Multifocal tuberculous myositis: a case series from a tuberculosis endemic region

Multifocal tubercular myositis is rare but important entity that often mimics autoimmune rheumatic or inflammatory muscle diseases. This study aims to collect and analyse cases of multifocal muscular tuberculosis (TB) reported in tertiary care settings in India.

This retrospective, multicentre, observational study was conducted at two tertiary care centres in India between 2019 and 2025. Patients with confirmed TB and evidence of muscle involvement at ≥2 non-contiguous sites were included. Muscle involvement was confirmed by imaging (CT, MRI, ultrasound, FDG-PET) with or without clinical/myopathic features. Clinical, biochemical, radiological, and treatment data were extracted from records.

Among 74 patients with musculoskeletal TB, six (8.1%) had multifocal muscle involvement. Median age was 42.5 years, with equal sex distribution. The mean diagnostic delay was 13.4 months. Inflammatory markers were elevated (mean erythrocyte sedimentation rate 51.2 mm/hr, C-reactive protein 93 mg/L), while muscle enzymes were normal or mildly elevated. Only one patient (16.7%) had isolated muscle TB; others had lymph node (66.7%), skeletal (50.0%), or pulmonary involvement (33.3%). Two patients had underlying connective tissue diseases, and three (50.0%) were on immunosuppressive therapy at diagnosis. GeneXpert-PCR had an 83% yield from muscle tissue or pus. Clinical and radiological improvement was noted in all cases, three (50.0%) required concurrent immunosuppression.

The consideration of multifocal tubercular myositis in the differential diagnosis of inflammatory myopathies, is paramount to reduce diagnostic delays and improve outcomes. A high index of suspicion, use of advanced imaging, and microbiological confirmation are key to the early diagnosis of this entity.