Cutaneous manifestations of connective tissue diseases are important to identify because they can be a clue to an undiagnosed systemic autoimmune disease. Many lesions, such as those seen in systemic lupus erythematosus (SLE) and dermatomyositis (DM), share a notable bright pink or purplish color, likely due to the intense lymphocytic inflammation found at the dermal-epidermal junction. Photosensitivity, as demonstrated best by the malar erythema of SLE and DM, is another shared feature of some connective tissue diseases, and therefore recognizing a photodistributed pattern is again important in this portion of the atlas.
Each subtype of lupus erythematosus has notable physical examination findings, including the scarring and dyspigmentation seen in discoid lupus erythematosus, the annular psoriasiform plaques of subacute cutaneous lupus erythematosus and neonatal lupus erythematosus, and the deeper palpable nodules or depressions of lupus profundus. Classically seen in DM as the heliotrope sign, some patients with DM or SLE will present with purplish patches of the eyelids.
This chapter also includes the spectrum of skin findings seen in localized and systemic scleroderma. Localized scleroderma (morphea) presents with an expanding, indurated, pink or lilac sometimes circinate, plaque that leaves scarlike dyspigmentation centrally and can lead to disfigurement, joint contractures, and skin ulcerations. In contrast, limited and systemic scleroderma present with distinctive cutaneous signs such as matlike telangiectasias, calcinosis cutis, and, in some, a symmetric, progressive, woody edema.
Patients with suspected connective tissue disease deserve a full review of systems and physical examination for rarer mucocutaneous findings, such as mucosal erosions or ulcerations, alopecia, sclerodactyly, nailfold capillary changes, and lymphadenopathy. Skin biopsies are almost always warranted and helpful when gathering information to confirm some of these difficult diagnoses.