Abstract
Background. Spontaneous regression of primary lung cancer is extremely rare. Case. A 55-year-old male presented with cervical lymphadenopathy. A percutaneous aspiration biopsy failed to detect any definite malignant findings, and only necrosis was observed. He also had a mass lesion in the right lung apex. We performed a transbronchial biopsy, but only scar tissue was obtained. A significant reduction in the size of the tumors was subsequently observed without any treatment. Eight months later, new cervical lymphadenopathy appeared, and was diagnosed as poorly differentiated carcinoma by percutaneous aspiration biopsy. The patient underwent right upper lobectomy, which confirmed the diagnosis of the lung tumor as large cell carcinoma. Strongly positive expression of HLA class I and infiltration of CD8-positive cells within the tumor were seen in both the lung and lymph node specimens. During the course of the evaluation and treatment, the white blood cell (WBC) count and serum granulocyte-colony stimulating-factor (G-CSF) level increased in parallel with the disease progression, and immunohistochemical staining also demonstrated G-CSF production in the primary tumor, which met the criterion for a G-CSF-producing tumor. Conclusions. Although the mechanism is unclear, the spontaneous regression of cancer is considered to be closely related to antitumor immune responses, such as positive expression of HLA class I and the infiltration of CD8-positive cells. This case is considered to be an example of the spontaneous regression of a G-CSF-producing large cell carcinoma of the lung.
