Korean J Dermatol.  2024 May;62(4):242-246.

Cutaneous Nontuberculous Mycobacterial Infection Misdiagnosed as Rheumatoid Nodule in a Patient with Rheumatoid Arthritis

• Ha NG
• Ha DL
• Kim JY
• Jang YH
• Lee WJ
• Lee SJ
• Park KD

Abstract

Owing to advances in diagnostics and the increase in invasive procedures, and immunocompromised patients, cutaneous nontuberculous mycobacteria (NTM) infection is rising. NTM should be suspected in patients with persistent skin lesions refractory to treatment with a history of immunosuppression or skin injury. A 59-year-old woman presented with a 4-week history of multiple erythematous tender nodules on left arm. A year prior, multiple nodules appeared on left hand dorsum, followed by recurrent suppurative nodules in left arm. She has been taking methotrexate and leflunomide for 7 years due to rheumatoid arthritis (RA). Skin biopsy revealed granulomatous inflammation, and NTM polymerase chain reaction test was positive. Furthermore, she had cut her left finger with a knife 14 months ago. Based on these findings, cutaneous NTM infection was diagnosed. Herein, we report a case of cutaneous NTM infection in an immunosuppressed patient with RA, emphasizing differentiating subcutaneous nodules from rheumatoid nodules in RA.

Keyword

Immunosuppression therapy; Nontuberculous mycobacteria; Rheumatoid arthritis