MULTIPLE LIPOMATOSIS: (FAMILIAL- SYMMETRIC)
Multiple Lipomatosis: Familial
This rare autosomal dominant condition is characterized by the development of multiple, encapsulated, subcutaneous, non-tender, smooth lipomas on the forearms, trunk, thighs, and arms. The lipomas are often symmetric, usually begin in early adulthood, and grow to a certain size and then stabilize; regression is rare, as is malignant degeneration. The distribution of the lipomas may follow that of the peripheral nerves (Leffell and Braverman 1986). In one family the condition was linked to an RBI gene mutation with low-penetrance retinoblastoma susceptibility (Genuardi et al. 2001).
Germline mutations in the HMGA2 gene may be responsible for dominant familial multiple lipomatosis, and that somatic mutations in this gene may be responsible for encephalocutaneous lipomatosis (Prontera et al. 2009).
Multiple Lipomatosis: Symmetric
This is a separate condition, predominantly occurring in adult males, and autosomal inheritance has been suggested. The primary defect is thought to be in adrenergic-stimulated lipolysis. Clinically, lipomatous masses develop in a symmetric distribution at the back of the neck and shoulders, the breast areas, abdomen, and pubic regions. There may be atrophy of uninvolved fat. Visceral lipomatosis can be life-threatening. Autonomic and peripheral neuropathy is associated, and alcoholism is thought to precipitate its development in many cases. The condition is probably heterogeneous and may not be genetic, but may be confused with multiple lipomatosis.
Autosomal dominant inheritance of multiple familial lipomatosis with polyneuropathy has been described (Wilson and Boland 1994; Stoll et al. 1996; Nisoli et al. 2002), and mutations in the mitochondrial genome, possibly resulting in faulty noradrenergic modulation of proliferation and differentiation of brown fat cells (Gamez et al. 1998; Nisoli et al. 2002; Enzi et al. 2002).