"Giant" subcutaneous composite classic/spindle cell lipoma

Lipomas belong to the most common soft tissue tumors. If they reach at least 10 cm or weigh at least 1,000 g, they are referred to as giant lipomas. Such lesions can cause diagnostic quandaries at a biopsy examination.

The article describes a 58-year-old man who observed the progression of a subcutaneous tumor mass in the right side of the back for two years. It looked like a fibrolipoma on an ultrasound. Complete surgical extirpation was performed. Grossly, it was an encapsulated lobulated lipomatous tumor measuring 12 × 10 × 4 cm. It consisted of a composite classical and spindle cell lipoma. The spindle cell component required differentiation from an atypical lipomatous tumor, which is an oncological entity with a worse prognosis.

Subcutaneous lipomas over 10 cm are rare and represent a diagnostic challenge for both clinicians and pathologists. We tried to point out that lipomatous tumors of larger dimensions and especially those with a heterogeneous morphological appearance should urge the pathologist to think about a potential malignancy and require more complex differential-diagnostic approach.