Radiation injury to the lung caused by yttrium-90 resin microspheres (SIR-Spheres) diagnosed by transbronchial lung biopsy

Objectives Yttrium-90 (90Y) is a radioactive isotope of yttrium used in transarterial radioembolization (also known as selective internal radiation therapy) of hepatocellular carcinoma and metastases to the liver. Although injury to the gastrointestinal tract due to escape of 90Y microspheres beyond the intended target neoplasm has been reported in the pathology literature, lung toxicity caused by 90Y microspheres has only rarely been documented. Methods A 66-year-old woman with a history of ovarian serous carcinoma metastatic to the liver was treated with radioembolization of a liver metastasis with 90Y SIR-Spheres (Sirtex SIR-Spheres Pty Ltd) via the right hepatic artery. A few days later, she developed shortness of breath and was subsequently found to have bilateral evolving consolidations and ground-glass opacities on serial chest computed tomographic imaging. Results Transbronchial biopsy of the left lower lobe showed organizing acute lung injury along with rare eosinophils and 2 90Y microspheres. The patient was treated with corticosteroid therapy with significant clinical improvement. Conclusions This is the first report of a case in which transbronchial lung biopsy led to diagnosis of 90Y-related radiation lung injury in a patient in whom this diagnosis was not previously suspected clinically or radiologically. We recommend adding 90Y to the list of etiologies of acute lung injury with eosinophils. Pathologists should familiarize themselves with the histologic appearance of 90Y microspheres because identification of these structures in the lung can be diagnostic.