Small-cell Lung Cancer Exhibiting Spontaneous Regression

A 56-year-old woman was admitted to our hospital because a chest X-ray and thoracic computed tomography (CT) scan revealed a heterogeneous tumor in the middle mediastinum during a visit to a nearby clinic for a consultation regarding a persistent cough and body weight loss. However, the tumor spontaneously decreased on thoracic CT performed on admission. Subsequently, a biopsy of the tumor using video-assisted thoracoscopy was performed. The pathological findings disclosed the tumor to be small-cell lung cancer with infiltration of CD8-positive T-cells exhibiting spontaneous regression. Cell-mediated immunity, including CD8-positive T-cells, may have relevance to the spontaneous regression of malignant tumors.