Diagnostic problems related to acute fibrinous and organizing pneumonia: misdiagnosis in 2 cases of lung consolidation and occupying lesions.

Acute fibrinous and organizing pneumonia (AFOP) is a histological pattern characterized by intra-alveolus fibrinous deposition accompanied with a spectrum of clinical condition. It also presents in other types of lung lesions, thus renders risks to its diagnosis with small biopsies. Here we present 2 cases of lung consolidation and occupying lesions with typical histological presentation of AFOP. One case is tuberculosis presented as massive lung consolidation, initially treated as AFOP, and eventually progressed to bilateral military tuberculosis. The other case presented an occupying mass in the lung which was initially suspected to be an inflammatory mass with AFOP. Lobectomy revealed a poorly-differentiated adenocarcinoma, with AFOP pattern present in the peripheral tissues of the neoplastic mass. In conclusion, we suggest that it is not preferable to diagnose idiopathic AFOP in lung consolidation and occupying lesions before excluding other types of lesions. The diagnostic significance of AFOP should be deliberated.