Incidentally Detected Solitary Metastatic Melanoma of the Spleen Without Known Primary: A Case Report

Splenic masses could be secondary to infection or due to benign and malignant cancers. Due to its anatomy and microenvironment, the spleen is relatively protected from cancer spread. However, melanomas are one of the few cancers that metastasize to the spleen, but only 2% of these metastasize as solitary splenic masses. Among such a small fraction, only a handful have been reported without a known primary. Our patient, an elderly male in his early 60s, was diagnosed with metastatic melanoma of the spleen following a biopsy of the incidentally detected isolated splenic mass. Complete ocular, oral, and dermatological inspections were unremarkable for a probable primary. He responded well to immunotherapy and total splenectomy with no recurrence. Due to advanced imaging modalities in the modern era, the probability of isolated splenic masses as an initial presentation will increase, and a high index of clinical suspicion should be maintained for metastatic cancer as one of the differentials.