Anti-MDA-5 Dermatomyositis Presenting with Rapidly Progressive Interstitial Lung Disease: A Cautionary Tale

A 68-year-old Indian man presented with a pruritic eruption on his neck, back, elbows, knees, and the dorsum of his hands. He was initially treated for possible Lyme's disease by his primary care physician, but without improvement. Then he developed daily chills and fevers up to 101 °F, as well as shortness of breath. A chest radiograph showed patchy airspace opacities suggestive of atypical pneumonia, and the patient was treated with levofloxacin and prednisone. Although prednisone diminished the eruption, the patient continued to experience fever, malaise, and generalized weakness, at which point he was hospitalized. Blood cultures and an antinuclear antibodies (ANA) were negative and extensive lab workup was only notable for an elevated erythrocyte sedimentation rate (ESR) (63 mm/hr, Reference Range 0-22), mild transaminitis (AST 77 U/L, Reference Range 10-40), hyponatremia (131 mEq/L, Reference Range 135-145) and elevated ferritin (440, Reference Range 20-500). The patient was discharged on 20 mg of prednisone, with referral to rheumatology and dermatology for possible autoimmune diseases.