Isolated Gallbladder Intramucosal Metastatic Melanoma With Features Mimicking Lymphoepithelial Carcinoma.

Malignant melanoma has a variety of morphologic patterns and can metastasize and mimic any type of neoplastic process creating significant diagnostic difficulty. When metastasis to the gastrointestinal system is identified, it is most commonly associated with widely metastatic disease. We report a rare case of isolated gallbladder intramucosal metastatic melanoma with features mimicking lymphoepithelial carcinoma in an adult patient who presented with cholecystitis. Additionally, we report the imaging and morphologic features and discuss the importance of these findings along with a clear clinical history and immunohistochemical profile to make a definitive diagnosis.