A Case of Muscle Sarcoidosis Who Developed a Subcutaneous Nodule on His Right Cheek: The Diagnostic Application of Positron Emission Tomography (PET)

Abstract

A 50-year-old man noticed an asymptomatic, small, subcutaneous nodule on his right cheek four months before his first visit. The findings of magnetic resonance imaging of his head were not able to role out a malignancy. However, a positron emission tomography (PET) image showed 2-[fluorine-18]-fluoro-2-deoxy-D-glucose (FDG) accumulation in his cheek. Furthermore, multiple FDG accumulations were detected in the soft tissues of his extremities. The distribution of FDG uptake suggested the inflammatory changes of sarcoidosis. Histopathologically, his right cheek nodule consisted of non-caseating epithelioid cell granulomas. There was no indication of sarcoidosis in his other organs. We tried taking random skeletal muscle biopsies to confirm the diagnosis. We diagnosed him with muscle sarcoidosis, because epithelioid granuloma was detected in his right gastrocnemius muscle. PET imaging is a potent tool for detecting early guranulomatous inflammatory changes and may help in diagnosing sarcoidosis.