Nontraumatic giant fat necrosis of the breast presenting as a rapidly growing tumor.

Nontraumatic rapid growing giant fat necrosis of the breast mimicking breast tumors is a rare clinical manifestation. The imaging features of the fat necrosis which range from benign to malign findings may be better explained with associated aetiology. The present paper reports a 54-year old woman with a rapid growing, fibrous, and hard giant mass originating in the subareolar region of the left breast. Mammography and magnetic resonance imaging demonstrated a heterogeneous, well circumscribed mass in 12 × 12 cm size in the left breast. The lesion was suspected as a malignant tumor and underwent core biopsy. The histopathology examination of the biopsy revealed mononuclear cells, foamy, vacuolated, and bubbly cells containing fat. Excision biopsy of the mass was performed and the final pathological diagnosis was confirmed as fat necrosis. The wide clinical and radiologic manifestations of fat necrosis are still difficult to diagnose even with the new diagnostic modalities and a great proportion of these lesions need a biopsy to diagnose.