Malignant melanoma of the anal canal

Abstract

SYNOPSISThe clinical and pathological features of 15 cases of malignant melanoma of the anal canal are described.It would appear from this study that these tumours arise from squamous epithelium lining that part of the anal canal at or just above the line of the anal valves.Pack, Lenson, and Gerber (1952) MATERIAL AND METHODSA review of all benign and malignant tumours of the ano-rectal region in the records of this hospital is being pursued and has revealed the present total of 15 cases of malignant melanoma of the anal canal seen during this 22-year period. However, 10 of these have been seen in the last 12 years, which perhaps indicates a greater awareness of the diagnosis.In all but four of these patients an operation was carried out for removal of the primary tumour. The surgical specimens were prepared by cutting along the anterior aspect and stretching them out on a metal frame. The specimen was then photographed and the extent of local and lymphatic spread assessed by anatomical dissection and microscopy. Because of this routine method and the museum preservation of some specimens, it has been possible to make an accurate assessment of the exact site of origin of the primary tumour in the 11 cases treated by excision. In particular, the relationship of the tumour to the dentate line or line of the anal valves has been assessed as accurately as possible.All the histological sections were stained with haematoxylin and eosin and the presence of melanin was confirmed by Fontana's ammoniacal silver method.CLINICAL FEATURES AGE The ages of the 15 patients varied from 41 to 75 with an average age of approximately 59 years. This is much the same as the age incidence of adenocarcinoma of the rectum and squamous cell carcinoma of the rectum and squamous cell carcinoma of the anal canal (Morson, 1960b). SEX There were eight women and seven men. In squamous cell carcinoma of the anal canal there is a preponderance of women (Morson, 1960b), whereas adenocarcinoma of the rectum is commoner in men (Dukes and Bussey, 1958). However, Braastad et al. (1949) in their review of the literature report a 126 on 9 May 2018 by guest. Protected by copyright.

A Clinicopathological Correlation of Colorectal and Anal Canal Malignancy

“…Morsen and H. Volkstadt were found the average age of patient with malignant melanoma of 59 years with the age range 41 to 75 years and equal sex distribution. 10 There were only 2 cases of basaloid carcinoma in our study comprising of 0.93% of all microscopic types. Both were present in the anorectal region.…”

Primary anal malignant melanoma: a case report

“…12 It is presumed that primary anorectal malignant melanoma arises from normal melanocytes in the intestinal epithelium distal to the dentate line and extending proximally onto the rectum. 13 The staging of anal melanoma differs from that of cutaneous melanoma, which is based primarily on thickness in millimetres (Breslow classification). Anal melanoma is staged on a clinical basis, focusing on locoregional and distant spread.…”

Primary anorectal melanoma: a case of 5 year disease-free survival

“…Indeed, melanomatous lesions can affect the anal canal, the rectum, or both, with the majority occurring within 6 cm of the anal rim. 5,6 The exact causes of anorectal melanoma are not established yet. Sunlight exposure, particularly UVB radiation, is a well-known risk factor for cutaneous melanoma, but to date it is still unclear what triggers the development of mucosal melanoma, and specifically anorectal melanoma.…”

“…6 A timely diagnosis of anorectal melanoma is made even more difficult by the fact that up to 80% of lesions lack obvious pigmentation and up to 20% of tumors are even histologically amelanotic. 5,17 Therefore, patients presenting with bleeding and/or anorectal pain should undergo a thorough examination of the colon and rectum, and biopsies of any suspicious lesion should be obtained. Rarely, anal melanoma can be identified during routing pathologic examination of a hemorrhoidectomy specimen.…”