Gallbladder melanoma mimicking acute acalculous cholecystitis.

Gallbladder (GB) melanoma is a rare entity with a dismal prognosis. Its primary or secondary status is difficult to establish in the absence of an overt cutaneous localization. We report herein the case of a misdiagnosed GB melanoma mimicking acute acalculous cholecystitis that was treated by means of laparoscopic cholecystectomy (LC). A 54-year-old man was referred to our institution for acute cholecystitis. Apart from the ablation of some nevocytic nevi 7 years before admission, the patient's medical history was unremarkable. The ultrasound (US) examination showed a slightly enlarged acalculous gallbladder with thickened walls and a well-circumscribed polypoid mass in the fundus. The patient was treated medically and referred to LC. At surgery, some satellite nodules were visualized in the GB hepatic bed. The GB was removed, and two hepatic nodules were excised. Histology showed a pT3 melanoma. The patient underwent an open hepatic wedge resection 3 weeks after laparoscopy. No recurrence was observed at 6-month follow-up. To date, only one case of melanoma of the gallbladder treated with LC has been reported. GB melanoma is a diagnostic challenge when there is no evidence of a primary lesion. However, the occurrence of acalculous cholecystitis and a GB polyp in patients with a positive history of mole ablation should alert surgeons to the possibility of a melanoma.