A 42-year-old woman presented with a 1-week history of swelling and pain in the fifth finger of her left hand. She reported no related trauma. She had systemic lupus erythematosus and was being treated with mycophenolate mofetil and prednisone. Physical examination of the affected finger revealed soft-tissue swelling, with erythema and warmth, that was most prominent between the proximal and distal interphalangeal joints, sparing the fingertip (Panel A). Radiography and magnetic resonance imaging revealed swelling of soft tissue but no bony abnormalities. Examination of a biopsy specimen of the deep dermis after Fite staining revealed numerous acid-fast bacilli (Panel B, arrow). Culture of a tissue sample grew Mycobacterium tuberculosis. Findings on radiography of the chest were normal. The patient had undergone a purified protein derivative skin test before starting immunosuppressive therapy; the result was negative. Further investigation revealed that the patient’s husband, who had recently traveled to China, had a cough that developed soon after his return home. He subsequently received a diagnosis of active pulmonary tuberculosis. Although infection of the finger is a rare extrapulmonary manifestation of tuberculosis, it is an important consideration in immunosuppressed patients. This patient was treated with a four-drug antituberculosis regimen for a total of 9 months and had complete resolution of her symptoms.