Anorectal melanoma – histopathological and immunohistochemical features and treatment

Prolapsed anorectal malignant melanoma presenting as hemorrhoids

Rectal bleeding in a patient with a history of hemorrhoids should not be ignored. It is often benign and resolves spontaneously without treatment. Here we present a case of anorectal malignant melanoma that presented with rectal bleeding and a prolapsed rectal mass.

A case report of anorectal malignant melanoma in the transitional zone

INTRODUCTION

Anorectal malignant melanoma is an uncommon and highly malignant disease with a greater incidence in females. Many patients were misdiagnosed as hemorrhoids, benign polyps, and rectal cancer. They were often diagnosed in an advanced stage. Wide local excision and abdominoperineal resection are the main treatments of rectal melanoma.

PRESENTATION OF CASE

A case report is a 77-year-old man who has blood in the stool for 4 months without clinical examination. He admitted to the emergency room with sudden syndromes that related to bowel perforation. Rectal examination detected a large anorectal polyp. Computer tomography showed free air and fluid in the peritoneal cavity. He was received laparoscopic surgery and found the fishbone penetrated the sigmoid colon without polyp resection. The polyp was treated by local excision a few days later. The histology examination was a primary malignant melanoma. Due to the pigmented lesion that remained from the resected polyp's root, the abdominoperineal resection was performed as a radical treatment.

DISCUSSION

Diagnosis of anorectal malignant melanoma is difficult because of atypical signs, that are confused with bleeding hemorrhoids especially an amelanotic melanoma. Treatment is controversial, including surgery, radiotherapy, chemotherapy, and target therapy. A present case is an option in radical surgery.

CONCLUSION

Anorectal melanoma is a rare disease with poor results and prognosis. A lack of large-data leads to a missing evidence-based guideline in this disease. Early-staging diagnosis and surgical treatment help patients improve their overall survival.

Spindle cell proliferations of the sigmoid colon, rectum and anus: a review with emphasis on perineurioma

A wide range of spindle cell proliferations are found uncommonly in the sigmoid colon, rectum and anus. They usually present as polyps, and include reactive lesions and benign and malignant neoplasms which may be primary or metastatic. They are less frequently described in the literature compared to those in the upper gastrointestinal tract, and may be underdiagnosed. The widespread use of sigmoidoscopy in symptomatic patients and bowel cancer screening programmes means that histopathologists must be aware of, and adopt a logical approach to, diagnosing spindle cell proliferations in biopsy and polypectomy specimens. This is particularly relevant given the strong association of some mesenchymal polyps with hereditary cancer syndromes. This review article will focus on perineurioma and the recent debate in relation to its overlap with fibroblastic polyp. The clinical, endoscopic, histological and immunohistochemical features of spindle cell proliferations which should be considered in the differential diagnosis of perineurioma will be discussed. There is also a brief reference to malignant spindle cell tumours of diagnostic importance.