Pediatric Mycobacterium Tuberculosis Infection Involving the Ankle: A Case Report

Extrapulmonary tuberculosis is relatively rare, and osteoarticular tuberculosis involving the ankle joint is particularly uncommon. We report a 10.5-year-old, previously healthy male patient who initially presented to the trauma surgery department with a 2-month history of swelling, pain, and limited mobility of the left ankle following minor trauma. Blood tests, including tests to determine blood cell counts, C-reactive protein level, and the erythrocyte sedimentation rate, bacterial and fungal cultures, and T-cell spot tests for tuberculosis (T-SPOT.TB) were performed. B-ultrasound-guided aspiration of the infected area was carried out, which included two surgeries for extensive irrigation, debridement, and drainage. A pus sample was sent for routine bacterial culture and an acid-fast bacillus test, and the bone and soft tissue samples were sent for pathological biopsy and the detection of Mycobacterium tuberculosis by sequencing and rifampicin resistance analysis. The empirical antibiotic was administered for 1 week, followed by linezolid and rifampicin for anti-infection treatment. Ten days later, the T-SPOT.TB test result was positive. Gene sequencing detected the M. tuberculosis complex at "very low levels" with no detection of rifampicin resistance, and the pathological report revealed "chronic necrotizing granulomatous inflammation." After the diagnosis of M. tuberculosis infection was confirmed, the patient was started on appropriate antituberculosis therapy with the isoniazid, rifampicin, pyrazinamide, and ethambutol (HRZE) regimen, and the function of the ankle joint was followed up in the outpatient clinic. This case serves as a reminder for clinicians to consider M. tuberculosis infection in children presenting with atypical ankle swelling and pain.