Cutaneous lesions of dermatomyositis with supervening fibrosis

Dermatomyositis (DM) is a distinctive systemic connective tissue disease whereby the skin defines a cardinal site of involvement. There exists a body of literature, which suggests that a significant component of its clinical manifestations may be related to endothelial cell injury. We have postulated in the past that anti-endothelial cell antibodies may be the defining trigger leading to endothelial cell dysfunction. The primary organs affected by DM are the skin and muscle. A significant albeit rare complication is pulmonary fibrosis, which our recent study postulated to be attributable to an autoimmune endothelialitis.

We describe six patients, four women and two men who ranged in age from 3 to 60 years, and had classic clinical presentations and cutaneous lesions of DM without any supervening clinical changes indicative of cutaneous sclerosis.

Skin biopsies showed cell-poor interface dermatitis with variable dermal mucin and C5b-9 within the cutaneous vasculature. However, at variance with classic DM was the presence of a sclerodermoid tissue reaction, which was of variable depth. All of these patients had severe muscle involvement. One pediatric patient had concomitant significant cutaneous, central nervous system and oral mucosal ischemic infarcts. Significant pulmonary disease ensued in the four adult patients, manifesting as pulmonary fibrosis in two, diffuse alveolar damage in one and diaphragmatic failure in one. In three patients, direct immunofluorescent studies were corroborative of immune-based microvascular injury while Western blot and/or indirect immunofluorescent studies showed anti-endothelial cell antibody activity within the serum of three patients.

The identification of sclerosis in biopsies of skin lesions typical clinically for DM may be a harbinger for more severe autoimmune-based endothelial cell injury phenomenon. One could speculate that its basis may be attributable to elevated serum levels of the natural fibrogenic factor, transforming growth factor beta, which in turn is released from damaged endothelium.