Isolated Tuberculous Myositis: A Systematic Review and Multicenter Cases

OBJECTIVE: To investigate the clinical features and associated underlying conditions of isolated tuberculous myositis (ITBM), a rare extrapulmonary tuberculosis (TB). METHODS: A systematic literature search and a multicenter survey were performed using a triangulation strategy. Data from the identified ITBM cases were extracted and analyzed to determine the underlying conditions, clinical presentations, treatments, and outcomes. RESULTS: Based on the systematic review, we identified 58 ITBM, including 9 pediatric, cases in the literature published from 1981 to 2021 25 (43.1%) immunocompromised and 33 (56.9%) non-immunocompromised patients. Immunocompromised cases had a significant shorter symptom duration (median 30.0 vs. 75.0 days) and a higher prevalence of multilocular involvement (20.8% vs. 0%). Among 24 immunocompromised adult patients, dermatomyositis/polymyositis (DM/PM; n=10, 41.7%) were the most common underlying diseases in adults with ITBM identified in the systematic review. Over the past 20 years, 11 Korean adults with ITBM were identified in the multicenter survey. Of 7 immunocompromised cases, two (28.6%) were DM/PM patients. TB death rate of immunocompromised patients was 0.0% and 5/23 (21.7%) in the pediatric and adult ITBM cases identified in the systematic review, respectively, and 3/7 (42.9%) in survey-identified ITBM cases. CONCLUSION: ITBM has a unique clinical presentation including fever, tenderness, local swelling, overlying erythema, abscess formation and was associated with a grave outcome, especially in immunocompromised hosts. DM/PM was a highly prevalent underlying disease in both systematic review-identified and survey-identified immunocompromised ITBM patients.