Subacromial corticosteroid injections are a well-recognised management for chronic shoulder pain and are routinely used in general practice and musculoskeletal clinics. Mycobacterium tuberculosis (TB) of a joint is a rare presentation in the United Kingdom. International literature exists for cases of reactivated latent tuberculosis following intra-articular corticosteroid injections in a knee; however there are no reports of a primary presentation of undiagnosed TB in a joint following therapeutic corticosteroid injections.

A seventy-four year old lady presented with a one-year history of a painful shoulder, which clinically manifested as a rotator cuff tear with impingement syndrome. Following three subacromial depo-medrone injections, the patient developed a painless “cold” lump which was investigated as a suspicious, possibly metastatic lesion. This lump slowly developed a sinus and a subsequent MRI scan identified a large intra-articular abscess formation. The sinus then progressed to a large intra-articular 5×8 cm cavity with exposed bone (picture available). The patient had no diagnosis of TB but had pathogen exposure as a child via her parents.

The patient underwent three weeks of multiple débridement and intravenous amoxicillin/flucloxacillin to treat Staphylococcus aureus grown on an initial culture. Despite best efforts the wound further dehisced with a very painful and immobile shoulder. Given the poor response to penicillin and ongoing wound breakdown there was a suspicion of TB. After a further fortnight, Mycobacterium tuberculosis was eventually cultured and quadruple antimicrobial therapy commenced. Ongoing débridement of the rotator cuff and bone was required alongside two months of unremitting closed vacuum dressing. The wound remained persistently open and excision of the humeral head was necessary, followed by secondary wound closure. There were no extra-articular manifestations of TB in this patient. At present the shoulder is de-functioned, the wound healed and shoulder pain free.

This unique case study highlights that intra-articular corticosteroid can precipitate the first presentation of Mycobacterium tuberculosis septic arthritis. The evolution of symptoms mimic many other shoulder complaints making confident diagnosis a challenge. The infective bone and joint destruction did not respond to the management described in the current literature. There remains a further management issues as to whether arthroplasty surgery can be offered to post-TB infected shoulder joints.

Taking a TB exposure history is indicated prior to local immunosuppressant injection, particularly in the older age group of western populations and ethnicities with known risk factors.