Incidence of malignancy in lung lesions initially classified as organizing pneumonia on CT-guided biopsies.

[PURPOSE] Organizing pneumonia is an inflammatory disorder that may co-exist with malignancy in the lung or elsewhere in the body. We aimed to assess patients with a lung biopsy diagnosis of organizing pneumonia for subsequent pathology confirmation of co-existing malignancy.

[METHODS] In this retrospective IRB-approved, HIPAA-compliant study, 1314 consecutive patients who underwent CT-guided lung biopsy for suspected lung cancer or metastatic disease from 02/2014 to 04/2022 at a single tertiary referral hospital were identified. In 98/1314 (7.5%) patients, biopsies showed organizing pneumonia, which represented our study cohort. Clinical outcomes, including follow-up imaging and repeat tissue sampling if performed, were evaluated through chart review. Descriptive statistics were calculated.

[RESULTS] There were 43/98 (44%) females, mean age was 66 ± 14 years, mean lesion size 2.9 ± 2.1 cm, and 11/98 (11.2%) had prior history of malignancy. Of 98 patients initially diagnosed with organizing pneumonia on lung biopsy, 11 (11.2%) were subsequently found to have malignancy. Among these, 6 (54.5%) had pulmonary metastases and 5 (45.5%) had primary lung cancer. Malignancies were confirmed through percutaneous re-biopsy in 3/11 (27%) and bronchoscopic, endoscopic, or surgical procedures in 8/11 (73%).

[CONCLUSION] Malignancy can co-exist with organizing pneumonia in a substantial percentage of initial lung biopsies. Therefore, repeat tissue sampling should be considered when there is high clinical suspicion of malignancy despite an initial histopathological diagnosis of organizing pneumonia. This is especially relevant in lesions that demonstrate FDG avidity on PET/CT or an increase in size on interval imaging, or in instances where the biopsy core sizes are small or where the biopsies have intraprocedural complications.