Apparent spontaneous regression of malignant neoplasms after radiography: Report of four cases

INTRODUCTION: On rare occasions, an apparently spontaneous regression of unknown etiology is observed in a neoplasm. We report a series of 4 patients with apparent spontaneous regression of malignant lymphomas after radiography. PRESENTATION OF CASE: All four of the tumors were malignant lymphomas. The regressions occurred between 1 and 2 months after the radiographic examinations. All four patients later underwent relapse and needed additional treatments: surgery, chemotherapy and/or radiation. DISCUSSSION: Four cases had the following features in common: (1) the neoplasms were radiosensitive, (2) the regression occurred after radiography, (3) none of the neoplasms was in the advanced stage, and (4) the doses received through radiographic exposure were a little higher than usual because CT was included for most of the patients. CONCLUSION: We suspect that the apparently spontaneous regression of malignant lymphomas was caused by the small radiation doses received in the radiographic examinations.