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. After this
therapy, pulmonary infiltration developed and was later shown by transbronchial biopsy to be caused by Mycobacterium tuberculosis. The
panniculitis skin lesion became smaller after
prednisolone therapy and was further improved after antituberculosis drugs were added. Reexamination of the previously biopsied skin tissue disclosed
acid-fast bacilli. Reactivation or new
infection of M.
tuberculosis is a current important issue in RA patients, especially
after treatment with disease-modifying
anti rheumatic drugs or antitumor
necrosis factor agents. Mycobacterium-associated lobular
panniculitis should be included in the differential diagnosis of indurated skin disorder in RA patients, and
acid-fast staining or polymerase chain reaction examination of
tuberculosis should be performed routinely on biopsied skin tissue.