Histopathologic Spectrum of Connective Tissue Diseases Commonly Affecting the Skin.

Connective tissue disorders (CTDs), also known as collagen vascular diseases, are a heterogeneous group of diseases with a common pathogenic mechanism: autoimmunity. Precise classification of CTDs requires clinical, serologic, and pathologic correlation and may be difficult because of overlapping clinical and histologic features. The main contribution of histopathology in the diagnosis of these disorders is to confirm, rule out, or alert clinicians to the possibility of CTD as a disease category, rather than producing definitive diagnoses of specific entities. This article discusses the histopathologic spectrum of 3 common rheumatologic skin disorders: lupus erythematosus, dermatomyositis, and morphea (localized scleroderma).