Multiple symmetric lipomatosis - a reflection of new concepts about obesity.

Multiple symmetric lipomatosis (MSL) is characterized by subcutaneous accumulation of nonencapsulated adipose tissue. In type 2 MSL accumulation occurs on proximal limbs, upper back and hips. This sometimes unrecognized disease is similar to an exaggerated female fat distribution and can be confused with simple obesity. Obesity is a heterogeneous disorder and we suppose that type 2 MSL might have a place on the edge of the obesity spectrum. Several contemporary concepts about adipose tissue could be recognized in the model of MSL. Changes in fat distribution among different depots of adipose tissue in obesity have emerged as origin of its metabolic complications. Decreased insulin resistance and raised adiponectin have been found in MSL just as in some other conditions with accumulation of the subcutaneous adipose tissue (SAT). In that context, MSL may present as a model for possible favourable metabolic impact of SAT depots. Adipogenesis in MSL is not a consequence of energy excess but it is an active hyperplastic proliferation of SAT. This kind of behaviour of some adipocytes in several subcutaneous areas in MSL suggests that the energy unrelated adipogenesis could contribute to the expansion of at least a part of SAT depot in obesity in general. Contrary to current concept that the signals for adipogenesis are dependent only on the energy equation, allowing this additional mechanism would imply a new approach to issues of obesity, foremost to differentiate its particular types for which these concepts may be relevant.