Mycobacterium tuberculosis infectious monoarthritis in a paediatric patient

Abstract

Mycobacterium tuberculosis is uncommon in the USA, and when it is diagnosed, it is usually in adult patients with identifiable risk factors presenting with pulmonary manifestations of the disease. Paediatric tuberculosis is rare, and a minority of those cases can present with isolated extrapulmonary infection. When the musculoskeletal system is involved, there are often no constitutional symptoms, and it can resemble other infectious and inflammatory processes. Diagnosis is challenging, and delay leads to irreversible destructive osteoarticular changes. A prompt diagnosis requires a high index of suspicion. This report presents a case of successfully diagnosed paediatric M. tuberculosis monoarthritis of the knee to highlight these challenges.

Keywords: Bone and joint infections; Orthopaedics; TB and other respiratory infections.

Figure 1

Sagittal stir sequence MRI demonstrating right knee effusion extending into the suprapatellar pouch with associated synovitis and heterogeneous intracapsular material.

Figure 2

Courtesy of Dr Brett Kurpiel, University of Virginia pathology resident physician. High-power magnification showing a necrotising granuloma within the reactive synovial tissue. Note the numerous giant cells palisading around the granuloma with an eosinophilic, necrotic centre. Abundant lymphocytes, neutrophils and macrophages are present (H&E, 200× original magnification).