Malignant rectal melanoma. Case report

Abstract

AIM: The aim of this study was to report a case concerning diagnostic and management of Anorectal melanoma.

MATERIAL: A 71 years old white man presented in our Institute with anal pain, tenesmus, blooding rectal during the last five months. The ano-rectal examination showed a brownish painful mass in the anal canal. The colonscopy and endoscopy showed a big stenotic mass from anal canal to medium rectum with a diameter of approximately 90 mm. 

RESULTS: Biopsy of the rectal mass was performed and the histopatological examination showed malignant ephitelioid cells, pigmented melanoma. The patient was treated by abdominoperineal resection with dissection of lymphnodes. Result of histopatological examination was ulcerated Malignant melanoma of the anal canal, growing polypoid with spindle cells and epithelioid infiltrating the mucosa, submucosa and the internal sphincter muscle. Vascular invasion. Subtotal lymph node metastasis in 3 of 17.

DISCUSSION: Anorectal melanoma is an uncommon and aggressive disease. The anorectum is the third most common location of malignant melanoma after the skin and retina. Lesions are difficult to diagnose because many are amelanotic  and patients present with nonspecific complaints such as anal discomfort or rectal bleeding.
After diagnosis, the main treatment available is surgical resection. Sentinel lymph node mapping has an unclear role in its management. Adjuvant therapy has long been recommended; however, there are no strong data to support its use.

CONCLUSIONS: There is no convincing evidence to indicate that abdominoperineal resection did not improve the survival rate of patients with malignant rectal melanoma as compared to the wide local excision, while the wide local excision had advantages in lower surgical risk and allowing patients to avoid permanent colostomy.