Muscular tuberculosis of the infraspinatus mimicking a lipoma

Muscular tuberculosis (TB) is a rare manifestation of extrapulmonary TB and often challenging to diagnose due to its non-specific clinical features. A 35-year old housewife presented with a slow-growing swelling over her right upper back for three months with minimal pain. On examination, the swelling was soft, mobile, and fluctuant, confined to the subcutaneous and the intramuscular planes. With a clinical diagnosis of a lipoma, the patient was offered an excision of the swelling. However, intra-operatively the lesion was arising from the infraspinatus with caseous and purulent material. These findings led to a suspicion of muscular tuberculosis. The histopathology and the Gene Xpert polymerase chain reaction (PCR) were consistent with tuberculosis. The patient was started on anti-tuberculosis therapy and had a good outcome on three months follow-up.