Metastatic melanoma presenting as rapidly enlarging hepatic cysts

Malignant melanoma is a highly aggressive disease with a propensity for metastatic spread. Although recent advances in targeted therapies have improved outcomes, effective screening for metastasis remains an important area of further research. We present a case of a man in his 70s who was recently diagnosed with recurrent, locally advanced melanoma. He presented with abdominal fullness, jaundice, and poor appetite. MR imaging of the abdomen revealed innumerable hepatic cysts with internal fluid-fluid levels which were markedly increased in size and number from recent imaging. These findings necessitated a broad differential that included parasitic or bacterial infection, metastases, or drug-induced polycystic liver disease. Subsequent biopsy revealed metastatic melanoma consistent with the patient's primary tumor. The patient was ultimately transitioned to comfort care measures due to the burden of the liver metastases and passed away shortly after presentation.