Mycobacterium-associated lobular panniculitis, mimicking a rheumatoid nodule in a patient with rheumatoid arthritis.

Mycobacterium-associated lobular panniculitis can mimic a rheumatoid nodule and has been seldom reported in rheumatoid arthritis (RA). We describe a 69-year-old woman with RA who presented initially with fever and an indurated skin lesion on the right thigh. Lobular panniculitis was diagnosed after biopsy and was then treated with prednisolone.