A 19-year-old man presented with peripheral spondyloarthritis characterized by typical magnetic resonance imaging (Fig. 1). The patient was prescribed 150 mg secukinumab monthly starting in May 2020 after a poor response to sulfasalazine and non-steroidal anti-inflammatory drugs. Before receiving biologic therapy, the patient was screened for latent TB and was found to have a negative QuantiFERON-TB test and a normal chest X-ray. The patient had a good response to secukinumab, and musculoskeletal symptoms improved significantly after several months of treatment.
In April 2022, the patient complained of fatigue, mild fever, productive cough, and weight loss lasting for 2 weeks. Physical examination revealed crackle rales in the left lung and no abnormalities in any other organs. Laboratory results demonstrated an elevated C-reactive protein level of 44 mg/dL and an erythrocyte sedimentation rate of 75 mm. Other hematological and biochemical tests, such as complete blood count, liver enzymes, renal function, glycemia, and thyroid function, were normal. The patient tested negative for human immune-deficiency virus, hepatitis B virus, and hepatitis C virus. Chest X-ray showed left upper lobe consolidation (Fig. 2), and a bronchoalveolar lavage test indicated a negative acid-fast Bacilli smear and detected M tuberculosis, which was found to be sensitive to rifampicin and isoniazid by a line probe assay. Bronchoscopic biopsy demonstrated caseating granulomatous inflammation (Fig. 3).
The patient was diagnosed with active pulmonary TB. The initial treatment for TB was 4 antibiotics: isoniazid, rifampicin, pyrazinamide, and ethambutol. Secukinumab was discontinued due to concerns regarding the reactivation of latent TB. Joint pain and back pain were eased by high doses of non-steroidal anti-inflammatory drugs. After 8 weeks of anti-TB treatment, the patient's fever and respiratory symptoms resolved, and the lesion on the chest X-ray improved. Joint pain and back pain were mostly controlled.