Focal organizing pneumonia on surgical lung biopsy: Causes, clinicoradiologic features, and outcomes

Background: Organizing pneumonia (OP) is a histologic pattern that is morphologically distinctive but nonspecific and can be seen in diverse clinical settings. Focal OP has been described as a discrete form of OP, but relatively little is known regarding this clinicopathologic entity. Methods: We sought to clarify the clinicoradiologic presentation, underlying causes, and outcomes associated with focal OP by retrospectively reviewing 26 consecutive cases diagnosed by surgical lung biopsy over an 8-year period from January 1, 1997, to December 31, 2004. Results: All patients presented with an unifocal opacity detected on chest radiography (20 patients) or CT scans (6 patients). At the time of presentation, 10 patients (38%) had symptoms, including cough, shortness of breath, or chest pain; 16 patients were asymptomatic. Contrast-enhancement CT scanning or positron emission tomography (PET) scan was performed in 11 patients, and the results were positive in all. Surgical procedures included wedge resection in 21 patients (81%), segmentectomy in 3 patients (11%), and lobectomy in 2 patients (8%). Three case of focal OP (12%) were related to infections, but the remaining cases were cryptogenic. Follow-up over a median interval of 11 months (range, 1 to 71 months) yielded no recurrence of OP. Conclusions: The radiologic features of focal OP are often indistinguishable from those of lung cancer, and include positivity on contrast-enhancement CT scan and PET scan. Most cases of focal OP are cryptogenic, and infection is identified in a minority of cases. Surgical resection alone appears to suffice in the management of cryptogenic focal OP.