Synchronous organizing pneumonia after sequential three-dimensional radiotherapy for three lung metastases from hepatocellular carcinoma: a case report

Radiation-induced lung injury has been reported after postoperative radiotherapy for breast cancer (1-4); currently, it is a well-known complication of thoracic radiation for lung, esophageal, and hematologic malignancies. The incidence of radiation-induced pneumonitis, mostly of grade 2 or less, ranges from approximately 10% to 30%, and it is manageable (5,6). Radiation-induced lung injury can be categorized into radiation pneumonitis (RP) and organizing pneumonia (OP) (7). OP included RP in the broad sense, but since Crestani et al. (7) reported OP in 1998, several authors have described the features of OP, which differ from those of RP (8,9). Differences between RP and OP have been reported in terms of the time to appearance, predictive factors, expression mechanism, and migration of lung infiltration (1-3). However, to the best of our best knowledge, no author has demonstrated the time to OP appearance after sequential radiotherapy for ipsilateral lung tumors in the second radiotherapy cycle same patient. In this rare case, a woman in her 70s with three lung metastases developed OP synchronously in each irradiated area after sequential three-dimensional radiotherapy (3D-CRT)