Lipomi

Lipomi are benign tumors composed of mature adipose tissue. In Italian medical terminology, lipomi is the plural form of lipoma; in English usage, lipoma is the preferred term. Lipomi are the most common benign soft tissue tumors in adults and can occur at any site where fat tissue is present, most often in the subcutaneous layer of the trunk and limbs.

They typically present as soft, painless, well-circumscribed, mobile nodules. Growth is usually slow over years. Most measure 1 to 5 cm, though larger lesions can occur. Most lipomi are solitary, but multiple lipomas can be seen in conditions such as familial multiple lipomatosis or adiposis dolorosa variants. Subtypes include intramuscular lipoma, fibrolipoma, spindle cell lipoma, and angiolipoma.

Diagnosis is usually clinical. Imaging is used when the diagnosis is uncertain or when deeper lesions are suspected. Ultrasound is often the initial study and shows a well-defined, homogeneous mass with echogenicity similar to adipose tissue. MRI or CT demonstrates fat-density and characteristic signal on T1- and T2-weighted sequences, with signal suppression on fat-saturated sequences. A biopsy may be required if imaging features are atypical or to exclude liposarcoma.

Management ranges from observation to surgical excision. Asymptomatic lipomi that do not concern cosmesis may be left alone. Excision is curative for most lesions and is indicated for symptomatic, enlarging, or cosmetically problematic masses. Recurrence is uncommon, but infiltrative lipomas and deep-seated lesions have a higher risk of regrowth.

Prognosis is excellent, and malignant transformation of lipomas is exceedingly rare.