Metastatic melanoma to the gallbladder presented as a polyp with acute cholecystitis: A case report from Syria.

Introduction and importance: Malignant melanoma is one of the most aggressive unpredictable tumors that can metastasize to any organ. Metastases from cutaneous melanoma to the gallbladder are exceedingly rare. Most patients with gallbladder metastases from malignant melanoma are usually asymptomatic; therefore, its diagnosis can be a real challenge. Case presentation: We report a case of a 71-year-old woman with a past history of cutaneous melanoma, who clinically presented with signs and symptoms of acute cholecystitis. Ultrasound investigation of the gallbladder revealed intraluminal polyp. Gross inspection of the excised gallbladder showed a polypoid lesion in the fundus. Microscopically, the H&E-stained sections revealed nests of malignant cells, occasionally with pigmented cytoplasm. The diagnosis of metastatic melanoma was reported, and supported by the results of the immunohistochemical stains. Clinical discussion: Malignant melanoma is a very aggressive type of skin cancer. It arises from the melanocytes in the epidermis, uvea, meninges, and intestinal tract. Worldwide, only 40 cases of metastatic melanoma to the gallbladder were documented. Moreover, reviewing the English-language literature showed that primary melanoma is an extraordinary event and was described in about 28 cases. Clinically, metastases from cutaneous melanoma to the gallbladder are usually asymptomatic. Conclusion: We report a metastatic malignant melanoma to the gallbladder presented as a polypoid lesion and clinically manifested as acute cholecystitis.