Hibernoma: 29-year-old male with a right thigh mass. Axial T1W (a), T2W (b), STIR (c) and T1W FS post-gadolinium (d) images show a hyperintense mass between the adductor longus and brevis muscles on the right. The signal intensity is similar to the adjacent fat on T1W and T2W; however, on STIR the mass is slightly hyperintense relative to the subcutaneous fat. Post-contrast images demonstrated heterogeneous enhancement. Axial (e) and coronal (f) fused FDG PET-CT demonstrate the marked FDG avidity of the mass. H&E (g), S100 (h), Desmin (i). Tissue obtained demonstrates multlivacuolated, polygonal cells with granular eosinophilic cytoplasm. Immunohistochemical stains are positive for S-100, and negative for desmin.