A Flare of Granulomatosis with Polyangiitis or Reactivation of Pulmonary Tuberculosis? A diagnostic Dilemma

Introduction: Granulomatosis with polyangiitis flare presenting as diffuse alveolar haemorrhage is uncommon in literature. However, excluding pulmonary tuberculosis is crucial before the management of granulomatosis polyangiitis flare, especially in tuberculosis high-prevalence areas.Case presentation: A 12-year-old known patient with well-controlled granulomatosis polyangiitis presented with a history of progressively worsening productive cough, pleuritic-type chest pain, shortness of breath, and recurrent haemoptysis over a two-week duration. She developed respiratory failure following diffuse alveolar haemorrhage and was intubated. After exclusion of possible pulmonary Tuberculosis infection with microbiological and histological investigations, she was successfully treated with intravenous methylprednisolone pulses and intravenous rituximab.Conclusion: Both granulomatosis with polyangiitis flare with diffuse alveolar haemorrhage and pulmonary tuberculosis have similar clinical and radiological manifestations, which are challenging to differentiate. Excluding possible pulmonary tuberculosis with appropriate investigation is crucial before treating GPA flare with DAH.