Objectives: To demonstrate morphological changes in lipodermatosclerosis (LDS) and venous ulcers by histology, immunohistochemistry, electron microscopy and immunoelectron microscopy. Design: Single patient group study in patients with trophic skin changes in chronic venous insufficiency. Setting: Department of Dermatology, Medical University of Lübeck. Patients: Ten patients with venous leg ulcers. Interventions: Biopsies were taken from areas of LDS and compared with clinically normal-appearing skin of the affected leg and with ulcer tissue. Main outcome measures: Comparison of the morphological features on light and electron microscopy. Results: Superficial dermis. Histologically, the ulcer tissue and LDS skin show dilated tortuous vessels in a glomerulus-like arrangement in the superficial parts of the dermis. Ultrastructurally, the superficial vessels are surrounded by a cuff, which contains amorphous and basal membrane material and is most pronounced in LDS. Immunofluorescence studies reveal ill-defined perivascular staining after incubation with antibodies against fibrin(ogen), laminin and type IV collagen. The exact ultrastructural localization of type IV collagen within the perivascular cuff is observed by immunoelectron microscopy. Deep dermis. In deeper parts of the dermis, the vessels of both ulcer tissue and LDS are surrounded by cellular cuffs with pericytes, fibroblasts and compact collagen bundles. Conclusions: We suggest that the severe morphological changes in LDS and ulcer tissue play an important role in the pathogenesis of venous ulceration.
Lipocytes from normal rat liver release a neutral metalloproteinase that degrades basement membrane (type IV) collagen.