Vemurafenib-related sterile scrotal abscess in a patient with BRAFV600K-mutant advanced melanoma mimicking distant metastasis.

BACKGROUND Vemurafenib is a selective BRAF-inhibitor that has been approved for the use in patients with advanced BRAF-mutant melanoma. Major adverse events include skin rash, photosensitivity, pruritus, cutaneous squamous-cell carcinoma or keratoacanthoma. OBSERVATION We present the case of a patient experiencing extensive sterile abscess of the scrotum after nine months of treatment with vemurafenib for oligometastatic (liver) BRAF-mutant melanoma. The scrotal lesion mimicked distant metastasis in a first round of clinical and radiological examinations, but was identified as sterile abscess after surgical exploration and complete excision. The patient went on to receive hemihepatectomy for melanoma supposedly confined to the liver, and continues receiving vemurafenib. CONCLUSIONS We describe a remarkable case of probably vemurafenib-related sterile abscess. This adverse event is of substantial clinical relevance, as it mimicks metastatic melanoma and requires careful diagnostic evaluation and proper treatment to allow a favorable patient outcome.