Histopathological Studies in Lipodermatosclerosis Associated with Venous Hypertension. Pathophysiological

Summary Lipodermatosclerosis (LDS) or sclerosing panniculitis is an induration of the dermis, hypodermis and sometimes the superficial fascia. It is a chronic inflammatory process usually related to venous pathology, with neo-vascularization, adipose tissue necrosis and fibrosis. Several hypotheses have been proposed, but the exact mechanism is still unknown. In this paper we studied the skin biopsies of 6 patients with chronic LDS. We performed histochemical techniques, immunolabelling of methalloproteinases 1, 2 and 3; CD68, alpha smooth muscle actin and plastic semithin sections. Our main findings were: venous vessels were altered, with narrow lumens intimal fibrosis and hyperplasia, some arterial vessels also showed fragmentation and reduplication of internal elastic layer with subintimal fibrosis. There was a remarkable disorganization of reticular and hypodermal layer due to a intense fibrosis. Typical area of pseudomembranous fatty necrosis and pseudocyst were observed. There were patchy mixed inflammatory infiltrates in all skin layers involved. Methalloproteinases 1, 2 and 3 were positive in epidermis, endothelial cells, in some dermal and hypodermal cells, outlining pseudocysts and in pseudomembranous fat necrosis. In plastic semithin sections the presence of lipids droplets permeating between collagen fibers even in superficial dermis were evident.