A novel case report of balloon cell melanoma with metastasis to the ovary, brain, and lymph node

Summary: Balloon cell melanoma (BCM) is a rare histologic variant (<1%) of malignant melanoma characterized by large, foamy melanocytes with cytoplasmic vacuoles and pronounced nucleoli (“balloon cells”). Clinical presentation often varies and primary cutaneous lesions may be unknown in up to 47% of cases. Metastatic BCM tumors tend to display prominent balloon cell morphology, and cases have been reported involving organs of the gastrointestinal, urinary, ocular, and central nervous system tracts. However, ovarian involvement has not been well-reported. We present a novel biopsy-confirmed BCM case detected in a patient’s ovary with a primary cutaneous lesion previously found on the patient’s back in 2018. The ovarian lesion was initially thought to be a cyst, however the histology of the lesion was remarkable for metastatic balloon cells positive for melanocytic markers on immunostaining, including Melan-A, HMB45, SOX10, and tyrosinase. Brain and lymph node involvement was also detected, but unfortunately the patient was lost to follow-up due to wartime conflict and the remainder of the patient’s history is unknown. After conducting a thorough review of literature published on PubMed, the authors did not recognize previously reported cases of malignant BCM to the ovary to date. In this report, we recognize the importance of proper clinicohistologic and immunostain correlation when differentiating clear cell or xanthomatous lesions while briefly discussing how to differentiate these entities from BCM.