954 Sarcoidosis Mimicking Progression of Melanoma: A Case Report

Abstract A 78-year-old lady with a history of malignant melanoma on the dorsal aspect her left foot, presented new fluorodeoxyglucose positron emission tomography (FDG-PET) avid lesion in fibular head. The patient had been diagnosed eight months previously 5.1mm Breslow thickness invasive melanoma. Following initial diagnosis, she underwent wide local excision and sentinel lymph node biopsy (SLN). was completely excised SLN negative for malignancy. Postoperatively, radiological staging computed scans (CT) thorax, abdomen, pelvis. This showed scattered pulmonary nodules, multiple indeterminate liver lesions. PET scan then performed, which an expansile, FDG-avid, lytic head, suspicious bone metastasis. discussion at multidisciplinary team meeting, open Histology revealed non-necrotising epitheloid granulomata without evidence Ziehl-Neelsen periodic acid Schiff stains were negative. findings suggestive sarcoidosis. previous diagnosis sarcoidosis 25 years prior, however, no known extrapulmonary disease not attending specialist. CT consistent Sarcoidosis is systemic inflammatory characterised by development non-caseating typically affect lungs nodes but can organ systems. case highlights diagnostic uncertainty FDG-avid PET, necessitating biopsy. uncommon possible differential this setting.