Morphea

Morphea is a localized form of scleroderma confined to the skin and subcutaneous tissues, without the systemic manifestations characteristic of systemic sclerosis (systemic sclerosis primarily affects internal organs). The pathophysiology involves excessive collagen deposition in the dermis and subcutaneous tissues, mediated by transforming growth factor-beta (TGF-β) and other fibrogenic cytokines, with activation of fibroblasts and myofibroblasts. Morphea presents as circumscribed patches of induration with characteristic lilac ring (reddish-purple border) in early stages. Lesions typically begin as erythematous or violet patches that gradually harden and become sclerotic. Hypopigmentation or hyperpigmentation develops at lesion sites. Common locations include lower abdomen, flanks, upper back, and lower extremities. Morphea can be superficial (affecting dermis only) or involve subcutaneous tissue and muscle. Linear morphea (scleroderma en coup de sabre) can cause significant deformity, particularly when involving the face or affecting function over joints. En coup de sabre with facial involvement can cause hemifacial atrophy. Systemic symptoms and internal organ involvement (which define systemic sclerosis) do not occur with morphea.