Radiation-induced pneumonitis in the "nonirradiated" lung.
OBJECTIVE
To describe six cases of radiation-induced organizing pneumonitis occurring outside the direct radiation field and to review clinical, radiologic, and histologic aspects of this entity.


METHODS
We present detailed case reports of six women, with a mean age of 62.8 years (range, 50 to 75), who had received radiation therapy (mean dose, 6,560 cGy) for breast cancer.


RESULTS
From 6 to 17 months (mean, 8.8) after the completion of radiotherapy, recurrent and migrating lung infiltrates were detected outside the radiation field in the six study patients. Three patients had pronounced respiratory symptoms, whereas the rest were minimally symptomatic or asymptomatic. Thoracic computed tomography showed dense alveolar infiltrates. Bronchoalveolar lavage in two patients revealed lymphocytosis (25% and 19%), and lung biopsy in five patients demonstrated a histologic pattern consistent with bronchiolitis obliterans organizing pneumonia. Even though the symptomatic patients showed prompt resolution of their symptoms and roentgenographic abnormalities after systemic corticosteroid therapy, the lung infiltrates recurred after corticosteroid therapy was discontinued.


CONCLUSIONS
These six cases, including their prompt response to corticosteroid therapy, provide additional evidence that irradiation damages lung tissue outside of the direct treatment field and suggest that an immunologically mediated lymphocytic alveolitis may be responsible for the recurrent migratory organizing pneumonitis.
Arbetter
K R
KR
Department of Internal Medicine, Mayo Clinic Rochester, MN 55905, USA.
Prakash
U B
UB
Tazelaar
H D
HD
Douglas
W W
WW
D000230:Adenocarcinoma / Q000532:radiotherapy*; D000368:Aged; D001943:Breast Neoplasms / Q000532:radiotherapy*; D001992:Bronchoalveolar Lavage Fluid; D018549:Cryptogenic Organizing Pneumonia / Q000000981:diagnostic imaging / Q000188:drug therapy / Q000209:etiology* / Q000276:immunology; D005260:Female; D006801:Humans; D008218:Lymphocytosis / Q000209:etiology; D008875:Middle Aged; D011014:Pneumonia / Q000000981:diagnostic imaging / Q000188:drug therapy / Q000209:etiology* / Q000276:immunology; D011832:Radiation Injuries / Q000209:etiology* / Q000276:immunology; D011878:Radiotherapy / Q000009:adverse effects; D014057:Tomography, X-Ray Computed