Acute fibrinous and organising pneumonia (AFOP): a case series highlighting diverse aetiologies and clinical outcomes in three patients

Background Acute fibrinous and organising pneumonia (AFOP) is a rare histopathological pattern of acute lung injury characterised by intra-alveolar fibrin deposition and organising pneumonia. It has diverse aetiologies and highly variable clinical outcomes.Case presentations We report three cases of AFOP from Qatar. Case 1: A 71-year-old man developed AFOP following influenza A (H1N1) infection and achieved complete clinical and radiological resolution with corticosteroid therapy. Case 2: A 52-year-old man with anti-MDA5-positive clinically amyopathic dermatomyositis developed rapidly progressive AFOP and died despite aggressive multi-modal immunosuppression. Case 3: A 51-year-old woman presented with AFOP in the setting of Staphylococcus aureus bacteraemia, which unmasked underlying chronic myeloid leukaemia; she achieved full radiological resolution with corticosteroids.Conclusions This case series highlights the wide clinicopathologic spectrum of AFOP, the critical importance of early histological diagnosis, identification of underlying triggers, and the highly variable prognosis depending on aetiology. Early lung biopsy and tailored therapy remain essential in the management of this uncommon condition.