Tumor-to-tumor metastasis from pituitary carcinoma to radiation-induced meningioma.

Radiation-induced meningioma and pituitary carcinoma are both uncommon. Tumor-to-tumor metastasis (TTM) from pituitary carcinoma to meningioma, to our knowledge, has not been previously reported. A 67-year old man presented with a previous history of transcranial subtotal resection of pituitary adenoma, at the age of 36, followed by radiotherapy. The follow-up was uneventful for the following 31 years. The patient presented with worsening sight and numbness of the right arm. Three separate lesions were found on MRI. Histological examinations revealed pituitary carcinomas and TTM from pituitary carcinoma to meningioma. A constant surveillance is necessary for patients with pituitary tumor, especially those followed by radiotherapy.