An 82-year-old man presented with blood-tinged sputum, dizziness, and a 3 kg weight loss over 6 months. He had been taking medications for hypertension and diabetes, and had had pulmonary tuberculosis 40 years earlier. He quit smoking 13 years earlier, but had a smoking history of 60 pack-years. Written informed consent has been provided by the patient to have the case details and any accompanying images published.
Chest computed tomography (CT) revealed multiple fluid-containing bullae and a contrast-enhancing 2.5 cm mass with a lobulated margin in the right lower lobe of the emphysematous lung (Figure 1A). Histologically, tissue from a percutaneous thoracic needle biopsy of this mass showed that it consisted predominantly of spindle-shaped cells with moderate pleomorphism, hemorrhage, and necrosis. The mitotic rate was four figures in 10 high-power fields. Immunohistochemical staining was positive for desmin and smooth muscle actin, and negative for ALK, Pan-CK, CAM5.2, HMB45, Melan-A, P40, and TTF-1. The pathology and immunohistochemistry findings were consistent with leiomyosarcoma. Whole-body 18F-fluorodeoxyglucose positron emission tomography-CT did not detect any pathologically increased uptake, except above the mass, with a maximum standardized uptake value of 2.24. No specific findings were seen on brain magnetic resonance imaging.
The patient was deemed inoperable medically because of his poor medical condition and old age. The small tumor size and its location at the lung periphery permitted the application of SABR, instead of conventional RT. During the simulation, the patient was immobilized in the supine position with his arms above his head. Respiration-correlated four-dimensional CT was conducted using a Real-Time Position Management system (Varian Medical Systems; Palo Alto, CA, USA) and a 16-slice CT scanner (Brilliance CT Big Bore, Philips Medical Systems, Cleveland, OH, USA). Each of 10 CT images reflected 10% of the respiratory cycle. The clinical target volume was delineated on the CT images for each respiratory phase using the lung window setting. The planning target volume was created by adding a 0.5 cm isotropic setup margin around the internal target volume, which was the sum of the clinical target volumes during all 10 respiratory phases. A volumetric modulated arc therapy plan was created using the Eclipse treatment-planning system (Varian Medical Systems) and 6 MV photons, with inhomogeneity corrections (Figures 1B and C). The dose fractionation scheme was 56 Gy in four fractions delivered every other day in February 2015. SABR was performed on a Novalis Tx system (Varian Medical Systems and Brainlab, Feldkirchen, Germany).
A complete tumor response to SABR was observed on chest CT 2 months after the SABR (Figure 1D). Diffuse consolidation with ground glass opacity in the right lower lobe indicated the development of radiation pneumonitis. He developed a productive cough for about 1 month, but this subsided with conservative management. Follow-up chest CT was repeated every 3 or 4 months, and he is alive with no evidence of disease for 2 years.