Familial multiple lipomatosis

Familial multiple lipomatosis (FML), also known as hereditary multiple lipomatosis, is a rare genetic condition characterized by the development of numerous benign fatty tumors (lipomas) distributed symmetrically across the body. These lipomas are soft, painless, encapsulated subcutaneous masses composed of mature adipose (fat) tissue. They most commonly appear on the trunk, extremities (particularly the forearms and thighs), and occasionally on the neck and shoulders. The condition primarily affects the integumentary system and subcutaneous tissue, though the lipomas generally do not involve deeper structures such as muscles or internal organs. Familial multiple lipomatosis typically manifests in adulthood, often between the third and fifth decades of life. The lipomas tend to increase in number and size over time. While the condition is generally considered benign and the lipomas rarely undergo malignant transformation, they can cause cosmetic concerns and occasionally local discomfort or pain due to compression of nearby nerves. Unlike Dercum disease (adiposis dolorosa), the lipomas in FML are usually painless, and unlike multiple symmetric lipomatosis (Madelung disease), FML lipomas are well-encapsulated and more widely distributed rather than forming diffuse, unencapsulated fatty masses around the neck and shoulders. There is no curative treatment for familial multiple lipomatosis. Management is primarily symptomatic and includes surgical excision or liposuction of individual lipomas that cause pain, functional impairment, or significant cosmetic distress. However, recurrence after removal is possible, and new lipomas may continue to develop. Genetic counseling is recommended for affected families. The exact genetic basis remains incompletely characterized, though some studies have suggested linkage to chromosome 12q13-q15, a region containing the HMGA2 gene involved in adipocyte biology.

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