Anti-melanoma Differentiation-Associated Gene 5 (Anti-MDA5) Dermatomyositis: A Case Presentation.

We present a case of anti-melanoma differentiation-associated gene 5 (Anti-MDA5) dermatomyositis (DM) in a 30-year-old female. Anti-MDA5 dermatomyositis, previously termed clinically amyopathic dermatomyositis, was first recognized in 2005. Most cases present with varying combinations of cutaneous and oral ulcerations, palmar papules, respiratory symptoms, and minor muscle involvement (most commonly in the shoulders, upper arms, hips, thighs, and neck). This subtype of disease is most notable for its association with an increased risk of rapidly progressive interstitial lung disease. Our patient presented initially with only complaints of cutaneous ulcerations on the dorsal aspect of her hands. Following several months of no true diagnosis, she developed muscle weakness and joint pain. This led to retrieval of a punch biopsy which suggested anti-MDA5 DM at the top of the differential diagnoses. Immunoprecipitation revealed the presence of melanoma differentiation-associated gene 5 (MDA5) antibodies, confirming the diagnosis of anti-MDA5 dermatomyositis. This case demonstrates the importance of pinpointing the diagnosis of this rare disease subtype in a timely manner to prevent a fatal course, and we hope to inform dermatologists, rheumatologists, pulmonologists, and internists alike of the uncommon presentation of anti-MDA5 in an unsuspected, young patient.