Tuberculosis in APML with Persistent Pleural Thickening: A Case Report Chepsy Cherian Philip1, Bobby Abraham1, Sreehari Rajasekharakurup1, Aakash Chozakade1,

Background: Patients with acute promyelocytic leukemia (APML) undergoing induction therapy are severely immunocompromised and prone to opportunistic infections. Tuberculosis (TB), though less commonly considered, can complicate the clinical course, particularly in endemic regions. Objectives: To emphasize the need to consider extrapulmonary TB in APML patients with persistent fever and non-resolving pleuro-pulmonary abnormalities. Methodology: An APML patient receiving arsenic trioxide (ATO) and all-trans retinoic acid (ATRA) developed persistent high-grade fever. High-resolution computed tomography (HRCT) and microbiological evaluation were performed. TB DNA was detected from mediastinal lymph nodes. Due to hepatic and renal dysfunction, a modified anti-tubercular treatment (ATT) regimen was initiated. Serial HRCT scans from February 17 to February 25, 2025 were used for follow-up. Results: Initial HRCT revealed right pleural effusion, adjacent lung collapse, bilateral centrilobular nodules, and mediastinal lymphadenopathy. Follow-up imaging showed marked reduction in pleural effusion with persistent pleural thickening and minimal residual air near the drain site, suggesting an ongoing infectious process. The patient demonstrated clinical improvement with continued modified ATT and APML-directed therapy. Conclusion: Persistent pleural thickening despite decreasing effusion in immunocompromised APML patients should raise suspicion of tuberculosis. Early microbiological confirmation, serial imaging, and multidisciplinary management are crucial for timely diagnosis and favorable outcomes, particularly in TB-endemic settings.