Abstract
A 74-year-old male underwent chest CT during the investigation of a gallstone, which incidentally revealed a right apical 5-cm mass. Bronchoscopy was performed, revealing no malignancy. Two months later, FDG-PET examination was performed, showing abnormal FDG accumulation in the right apical mass and multiple liver nodules. Because fever-up and liver function abnormality occurred shortly after the FDG-PET examination, the patient was treated with antibiotic therapy, and the liver nodules subsequently disappeared. At this time point, the size of the right apical mass decreased from 5 to 3 cm in the maximum diameter. The lesion was followed by CT 4 months later, revealing re-enlargement of the mass to 4 cm in maximum diameter. Bronchoscopy was performed again, and the cytology revealed malignancy. We performed a right upper lobe lobectomy. The tumor was adhered to the apical parietal pleura, and it was excised together with the tumor. The pathological diagnosis was a poorly differentiated squamous cell carcinoma, pT3N0M0 stage IIB. The postoperative course has remained uneventful, and he has been followed-up for 13 months with no evidence of recurrence. Spontaneous regression of a non-small cell lung cancer is rare, and the mechanism remains unclear. It may be one possibility that immune system activation due to the liver abscesses induced the spontaneous regression of the lung tumor in this case.
