A 62-year-old man presented as a new patient. He had no symptoms except a slowly growing left abdominal mass. It started developing approximately 8 years earlier, but he had not sought previous medical treatment. The patient did not have chest pain, shortness of breath, or bowel or bladder symptoms. His medical history was significant for hypertension and coronary artery disease. He had no history of abdominal surgery.

Physical examination revealed a large soft mass protruding from his left flank that was nontender, mobile, and subcutaneous (Figure 1). Urinalysis, complete metabolic profile, and complete blood count results were normal.

QUESTION

Based on the patient's history and physical examination, which one of the following is the most likely diagnosis?

• A. Angiolipoma.

• B. Epidermoid cyst.

• C. Lipoma.

• D. Liposarcoma.

• E. Rhabdomyosarcoma.

DISCUSSION

The answer is C: lipoma. The patient was counseled that he most likely had a noncancerous fatty tumor. Ultrasonography confirmed the presence of a solid subcutaneous mass. The patient noted that his brother had previously been treated for a similar mass. Surgery was performed, and a 17.5 × 13.5 × 11 cm mass weighing 1,259 g was removed. Histological examination demonstrated encapsulated benign adipose tissue with several focal areas of fat necrosis.