Tuberculous myofasciitis in dermatomyositis

Extraspinal musculoskeletal tuberculosis (TB) was an uncommon manifestation with a frequency about 1 to 2% in all TB patients. According to the report, tuberculous arthritis and osteomyelitis remained the two leading etiologies, while others constituted less than 2% of all extraspinal musculoskeletal tuberculous infections; less than 0.04% of those who suffered from TB were represented as extraspinal musculoskeletal tuberculous infections, neither tuberculous arthritis- nor osteomyelitis-associated. We presented one extremely rare case of primary tuberculous myofasciitis manifesting painful swelling on the left thigh without previous history of tuberculous infection in a patient with dermatomyositis. We also lodged several predisposing symptoms, such as gradually enlarging swelling of extremity within months and proximal muscle painful weakness with prompt response to steroid, which may help early diagnosing of analogous extraspinal musculoskeletal tuberculosis in dermatomyositis patients; and seasonable administrating of anti-TB agents could prevent deterioration in advance.