Primary Gastric Melanoma

Abstract

Melanoma represents 1-3% of all malignant cancers and typically appears in sites where melanocytes are commonly found, including the skin, eyes, meninges and anal region, most  commonly  in the rectum and sigmoid colon(1).

Most melanomas found in the stomach are metastases from cutaneous sources.

According to a clinicopathologic analysis of 652 patients with disseminated disease, 58% demonstrated small bowel metastases upon autopsy, 26% were found to have gastric metastases,but only 1.5% were identified to have any gastrointestinal lesions antemortem³⁴. Primary gastric melanoma is a rare entity with 11 cases reported worldwide(2).

Primary gastric melanoma is underdiagnosed, it’s symptoms and signs are nonspecific and specific staining techniques must be used to confirm the diagnosis. Therefore thorough physical examination, laboratory studies and imaging are required to rule out metastatic disease in the setting of metastatic melanoma

We have a case of a  man N.K 56 years old, with three fungoid lesions partially ulcerated, irregular shaped in corpus ventriculi, which histologically resulted to be a non epithelial and non lymphoid tumor of the stomach. It was performed also a laparoscopy with frozen biopsy for a lymphnode in the abdomen. The patient had also spleen metastatic lesion. A wide range of antibodies in immunohistochemistry were used in the differential diagnosis. A detailed clinical and radiologic  investigations revealed no primary lesion elsewhere.