A 71-year-old woman with polymyositis presenting with left thigh pain and an intermittent fever was admitted to Osaka Rosai Hospital. We initially diagnosed that her pain and fever were caused by a soft tissue infection because her polymyositis was controlled. She did not respond to various antibiotic therapies. Chest computed tomography demonstrated miliary tuberculosis (TB). Ziehl-Neelsen staining of liver biopsy specimens revealed epithelioid cell granuloma and acid-fast bacilli. Therefore, we finally diagnosed the lesion as TB fasciitis that improved with anti-TB drug therapy. The atypical presentation of TB fasciitis demonstrates the clinical importance of eliminating TB infections in immunocompromised hosts.