What are the clinical features of the different subtypes of morphea?
Several different classification systems exist for morphea. In general, these diseases can be categorized as: 1) circumscribed (plaque-variant), 2) generalized, 3) deep, and 4) linear (also known as linear scleroderma). Morphea is more common among Caucasians and females (3:1 compared with males). The etiology is unclear, but various infectious agents, trauma, and medications have been postulated. Borrelia infection has been linked to some cases of localized scleroderma in Europe but not in the United States. Skin involvement is common in the truncal region and can be seen in the breasts and extremities as well, but typically spares the hands and fingers. It is not associated with Raynaud’s phenomenon and does not typically affect internal organs, which separates it from SSc. Clinical features often differ by disease category:
• Circumscribed: most frequent subtype; comprises most cases of adults with morphea. Can present initially as a well-circumscribed lesion surrounded by an erythematous border. Later, the central portion may become indurated and sclerotic. The lesions can be shiny and may lack hair and exocrine glands similar to SSc. Interestingly, some lesions can present as pink or hyperpigmented macules and patches that do not become indurated (superficial morphea).
• Generalized: defined as four or more lesions (>3 cm in size) that involve two or more anatomic sites. Lesions are often symmetrical and may coalesce over time. Disabling pansclerotic morphea is a subtype of the generalized morphea category. This rare subtype occurs in childhood and can be rapidly progressive, involving deeper structures to the level of the bone and resulting in skin necrosis, open ulcers, muscle atrophy, and joint contracture. It is associated with an elevated risk of cutaneous squamous-cell carcinoma.
• Deep: rarest variant (accounts for 5% of localized scleroderma); involvement extends beyond epidermis and dermis, potentially including layers of fat, fascia, and muscle. Often symmetric; located on the extremities. More common in childhood.
• Linear (linear scleroderma): most common category among children. May affect a unilateral limb or less commonly the scalp and face ( en coup de sabre; most commonly in the region between the eyebrow and the hairline). Linear scleroderma can extend beyond the skin to fascia, muscle, and bone leading to tissue atrophy. Not associated with Raynaud’s phenomenon nor internal organ involvement, but some patients have arthritis (10%–15%). Neurologic symptoms and ocular disease (including uveitis) can occur in the en coup de sabre form and may overlap with the Parry–Romberg syndrome