Abstract Although the human central nervous system used to be considered relatively resistant to the carcinogenic action of ionizing radiation, several lines of evidence now document a high incidence of secondary tumors in irradiated patients. The numerous reports of radiation-induced cerebral meningiomas generally distinguish those induced by high-dose radiation from those induced by low-dose radiation. We describe the case of patient who underwent subtotal resection of a chromo- phobe pituitary adenoma at the age of 18 years, who was suc- cessively treated by conventional fractionated radiotherapy with gamma rays emitted by a source of 60 Co until a total dose of 41 Gy. Over the next 30 years the patient experienced all the known late effects of radiation, including panhypopituitarism, cranial-nerve deficits (II, III and VI), massive radiation necro- sis involving the left cerebral hemisphere and causing right hemiparesis and aphasia and, ultimately, an atypical tentorial meningioma with early recurrence after total resection. Key words Pituitary adenoma • Radiotherapy • Meningioma Introduction Radiation-induced cerebral meningiomas are now a well- known clinical entity [1–6]. Consensus opinion distinguish- es meningiomas induced by low-dose irradiation [6, 7] for cutaneous lesions of the head (including tinea capitis and vascular nevi) from those induced by high-dose irradiation [8–13] for radiosensitive neoplasms. Despite slight epidemi- ological differences, including the incidence, location and latency of development, both categories tend towards bio- logical aggressiveness. Among the numerous possible com- plications of radiation therapy, radiation-induced menin- giomas are generally the latest to develop [14]. We report the case of a patient who underwent subtotal removal of a chro- mophobe adenoma followed by radiotherapy at the age of 18 years. During the next 30 years, the patient experienced all the typical post-radiation complications, culminating in a highly aggressive, recurrent tentorial meningioma. Case report In April 1964, an 18-year-old man underwent subtotal resec- tion of a chromophobe pituitary adenoma. No peri- or post- operative complication occurred. Due to the presence of a parasellar remnant of the tumor, the patient was post-opera- tively submitted to radiotherapy with gamma rays emitted by a source of 60 Co; the total dose of 41 Gy was delivered in 23 daily fractions of 1.8 Gy five days per week. The treated vol- ume, including the pituitary fossa and the parasellar region, was irradiated using two 5x5 cm lateral opposed fields. During the ensuing years, the patient had a worsening bilateral defect in visual acuity and, in 1980, developed pro- gressive panhypopituitarism requiring hormone replacement therapy with thyroxin, cortisol and testosterone. Magnetic resonance imaging (MRI) performed in 1990 disclosed dif- fuse encephalomalacia within the left hemisphere and an empty sella. Neurol Sci (2002) 22:463–467 A. Santoro • G. Minniti • S. Paolini • E. Passacantilli P. Missori • A. Frati • G.P. Cantore Atypical tentorial meningioma 30 years after radiotherapy for a pituitary adenoma CASE REPORT © Springer-Verlag 2002 Received: 13 December 2000 / Accepted in revised form: 19 November 2001 A. Santoro () • S. Paolini • E. Passacantilli A. Frati • G.P. Cantore Neurosurgery Unit I Department of Neurological Sciences La Sapienza University of Rome Viale dell’Università 30a, I-00185 Rome, Italy P. Missori Neurotraumatology Unit Department of Neurological Sciences La Sapienza University of Rome Rome, Italy G. Minniti Neurosurgery Unit IRCCS - Neuromed La Sapienza University of Rome Pozzilli (IS), Italy