y3 to Y2 of the polyp was replaced by well differentiated adenocarcinoma which infiltrated the stalk but did not involve the basal half of the adenomatous polyp." The colonic wall was free of tumor (Fig. 1, C). CASE II: A barium-enema examination of a 66-year-old white man obtained on July 14, 1970 disclosed a polyp with a long stalk.
DISCUSSION
Those who oppose the concept of a benign polyp becoming malignant point out that residual benign adenomatous tissue is almost never found in adenocarcinomas of the colon: Enterline et al. (6) found only 6 cases out of 666 frank carcinomas which they considered to have benign adenomatous tissue remnants, while Spratt at al. (18) stated that such remnants were virtually never seen in their review of 323 cases of colonic carcinoma. In those few cases in which residual benign tissue appears to be present, opponents of the transformation theory tend. to attribute this finding to well-differentiated adenocarcinoma. Others disaqree:
1 From the Department of Radiology (T. R. S., Assistant Professor), Albert Einstein College of Medicine, Bronx, N. Y. Revised version accepted for publication in December 1974. sjh
593
594
THEODORE
R. SMITH
June 1975
Fig. 1. CASE I. A. Lobulated 2.5-cm polyp on a freely movable stalk (arrow). B. Spot film shows the polyp on a long stalk. C. Malignant cells infiltrate the stalk (arrow) but do not involve the basal half of the stalk or the colon wall. (20X)
Fig. 2. CASE II. A. Close-up view of a 2.3-cm malignant polyp on a 3.5-cm-long stalk (arrow) in the descending colon. The stalk is thickest at its junction with the polypoid lesion. B. A well-differentiated adenocarcinoma involves the stalk (arrow); however, the base of the stalk is free of tumor, as is the bowel wall. (20X)
for example, Turell and Brodman found apparently benign adenomatous tissue in 16 of 150 cases of cancer of the colon and rectum and believed that the carcinoma had arisen from a previously benign adenoma (19). Long-term follow-up studies have been cited as
showing that virtually all adenomatous polyps remain benign (9). On the other hand, several authors have reported cancer developing at the site of supposedly preexisting benign adenomatous polyps (16, 17). There have also been several reports of well-documented co-
Vol. 115
595
PEDUNCULATED MALIGNANT COLONIC POLYPS
Diagnostic Radiology
Fig. 3. CASE III. A. 3-cm malignant, sightly lobulated polyp on a freely movable 2-cm stalk in the sigmoid colon. B. Malignant adenocarcinoma (arrow) which did not extend beyond the submucosa. Most of the stalk, including its base, was free of tumor. (SOX)
Ionic polyps with a focal malignant appearance and distant metastases but no local invasion (1, 10-12). The relative geographic distribution of benign adenomatous polyps and colonic carcinomas is also a matter of some debate. Those who accept the concept of malignant degeneration claim that colonic cancer and benign adenomatous polyps have a similar distribution pattern, with the preponderance of cases occurring in the rectum and rectosigmoid region (8). The de novo carcinoma advocates cite their own studies, which point to a much more uniform colonic distribution of benign polyps than the high incidence of rectal and distal sigmoid carcinoma would indicate (2). Authors also disagree as to whether patients with colonic cancer are more likely to exhibit benign adenomatous polyps than the general population (excluding familial polyposis) (3, 7). Radiographic assessment of the benign or malignant nature of a polyp seen on barium-enema and air-contrast examination depends on a number of factors. The size of polypoid lesions of the colon has been extensively correlated with malignancy (5, 13, 15, 20): the larger the diameter of the polyp, the greater the incidence of malignancy. The critical size of a polyp appears to be 10 mm, with the incidence of carcinoma becoming greater as the diameter of the lesion increases. Irregularity and lobulation of the surface of the lesion are also considered signs of malignancy (14). The contour of the adjacent bowel wall is probably even more significant: when the wall is tangent to the polyp or the base of the pedicle, thickening and/or irregularity of the wall is often indicative of malignancy. A substantial stalk or pedicle, particularly one which is mobile, has been considered a sign of benignity. Marshak studied a large series of pedunculated polyps and concluded that a long, thin stalk measuring 2 cm or more is a very good indication of benignity (14). The preceding 3 cases involved malignant polyps with substantial stalks measuring more than 2 ern; however, it
should be noted that in one case (CASE II) the pedicle was rather broad, though in CASES I and III the stalk was mobile and relatively slender. The micropathology of these colonic polyps is of interest. In all cases the carcinoma invaded the stalk superficially (Figs. 1, C, 2, C, and 3, B), but the tumor did not extend to the base of the stalk where it originated from the normal mucosa and submucosa. A colonic pedicle is generally thought to be the result of a nodule expanding and protruding into the lumen: at first a small tail of submucosal tissue forms an imperceptible pedicle, becoming gradually longer as the result of peristalsis and the pull created by passing intestinal contents. Manheimer reported an exceptional case in which a pedunculated malignant polyp metastasized to distant areas before the stalk became invaded by tumor ( 12). The fact that these carcinomas were on long stalks and did not extend to the bowel wall proper is significant. If they had in fact arisen de novo, it would have to be assumed that they grew very slowly and acquired long stalks over a considerable period of time. Yet in each case the stalk was only superficially invaded by tumor while the base was not involved, even though the polyps were of significant size. Those who believe that benign adenomatous polyps are capable of becoming malignant may consider it much more plausible that these were initially benign adenomatous polyps but subsequently became malignant. ACKNOWLEDGMENT: I wish to thank Dr. Boyce Bennett and Dr. Alfred Angrist of the Department of Pathology, Albert Einstein College of Medicine, for their valuable assistance.
REFERENCES 1. Bigelow B, Winkelman J: Polyps of the colon and rectum. A review of 12 years' experience and report of an unusual case. Cancer 17:1177-1186, Sep 1964 2. Blatt LJ: Polyps of the colon and rectum: incidence and distribution. Dis Colon Rectum 4:277-282, Jul-·Aug 1961
596
THEODORE R. SMITH
3. Buntain WL, ReMine WH, Farrow GM: Premalignancy of polyps of the colon. Surg Gynecol Obstet 134:499-508, Mar 1972 4. Castleman B, Krickstein HI: Do adenomatous polyps of the colon become malignant? N Engl J Med 267:469-475,6 Sep 1962 5. Culp CE: New studies of the colonic polyp and cancer. Surg Clin North Am 47:955-960, Aug 1967 6. Enterline HT, Evans GW, Mercado-Lugo R, et al: Malignant potential of adenomas of colon and rectum. JAMA 179:322-330, 3 Feb 1962 7. Grinnell RS, Lane N: Benign and malignant adenomatous polyps and papillary adenomas of the colon and rectum. An analysis of 1,856 tumors in 1,335 patients. Int Abst Surg 106:519-538, Jun 1958 8. Jackman RJ, Mayo CW: The adenoma-carcinoma sequence in cancer of the colon. Surg Gynecol Obstet 93:327-330, Sep 1951 9. Knoernschild HE: Growth rate and malignant potential of colonic polyps: early results. Surg Forum 14:137-138, 1963 10. Kraus FT:· Pedunculated adenomatous polyp with carcinoma in the tip and metastasis to lymph nodes. Dis Colon Rectum 8: 283-286, Jul-Aug 1965 11. Lane N, Kaye GI: Pedunculated adenomatous polyp of the colon with carcinoma, lymph node metastasis, and suture-line recurrence. Report of a case and discussion of terminology problems. Am J Clin PathoI48:170-182, Aug 1967 12. Manheimer LH: Metastasis to the liver from a colonic polyp. Report of a case. N Engl J Med 272:144-145,21 Jan 1965
June 1975
13. Margulis AR: The changing concepts of colonic polyposis. Editorial. Am J RoentgenoI113:386-388, Oct 1971 14. Marshak RH: The pedunculated adenomatous polyp. Am J Dig Dis 10:958-967, Nov 1965 15. Pagtalunan RJG, Dockerty MB, Jackman RJ, et al: The histopathology of diminutive polyps of the large intestine. Surg Gynecol Obstet 120:1259-1265, Jun 1965 16. Scarborough RA: The relationship between polyps and carcinoma of the colon and rectum. Dis Colon Rectum 3:336-342, Jul-Aug 1960 17. Smith TR, Maeir OM, Metcalf W, et al: Transformation of a pedunculated colonic polyp to adenocarcinoma? Report of a case. Dis Colon Rectum 13:382-386, Sep-Oct 1970 18. Spratt JS Jr, Ackerman LV, Moyer CA: Relationship of polyps of the colon to colonic cancer. Ann Surg 148:682-696, Oct 1958 19. Turell R, Brodman HR: Adenomas of the colon and rectum. [In] Turell R, ad: Diseases of the Colon and Anorectum. Philadelphia, Saunders, 1959, Vol 1, pp 312-374 20. Wychulis AR, Dockerty MB, Jackman RJ, et al: Histopathology of small polyps of the large intestine. Surg Gynecol Obstet 124:87-92, Jan 1967
Department of Radiology Albert Einstein College of Medicine Bronx, N. Y. 10461
•
Pedunculated Malignant Colonic Polyps with Superficial Invasion of the Stalks 1
Diagnostic Radiology
Theodore R. Smith, M.D. Malignant colonic polyps on substantial stalks were seen In 3 patients. In each case the base of the pedicle was free of tumor. The author suggests that these were initially benign adenomatous polyps but subsequently became malignant. These findings suggest that initially benign colonic polyps can become malignant over a period of time and that the presence of a substantial stalk may not always be pathognomonic of ~enignlty. INDEX TERM:
Colon, neoplasms
Radiology 115: 593-596, June 1975
Follow-up serial barium studies on July 21, 1970 and in August 1971 showed no reportable change. The patient continued to note blood in his stool every two or three weeks, but there was no history of weight loss. Sigmoidoscopy to a depth of 25 cm was negative, as was the physical examination. On April 10, 1972, a barium-enema and air-contrast examination revealed a polyp 2.3 cm in diameter on a relatively thick stalk approximately 3.5 cm long (Fig. 2, A). Colostomy and polypectomy were performed. The frozen section was thought to be benign, but the permanent section demonstrated "well differentiated adenocarcinoma" invading the stalk. The base of the stalk was free of tumor (Fig. 2, B). The patient has since been followed up by serial barium-enema studies and has been free of disease.
benign adenomatous polyps of the colon W degenerate to become carcinomas has been the HETHER
subject of considerable controversy since 1958, when Spratt et al. (18) concluded that the evidence did not support this theory. Castleman and Krickstein (4) agreed. On the other hand, many authors maintain that benign adenomatous polyps are often premalignant lesions (1,3,5, 11, 12, 16). The presence of a stalk measuring 2 cm or more, particularly one that is thin and pliable, has been cited as a reliable sign that a polypoid lesion is benign (13, 14). However, the following 3 cases appear to be exceptions to this rule; although the polyps had substantial stalks in each case, they were proved to be locally invasive malignant lesions pathologically. The bases of the stalks were free of tumor. These 3 cases were found in a retrospective review of both radiology and pathology departmental records of colonic polyps found and removed over an eight-year period at an active university hospital.
CASE III: A 62-year-old white man noted red rectal bleeding 12 years prior to admission, at which time a diagnosis of hemorrhoids was made. Proctoscopy was negative, and no further work-up was done. The bleeding stopped but returned periodically. A bariumenema study revealed a 3-cm polyp on a 2-cm stalk in the sigmoid colon (Fig. 3, A). Physical examination was noncontributory. At abdominal exploration, the polyp was found to be freely movable on a stalk as noted previously and did not involve the bowel wall. The pathologist reported adenocarcinoma limited to the mucosa and submucosa (Fig. 3, B).
CASE REPORTS CASE I: A 77-year-old white woman had noted a spot of blood on her pajamas two months prior to admission and on another occasion discovered blood in her stool. Physical examination was unremarkable. Sigmoidoscopy revealed a pedunculated polyp at a depth of 10 cm. A barium-enema examination with air contrast revealed a sigmoid polyp approximately 2.5 cm in diameter attached to a stalk measuring 3.5 cm. The surface of the potyp was somewhat corrugated (Fig. 1, A and B). The patient underwent a sigmoid polypectomy and had an uneventful recovery. The pathologist reported that "the superficial Y3 to Y2 of the polyp was replaced by well differentiated adenocarcinoma which infiltrated the stalk but did not involve the basal half of the adenomatous polyp." The colonic wall was free of tumor (Fig. 1, C). CASE II: A barium-enema examination of a 66-year-old white man obtained on July 14, 1970 disclosed a polyp with a long stalk.
DISCUSSION
Those who oppose the concept of a benign polyp becoming malignant point out that residual benign adenomatous tissue is almost never found in adenocarcinomas of the colon: Enterline et al. (6) found only 6 cases out of 666 frank carcinomas which they considered to have benign adenomatous tissue remnants, while Spratt at al. (18) stated that such remnants were virtually never seen in their review of 323 cases of colonic carcinoma. In those few cases in which residual benign tissue appears to be present, opponents of the transformation theory tend. to attribute this finding to well-differentiated adenocarcinoma. Others disaqree:
1 From the Department of Radiology (T. R. S., Assistant Professor), Albert Einstein College of Medicine, Bronx, N. Y. Revised version accepted for publication in December 1974. sjh
593
594
THEODORE
R. SMITH
June 1975
Fig. 1. CASE I. A. Lobulated 2.5-cm polyp on a freely movable stalk (arrow). B. Spot film shows the polyp on a long stalk. C. Malignant cells infiltrate the stalk (arrow) but do not involve the basal half of the stalk or the colon wall. (20X)
Fig. 2. CASE II. A. Close-up view of a 2.3-cm malignant polyp on a 3.5-cm-long stalk (arrow) in the descending colon. The stalk is thickest at its junction with the polypoid lesion. B. A well-differentiated adenocarcinoma involves the stalk (arrow); however, the base of the stalk is free of tumor, as is the bowel wall. (20X)
for example, Turell and Brodman found apparently benign adenomatous tissue in 16 of 150 cases of cancer of the colon and rectum and believed that the carcinoma had arisen from a previously benign adenoma (19). Long-term follow-up studies have been cited as
showing that virtually all adenomatous polyps remain benign (9). On the other hand, several authors have reported cancer developing at the site of supposedly preexisting benign adenomatous polyps (16, 17). There have also been several reports of well-documented co-
Vol. 115
595
PEDUNCULATED MALIGNANT COLONIC POLYPS
Diagnostic Radiology
Fig. 3. CASE III. A. 3-cm malignant, sightly lobulated polyp on a freely movable 2-cm stalk in the sigmoid colon. B. Malignant adenocarcinoma (arrow) which did not extend beyond the submucosa. Most of the stalk, including its base, was free of tumor. (SOX)
Ionic polyps with a focal malignant appearance and distant metastases but no local invasion (1, 10-12). The relative geographic distribution of benign adenomatous polyps and colonic carcinomas is also a matter of some debate. Those who accept the concept of malignant degeneration claim that colonic cancer and benign adenomatous polyps have a similar distribution pattern, with the preponderance of cases occurring in the rectum and rectosigmoid region (8). The de novo carcinoma advocates cite their own studies, which point to a much more uniform colonic distribution of benign polyps than the high incidence of rectal and distal sigmoid carcinoma would indicate (2). Authors also disagree as to whether patients with colonic cancer are more likely to exhibit benign adenomatous polyps than the general population (excluding familial polyposis) (3, 7). Radiographic assessment of the benign or malignant nature of a polyp seen on barium-enema and air-contrast examination depends on a number of factors. The size of polypoid lesions of the colon has been extensively correlated with malignancy (5, 13, 15, 20): the larger the diameter of the polyp, the greater the incidence of malignancy. The critical size of a polyp appears to be 10 mm, with the incidence of carcinoma becoming greater as the diameter of the lesion increases. Irregularity and lobulation of the surface of the lesion are also considered signs of malignancy (14). The contour of the adjacent bowel wall is probably even more significant: when the wall is tangent to the polyp or the base of the pedicle, thickening and/or irregularity of the wall is often indicative of malignancy. A substantial stalk or pedicle, particularly one which is mobile, has been considered a sign of benignity. Marshak studied a large series of pedunculated polyps and concluded that a long, thin stalk measuring 2 cm or more is a very good indication of benignity (14). The preceding 3 cases involved malignant polyps with substantial stalks measuring more than 2 ern; however, it
should be noted that in one case (CASE II) the pedicle was rather broad, though in CASES I and III the stalk was mobile and relatively slender. The micropathology of these colonic polyps is of interest. In all cases the carcinoma invaded the stalk superficially (Figs. 1, C, 2, C, and 3, B), but the tumor did not extend to the base of the stalk where it originated from the normal mucosa and submucosa. A colonic pedicle is generally thought to be the result of a nodule expanding and protruding into the lumen: at first a small tail of submucosal tissue forms an imperceptible pedicle, becoming gradually longer as the result of peristalsis and the pull created by passing intestinal contents. Manheimer reported an exceptional case in which a pedunculated malignant polyp metastasized to distant areas before the stalk became invaded by tumor ( 12). The fact that these carcinomas were on long stalks and did not extend to the bowel wall proper is significant. If they had in fact arisen de novo, it would have to be assumed that they grew very slowly and acquired long stalks over a considerable period of time. Yet in each case the stalk was only superficially invaded by tumor while the base was not involved, even though the polyps were of significant size. Those who believe that benign adenomatous polyps are capable of becoming malignant may consider it much more plausible that these were initially benign adenomatous polyps but subsequently became malignant. ACKNOWLEDGMENT: I wish to thank Dr. Boyce Bennett and Dr. Alfred Angrist of the Department of Pathology, Albert Einstein College of Medicine, for their valuable assistance.
REFERENCES 1. Bigelow B, Winkelman J: Polyps of the colon and rectum. A review of 12 years' experience and report of an unusual case. Cancer 17:1177-1186, Sep 1964 2. Blatt LJ: Polyps of the colon and rectum: incidence and distribution. Dis Colon Rectum 4:277-282, Jul-·Aug 1961
596
THEODORE R. SMITH
3. Buntain WL, ReMine WH, Farrow GM: Premalignancy of polyps of the colon. Surg Gynecol Obstet 134:499-508, Mar 1972 4. Castleman B, Krickstein HI: Do adenomatous polyps of the colon become malignant? N Engl J Med 267:469-475,6 Sep 1962 5. Culp CE: New studies of the colonic polyp and cancer. Surg Clin North Am 47:955-960, Aug 1967 6. Enterline HT, Evans GW, Mercado-Lugo R, et al: Malignant potential of adenomas of colon and rectum. JAMA 179:322-330, 3 Feb 1962 7. Grinnell RS, Lane N: Benign and malignant adenomatous polyps and papillary adenomas of the colon and rectum. An analysis of 1,856 tumors in 1,335 patients. Int Abst Surg 106:519-538, Jun 1958 8. Jackman RJ, Mayo CW: The adenoma-carcinoma sequence in cancer of the colon. Surg Gynecol Obstet 93:327-330, Sep 1951 9. Knoernschild HE: Growth rate and malignant potential of colonic polyps: early results. Surg Forum 14:137-138, 1963 10. Kraus FT:· Pedunculated adenomatous polyp with carcinoma in the tip and metastasis to lymph nodes. Dis Colon Rectum 8: 283-286, Jul-Aug 1965 11. Lane N, Kaye GI: Pedunculated adenomatous polyp of the colon with carcinoma, lymph node metastasis, and suture-line recurrence. Report of a case and discussion of terminology problems. Am J Clin PathoI48:170-182, Aug 1967 12. Manheimer LH: Metastasis to the liver from a colonic polyp. Report of a case. N Engl J Med 272:144-145,21 Jan 1965
June 1975
13. Margulis AR: The changing concepts of colonic polyposis. Editorial. Am J RoentgenoI113:386-388, Oct 1971 14. Marshak RH: The pedunculated adenomatous polyp. Am J Dig Dis 10:958-967, Nov 1965 15. Pagtalunan RJG, Dockerty MB, Jackman RJ, et al: The histopathology of diminutive polyps of the large intestine. Surg Gynecol Obstet 120:1259-1265, Jun 1965 16. Scarborough RA: The relationship between polyps and carcinoma of the colon and rectum. Dis Colon Rectum 3:336-342, Jul-Aug 1960 17. Smith TR, Maeir OM, Metcalf W, et al: Transformation of a pedunculated colonic polyp to adenocarcinoma? Report of a case. Dis Colon Rectum 13:382-386, Sep-Oct 1970 18. Spratt JS Jr, Ackerman LV, Moyer CA: Relationship of polyps of the colon to colonic cancer. Ann Surg 148:682-696, Oct 1958 19. Turell R, Brodman HR: Adenomas of the colon and rectum. [In] Turell R, ad: Diseases of the Colon and Anorectum. Philadelphia, Saunders, 1959, Vol 1, pp 312-374 20. Wychulis AR, Dockerty MB, Jackman RJ, et al: Histopathology of small polyps of the large intestine. Surg Gynecol Obstet 124:87-92, Jan 1967
Department of Radiology Albert Einstein College of Medicine Bronx, N. Y. 10461
