Mizuki Nishino MD, Presenter: Consultant, Bristol-Myers Squibb Company

Erica N. Boswell, Abstract Co-Author: Nothing to Disclose

Hiroto Hatabu MD, PhD, Abstract Co-Author: Research Grant, Toshiba Corporation Research Grant, AZE, Ltd Research Grant, Canon Inc

Irene M. Ghobrial MD, Abstract Co-Author: Nothing to Disclose

Nikhil H. Ramaiya MD, Abstract Co-Author: Nothing to Disclose

To determine the frequency of drug-related pneumonitis during mTOR inhibitor therapy in Waldenstrom macroglobulinemia (WM) patients, and investigate the imaging characteristics and patterns of pneumonitis.

Forty patients (23 males and 17 females, age:43-84) with WM treated in 2 trials of mTOR inhibitor, everolimus, who had baseline and at least one follow-up chest CT available for review were retrospectively studied. All chest CT scans were reviewed for abnormalities suspicious for drug-related pneumonitis by consensus of 3 radiologists, evaluating 1) extent in upper, middle and lower lungs (none, <5%, 5-25%,25-50%, >50%), 2) distributions (peripheral, diffuse, central or mixed; and upper, lower, diffuse, multifocal or focal), and 3) specific CT findings. The cases with definite or probable drug-related pneumonitis were classified using ATS/ERS classification of interstitial pneumonia based on CT features. 

Drug-related pneumonitis was noted in 23 patients (58%)(definite in 19; probable in 4). Median time between therapy initiation and the onset of pneumonitis was 5.5 months. Lower lungs were involved in all 23 patients, with higher extent than other zones (median extent: upper:<5%; middle:5-25%; lower:25-50%; p<0.001). The distribution was most commonly peripheral and lower in 11 (48%), and mixed and multifocal in 10 patients (44%). Findings were bilateral in 20 (87%). GGOs and reticular opacities were present in all 23 patients, with consolidation in 12, traction bronchiectasis in 2 and centrilobular nodularity in 1 patient. The pattern of pneumonitis was classified as COP in 16 and NSIP in 7, while overlapping features of COP and NSIP were noted in 7 patients (5 in COP group and 2 in NSIP group). No significant differences were noted in clinical characteristics between patients with and without pneumonitis (p>0.34).

Drug-related pneumonitis was noted on CT in 58% of WM patients treated with mTOR inhibitor. Most common findings were bilateral GGOs and reticular opacities, with or without consolidation, in peripheral and lower lungs. Patterns of CT findings simulate COP and NSIP. 

Awareness of the high incidence and characteristic imaging features of drug-related pneumonitis during mTOR inhibitor therapy contribute to accurate radiologic interpretation and patient management.

Nishino, M, Boswell, E, Hatabu, H, Ghobrial, I, Ramaiya, N, Drug-related Pneumonitis during mTOR Inhibitor Therapy in Patients with Waldenstrom Macroglobulinemia.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14045432.html