A 38-year-old Latino man self-refers to dermatology for evaluation of a mass on his back that first appeared three years ago. Since then, it has grown steadily. There is no pain or discomfort associated with the lesion, and the patient claims to be quite healthy otherwise. There is no antecedent history for the affected area.
There is a subcutaneous, rubbery mass in the left infrascapular area. It measures 11 x 6 cm. Palpation reveals the lesion to be uniformly smooth and readily mobile. The overlying skin is free of abnormalities and increased warmth.
What is the diagnosis? DISCUSSION
Lipomas are by far the most common soft-tissue tumor to affect humans and are totally benign. They typically measure 2 to 3 cm in diameter, but as this case demonstrates, they can grow much larger. While the rate of growth in this case was unusual, the location—and other features—are typical.
Lipomas are actual tumors, composed completely of adipose tissue contained in a thin, fragile, membranous capsule. Their tendency to develop can be hereditary, though most are spontaneous. They can manifest internally as well.
Superficial lipomas, which often manifest as multiple lesions on the arms and trunk, are usually easy to remove surgically. Lesions that are deeper and older or that appear on the face, however, often require considerable dissection to be freed from surrounding tissue. When excision is attempted, it is essential to remove the entire lesion to prevent recurrence. And, as always, the specimen must be sent for pathologic examination.
Patients often decide against surgery once they understand the issues. This is acceptable, but any deviation from the norm—such as pain, irregular surface texture, change in overlying skin, lack of mobility, or rapid growth—would constitute reasonable grounds for excision.
This man’s lesion likely extended down to the muscle fascia if not into the muscle itself. As a result, surgery would require general anesthesia and placement of a drain in the inferior portion of the wound, since such a large defect would likely invite a collection of blood and serum. For these reasons, he was referred to a general surgeon.
The differential for lipoma includes liposarcoma and angiolipoma. The latter are common and benign but become painful and are often more firm than normal. Histologically, they’re often indistinguishable from ordinary lipomas. Liposarcomas, when superficial, can imitate ordinary lipomas, but their surfaces tend to be more irregular and firm and the lesions themselves less mobile.
TAKE-HOME LEARNING POINTS
- Lipomas are the most common soft-tissue tumor encountered in outpatient practices.
- While the vast majority are benign and easy to remove surgically, most lipomas can be safely left alone.
- When excision is attempted, the entire lesion must be removed lest it regrow.
- Patients with larger, deeper lesions, or those in busy anatomical areas, should be referred to a general surgeon.