Primary malignant melanoma of the gallbladder with multiple metastases: A case report

RATIONAL: Primary malignant melanoma of the gallbladder is an extremely rare tumor, with fewer than 40 cases reported in the literature worldwide. The majority of patients presented as a solitary lesion in the gallbladder. To our knowledge, only one case of primary malignant melanoma of the gallbladder with multiple metastases has been reported, which involved the stomach, duodenum, pancreas, jejunum and a mesenteric lymph node. PATIENT CONCERNS: We report a case of primary malignant melanoma of the gallbladder with metastases to the duodenal bulb, right adrenal and a celiac lymph node. DIAGNOSES: Primary malignant melanoma of the gallbladder with multiple metastases. INTERVENTIONS: Gastrojejunostomy, cholecystectomy, and biopsy of the three metastatic lesions were performed. Histopathologic examination revealed melanin pigments were within the tumor cells of the four lesions, however, junctional activity was noted only in the gallbladder, supporting that the gallbladder was the primary site. No pigmented lesions were detected on the skin or eyes. The postoperative recovery was uneventful, and subsequently, chemotherapy with paclitaxel and carboplatin was administered. OUTCOMES: The patient survived for 16 months due to tumor. progression. LESSONS: The current case was unique due to the adrenal involvement. For patients with multiple metastases of malignant melanoma, gallbladder origin should be considered in the differential diagnosis from cutaneous origin.