Acute Fibrinous Organizing Pneumonia: A Case Report and Literature Review.

Acute fibrinous organizing pneumonia (AFOP) is a distinct histopathologic pattern of lung injury with the hallmark feature of intra-alveolar fibrin deposits with associated organizing pneumonia, type II pneumocyte hyperplasia, and a patchy lymphohistiocytic proliferation. We describe the case of a previously healthy 47-year-old man who presented with a 4-day history of worsening dyspnea, cough, and nocturnal fevers and miliary nodules on chest imaging. Subsequently, there was an indication of AFOP when he underwent open lung biopsy. AFOP has been associated with a variety of underlying conditions including rheumatologic diseases, medications, and infections, and several cases were idiopathic. This case highlights the importance for radiologists to be aware of this uncommon pattern of lung injury and to consider it in the differential when encountering bilateral miliary infiltrates on chest imaging.