Primary gastric melanoma with pancreatic metastasis: a case report

We report an extremely rare case of primary gastric melanoma with pancreatic metastasis. As far as we know, the concept of primary gastrointestinal melanoma is currently controversial, because there are very few reports of primary gastrointestinal melanoma. At the same time, isolated pancreatic metastases are also very rare. The patient was admitted to the hospital with a main complaint of decreased appetite, and then underwent gastroscopy and found a mass in the stomach. The mass was initially diagnosed as poorly differentiated adenocarcinoma following a gastroscopic biopsy. The patient underwent radical total gastrectomy, pancreatic body and tail resection, splenectomy, and Roux-en-Y esophagojejunostomy. After further immunohistochemical examination of the surgically removed tissue, malignant melanoma was diagnosed. The tumor cells were arranged in sheets or nests with infiltrating growth, the cell sizes were inconsistent, nucleoli were obvious, and melanin particles were seen in the cytoplasm of some cells. The tumor cells were positive for MITF and S-100. Detailed systemic and imaging examinations did not find any other primary lesions. The patient denied any melanoma and skin lesion history. We believe this is a manifestation of primary gastric melanoma. We report this rare case of gastric melanoma with the aim of increasing clinicians' awareness of non-cutaneous melanoma and its treatment methods.

Primary gastric melanoma of unknown origin: a case report and short literature review

Though being usually a cutaneous tumor, melanomas can occur in several extracutaneous sites. Primary mucosal melanomas are rare, and primary gastric mucosal melanomas are considered extremely rare. Compared with cutaneous and ocular melanoma, mucosal melanomas have the lowest five-year survival. High level of suspicion of such rare condition may be the only way for early detection, diagnosis and chance for successful management of similar cases. In the present report, a case of a primary gastric melanoma in a 73-year-old man is described, along with a short review of the literature.

[Gastrointestinal locations of primary melanoma]

Primary gastrointestinal melanomas, part of the mucosal melanoma group, are uncommon. They constitute about five percent of all melanomas and most of them are located in the rectum (3 percent of all melanomas). The prognosis is poor, overall 5-year survival in rectal melanoma is 10-20 percent. We present three of our cases. The first case - a 68-year-old male patient - was operated on for histologically proved rectal melanoma. Three years after radical excision and oncological treatment a metastasis of the primary tumor was diagnosed in the stomach. Total gastrectomy was performed, followed by oncological treatment. In the second case of a 59-year-old male patient an appendectomy was performed for symptoms of appendicitis. The histopathological examination revealed melanoma of the appendix. Further investigations revealed the primary tumor in the stomach and metastases in the lungs as well. The third case - an 82-year-old female patient - was investigated for frequent defecations, mucus in stool and fecal incontinence. Primary melanoma was proved in the lower third of the rectum with multiple hepatic metastases. These three cases in our practice are remarkable for the rarity of the disease, and in two cases the presence of both the primary tumor and the metastasis were located in the gastrointestinal tract.