Post-Infectious Organizing Pneumonia: an Indistinguishable and Easily Misdiagnosed Organizing Pneumonia

Post-infectious organizing pneumonia (OP) is a rare clinical entity associated with nonspecific clinical features and can be easily misdiagnosed. This study aimed to investigate the clinical feature differences between cryptogenic organizing pneumonia (COP) and post-infectious OP.

We retrospectively analyzed clinical data on demographic characteristics, clinical manifestations, laboratory findings, radiological findings, treatments, outcomes, and prognosis of 31 cases of COP and 26 cases of post-infectious OP. Patients were treated in Beijing Chao-yang Hospital between July 2005 and January 2013.

Compared with patients with COP, patients with post-infectious OP are more prone to show fever (88.5% vs. 38.7%, p < 0.05) and crackles (46.2% vs. 6.5%, p < 0.05). The elevation of PCT serum levels is more obvious in the early stage of post-infectious OP (5.24 ± 1.96 vs. 0.28 ± 0.09) and bilateral lung consolidations and patchy shadows are the most common radiological findings (70.2%). Pathogens are more prone to be confirmed within 48 hours after admission and the diagnosis time is longer (10.0 ± 0.8 vs. 7.2 ± 0.4 days). The incidence of mechanical ventilation (50% vs. 19.4%) and the utilization rate of antibiotics are higher (100.0% vs. 70.9%). The dosage (0.58 ± 0.04 vs. 0.78 ± 0.04 mg) and utilization time of glucocorticoids (5.7 ± 0.4 vs. 7.9 ± 0.8 months) are obviously reduced.

The morbidity of post-infectious OP is not uncommon. PCT serum level is helpful in the diagnosis and differential diagnosis, but invasive procedures like bronchoscopic or surgical lung biopsy are the golden-standard methods to confirm diagnosis. Similar to COP, antibiotics are effective in the early stage of post-infectious OP, but glucocorticoids are effective in the late stage. The prognosis of post-infectious OP is good.