Refractory skin ulcers and afebrile bacteremia with Staphylococcus aureus in anti-melanoma differentiation-associated gene 5 antibody-positive dermatomyositis: a case report.

The skin ulcers sometimes appear in patients with anti-melanoma differentiation-associated gene 5 (MDA5) antibody-positive dermatomyositis (DM), and usually associates with disease activity. Here, we report a case of 41-year-old woman with anti-MDA5 antibody-positive DM, who developed refractory skin ulcers during the remission induction therapy, which were proven to be associated with clinically silent Staphylococcus aureus bacteremia with septic thrombi in her lung. The patient was referred to our hospital for the treatment of amyopathic DM with interstitial lung disease. Anti-MDA5-positive DM was diagnosed, and she was treated with triple therapy combined with tofacitinib because poor prognostic factors existed. Although the remission induction therapy improved most of symptoms, she developed erythematous rashes with ulcer on her left auricle and forearm, which were refractory to topical immunosuppressive medications. Despite the absence of systemic symptoms or elevated inflammatory markers, blood and wound cultures revealed S. aureus, and a new cavitary lesion was detected in her left lung. Subsequent antibiotic therapy resolved both the cutaneous and pulmonary lesions. This case highlights the importance of considering bacteremia and performing blood cultures when DM-related skin ulcers resist conventional treatments, even without fever during immunosuppressive therapy.