Rare Presentation of Hibernoma as a Cystic Swelling

Hibernoma is a rare benign tumor of brown fat origin. It presents as a painless, slowly growing soft tissue tumor mimicking lipoma or liposarcoma, usually affecting adults, with a slight male predominance and a peak of incidence between the third and fourth decades of life. This is a case report of 35-year male, who presented with a mobile, fluctuant and transilluminant, swelling of 7 cm × 5 cm, on medial aspect of the right upper leg. Ultrasonography showed well-defined cystic lesion of varied echotexture with dense internal echoes and septation. Lesion was excised in-toto. On gross examination, it was a subcutaneous, multiseptate cyst containing clear serous fluid with cholesterol crystals with a solid area of 3 cm × 2 cm. Histopathological examination revealed large tumor cells with abundant granular (multivacuolated) cytoplasm. Postoperative recovery period was uneventful. We present this case as cystic degeneration in case of hibernoma.