Familial multiple lipomatosis

Familial multiple lipomatosis (FML) is a hereditary syndrome of multiple encapsulated lipomas which are found on the trunk and extremities, with relative sparing of the head and shoulders.

Terminology

It is clinically distinct from the similarly named multiple symmetric lipomatosis with which it is frequently confused in the dermatologic literature.

Epidemiology

FML is a rare benign hereditary syndrome and an incidence of 0.002% has been reported. Men are affected twice as commonly as women, and the condition generally manifests by the third decade of life.

Clinical presentation

The hallmark of FML are multiple, painless lipomas. These may cause discomfort, especially if large, but patients are generally not troubled by the disease.

Pathology

Lesions are multiple, rubbery, non-tender, mobile, and non-fluctuant, characteristic of multiple lipomas. They are located on the trunk and extremities, with relative sparing of the head and shoulders, and vary greatly in size. Although the lipomas usually range in size from a few millimeters to 6 cm in diameter, lipomas as large as 25 cm have been reported. Spontaneous regression and malignant degeneration are rare.

Genetics

FML is generally inherited by autosomal dominant transmission, although cases with recessive inheritance have also been reported.

Associations

The disease is not associated with any abnormalities in lipid metabolism.

Radiographic features

Although numerous, radiographic features are still indistinguishable from other lipomas on all imaging modalities (see lipoma for in-depth discussion of radiographic features).

Treatment and prognosis

The main treatment consists of surgical excision of the lesions responsible for cosmetic and functional impairment. Other possible treatment techniques include liposuction and injection lipolysis with phosphatidyl choline

Differential diagnosis

It is important to distinguish FML from other causes associated with subcutaneous lipomas such as Dercum disease, Madelung disease, Bannayan-Zonana syndrome and Cowden syndrome.