CT patterns of organizing pneumonia in patients treated with VEGF/mTOR inhibitors for metastatic renal cell cancer: an observational study

BACKGROUND: Targeted therapies are the standard treatment in patients with metastatic renal cell carcinoma (mRCC) and are known to cause adverse pulmonary events. Organizing pneumonia (OP) with its various manifestations in computed tomography (CT) has therefore lately received more attention. PURPOSE: To describe the spectrum of CT patterns of OP in patients with mRCC receiving targeted therapies. MATERIAL AND METHODS: Seventeen patients with known therapy-related OP were analyzed retrospectively by two blinded radiologists in consensus. Images were scored according to OP patterns that have previously been described. Additionally, the distribution and the predominant imaging pattern in each patient were determined. RESULTS: In our cohort, ground glass opacity was the most common imaging pattern (17/17, 100%) in patients with OP followed by a reticular pattern (12/17, 71%), consolidations (10/17, 59%), nodules (7/17, 41%), crazy paving (5/17, 29%), bronchi(ol)ectasis (4/17, 24%), focal mass (3/17, 18%), and reversed halo (1/17, 6%). The most common imaging pattern was changing multifocal consolidations (8/17, 47%). A bronchocentric and a nodular pattern were found in four patients (24%) each, a progressive fibrotic pattern in none patient, and reversed halo/atoll pattern in one (6%) case. CONCLUSION: OP is the major differential diagnosis to be considered in patients with targeted therapies and pulmonary changes. Knowledge of the variety of imaging findings can facilitate diagnosis.