Lipomembranous changes in nodular-cystic fat necrosis

Three cases of nodular-cystic fat necrosis presenting with focal lipomembranous changes are reported. The lesions consisted of solitary (cases 1 and 3) or multiple (case 2) subcutaneous nodules on the upper (case 1) or lower (cases 2 and 3) extremities which had evolved over weeks to years. At surgical excision, solitary or multiple, freely mobile nodules within a cystic cavity were observed. Histologically, encapsulated fat nodules showing variable amounts of necrosis without marked inflammatory changes were present. Focal lipomembranous changes were observed in some nodules. Our observations seem to support the concept that lipomembranous changes are nonspecific and uncommon patterns of fat necrosis caused by a wide variety of local or systemic events that may cause a compromise in the blood supply of the subcutaneous tissue.