ABSTRACT
Objective To investigate the clinical and pathological features of anorectal malignant melanoma ( AMM) .Methods The clinical pathological and follow-up data of 7 cases of anorectal malignant melanoma were collected.The clinical and histopathological features and immunophenotype were analyzed .Results Among the 7 cases, 5 cases were female, 2 cases were male, aged 50-68 years, the average was 61 years.The tumors located in the lower rectum in 1 cases, 2 cases of teeth near the line , 4 cases of anal anus .The structure and morphology of the cancer cells were diverse .The organizational structures were mainly diffuse , focal and acinar .The cellular morphologies were mainly epithelioid , spindle and lymphocyte like .And the results of IHC showed the expression of the following three markers, vimentin, S-100 and HMB45, were strongly positive in cancer cells.However, the expression of CK , EMA and LCA were negative .And 2 cases of CEA expression were positive , LI Ki-67 was 20%-50%.Conclusions Anorectal malignant melanoma is one kind of rare malignant tumor and its characteristic morphology , immunophenotype could be helpful for diagnosis and differential diagnosis .