A 46-year-old man was admitted to our hospital because of a fever of unknown origin. The patient had a skin rash, arthralgia, and hepatosplenomegaly. Laboratory tests showed leukemoid leukocytosis, a high serum ferritin level (31,200 ng/mL), and abnormal liver function tests. He was initially diagnosed with adult-onset Still's disease (AOSD). However, imaging studies incidentally detected a cold abscess involving the 11th thoracic vertebra. A biopsy of the abscess revealed histologically

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... matous caseous necrosis, positive for M. tuberculosis by polymerase chain reaction. We present a patient with musculoskeletal tuberculosis (TB) that clinically mimicked AOSD. In TB-endemic countries, extrapulmonary TB should be included in the differential diagnosis of AOSD. (Korean J Med 2014;86:785-790)