Photosensitive Autoimmune Skin Diseases: Cutaneous Lupus and Dermatomyositis

Conclusions

• Ultraviolet radiation is a major trigger for both cutaneous lupus and dermatomyositis, and photoprotection is a foundational part of management.
• Cutaneous lupus and dermatomyositis can look similar histologically, but their clinical patterns, symptoms, and lesion distribution usually allow them to be distinguished.
• Photosensitivity is common in both diseases and is associated with worse quality of life and greater disease activity.
• Acute cutaneous lupus is typically linked to systemic lupus and presents with a transient malar-type facial eruption after sun exposure.
• Subacute cutaneous lupus tends to affect sun-exposed trunk and upper extremities and is often associated with anti-Ro/SSA antibodies.
• Chronic cutaneous lupus includes several subtypes, with discoid lupus being the most common and tending to scar and dyspigment.
• Lupus tumidus appears to be the most photosensitive cutaneous lupus subtype and often responds well to antimalarials.
• Dermatomyositis can present as a skin-predominant or amyopathic disease and has characteristic findings such as heliotrope rash, Gottron papules, and shawl sign.
• Compared with cutaneous lupus, dermatomyositis more often causes violaceous skin changes, muscle weakness, dysphagia, and possible interstitial lung disease.
• Serologic testing and targeted labs help separate the disorders, with lupus workup emphasizing ANA, dsDNA, and ENA antibodies, and dermatomyositis workup emphasizing myositis antibodies, CK, and aldolase.
• Treatment for cutaneous lupus generally escalates from topical therapy and antimalarials to immunosuppressants and biologics for refractory disease.
• Treatment for dermatomyositis often requires immunosuppressants such as mycophenolate or methotrexate, with IVIG or other agents used for more severe or refractory cases.