Unusual Clinical Presentation of Clear Cell Sarcoma in a Young Woman.

Clear cell sarcoma (CCS) is a rare but aggressive malignancy that typically occurs in young adults and is characterized by soft tissue tumors of the extremities. CCS can be difficult to distinguish from metastatic melanoma based solely on histology and immunohistochemistry (IHC) because of the significant overlap between them. However, it is imperative to get an accurate clinical diagnosis, as it informs disease staging and treatment options for patient care. Present in approximately 75% of CCS cases, the EWSR1 gene rearrangement detected by fluorescence in situ hybridization (FISH) can help with establishing a diagnosis; the underlying reciprocal translocation has never been reported in cutaneous melanoma. We reviewed a case of a young woman who presented with a confusing picture of widespread lymphadenopathy, cutaneous metastases, and electrolyte derangements and was subsequently diagnosed with metastatic CCS.This case suggests possible value in performing molecular testing when a clinical picture does not correspond with what is expected for melanoma. It also raises the question of whether CCS cases may be underreported. This case highlights an uncommon presentation that may not be recognized as a manifestation of CCS by an oncologist who is not a sarcoma specialist. It is unclear how COVID-19 vaccination contributed to her clinical presentation, and it is also unclear whether an early diagnosis would have changed her clinical outcome.