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Journal of Clinical Oncology, Vol 23, No 4 (February 1), 2005: pp. 912-913 © 2005 American Society of Clinical Oncology. DOI: 10.1200/JCO.2005.03.094
Small Blue Cell Tumors of the RectumCASE 2. Small-Cell Carcinoma of the RectumDepartments of Anatomical Pathology, Colorectal Surgery, and Medical Oncology, Sydney Cancer Centre, Royal Prince Alfred Hospital, Sydney, Australia A 48-year-old white male presented with a 3-month history of gradually increasing bleeding per rectum. His medical background was unremarkable. He had been a smoker (40 cigarettes/day for 20 years). Initial colonoscopy revealed the presence of a 1-cm polyp approximately 10 cm from the anal verge. Pathology revealed a tubulovillous adenoma with mild dysplastic changes within the epithelium. However, within the lamina propria there was a high-grade neuroendocrine carcinoma of the small-cell type with lymphatic spread and extension to the margins of resection (Fig 1A). Staining was positive for CAM 5.2 and neuroendocrine markers including chromogranin, synaptophysin (Fig 1B), and neuron specific enolase. Staging computed tomography (CT) scanning revealed the presence of multiple liver metastases and a rectal tumor arising from the anterior wall of the rectum with extension into perirectal fat and seminal vesicles. No pulmonary pathology was detected. The hepatic metastases were also confirmed on positron emission tomography with fluorine-18-labeled fluorodeoxyglucose scanning (Fig 2). HIV antibodies were negative. He was initially treated with carboplatin and etoposide for four cycles that was stopped because of progression and toxicity (grade 3 to 4 fatigue). CT scanning confirmed a partial response in his liver metastases. Three months later, he was treated with cyclophosphamide, doxorubicin, and vincristine, which was tolerated for five cycles and accompanied by a complete response on CT scanning, with resolution of his liver metastases. He experienced disease relapse 5 months later with disease throughout his craniospinal axis; he was treated with an abbreviated course of craniospinal irradiation, which was ceased because of thrombocytopenia. He was referred to palliative care and died 17 months after the initial diagnosis.
Large bowel small-cell cancer is extremely rare, representing up to 0.2% of all large bowel malignancies.1,2 To date, approximately 100 cases have been reported in the English literature.3–6 Of those, the tumor is found in the rectum in approximately 40% of cases.7 The tumors are thought to be derived from a pluripotent neuroendocrine stem cell.8 Etiologic factors remain unknown. The pathologic features are similar to small-cell neuroendocrine carcinomas in other sites with closely packed cells with scanty cytoplasm, nuclear pleomorphism, high mitotic rate, and necrosis. Neuroendocrine differentiation can be demonstrated by immunochemical methods or electron microscopy. The differential diagnosis includes metastatic lung small cell carcinoma, which can only be excluded clinically; other small cell malignancies, which may occur in this region such as the more common basaloid or cloacogenic carcinoma, lymphoma, embryonal rhabdomyosarcoma, and amelanotic melanoma; and other neuroendocrine tumors such as carcinoid. Carcinoid can be distinguished from small cell carcinoma by its histologic pattern, low mitotic rate, and immunochemical staining features.9 The clinical behavior of the tumor in this patient resembled a pulmonary small cell tumor with rapid dissemination and initial sensitivity to chemotherapy. Long survival (10 to 20 years) has been reported after resection of a primary tumor,1 although median survival of 5 to 11 months3,10 is most commonly reported. Authors’ Disclosures of Potential Conflicts of Interest The authors indicated no potential conflicts of interest.
REFERENCES 1. Clery AP, Dockerty MB, Waugh JM: Small cell carcinoma of the colon and rectum: A clinicopathological study. Arch Surg 83:164-172, 1961 2. Robidoux A, Monte M, Heppel J, et al: Small-cell carcinoma of the rectum. Dis Colon Rectum 28:594-596, 1984 3. Gaffey MJ, Mills SE, Lack EE: Neuroendocrine carcinoma of the colon and rectum: A clinicopathologic, ultrastructural and immunohistochemical study of 24 cases. Am J Surg Pathol 14:1010-1023, 1990[Medline] 4. Wick MR, Weatherby RP, Weiland LH: Small cell neuroendocrine carcinoma of the colon and rectum: Clinical, histologic and ultrastructural study and immunohistochemical comparison with cloacogenic carcinoma. Hum Pathol 18:9-21, 1987[Medline] 5. Mills SE, Allen SM, Cohen AR: Small-cell undifferentiated carcinoma of the colon: A clinicopathological study of five cases and their association with colonic adenomas. Am J Surg Pathol 7:643-651, 1983[Medline] 6. Staren ED, Gould VE, Warren WH, et al: Neuroendocrine carcinomas of the colon and rectum: A clinicopathologic evaluation. Surgery 104:1080-1089, 1988[Medline] 7. Yaziji H, Broghammer WL Jr: Primary small cell undifferentiated carcinoma of the rectum associated with ulcerative colitis. South Med J 89:921-924, 1996[Medline] 8. Gladhill A, Hall PA, Cruse JP, et al: Enteroendocrine cell hyperplasia, carcinoid tumours and adenocarcinoma in long-standing ulcerative colitis. Histopathology 10:501-508, 1986[Medline] 9. Cebrian J, Larach S, Ferrara A, et al: Small-cell carcinoma of the rectum: Report of two cases. Dis Colon Rectum 42:274-277, 1999[Medline] 10. Saclarides TJ, Szeluga D, Staren ED: Neuroendocrine cancers of the colon and rectum, results of a ten-year experience. Dis Colon Rectum 37:635-642, 1994[Medline]
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Copyright © 2005 by the American Society of Clinical Oncology, Online ISSN: 1527-7755. Print ISSN: 0732-183X
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