Fumihiko Nishimura,Hiroyuki Nakase ,Ichiro Nakagawa ,Kentaro Tamura ,Miho Kakutani ,Ryosuke Matsuda ,Shuichi Yamada ,Yasuhiro Takeshima ,Yasushi Motoyama ,Yoshiaki Takamura ,Young-Soo Park , Malignant Transformation of Craniopharyngioma after Growth Hormone Replacement Therapy Case Reports and Series in Surgery 2020 2733-2241 http://dx.doi.org/10.31487/j.CRSS.2020.01.04 https://www.sciencerepository.org/malignant-transformation-of-craniopharyngioma_CRSS-2020-1-104 Abstract: Background: We present a rare case of malignant transformation of a craniopharyngioma in a patient who received growth hormone replacement therapy. Case Description: A 43-year-old male came to our department with a headache and visual disturbance and was admitted. Brain magnetic resonance imaging (MRI) revealed a giant tumor in the intra- and suprasellar region compressing the optic chiasma. Using a transcranial pterional approach, the tumor was removed as much as possible, with the residual mass removed later with a trans-sphenoidal approach. The initial histopathological diagnosis was adamantinomatous craniopharyngioma. Decompression of the optic chiasma was achieved and visual function improved, though residual tumor tissue remained in the parasellar region, without regrowth seen for more than 24 years. At the age of 67 years, the patient received growth hormone replacement therapy because of a deficiency, then 2 years later the residual tumor began to grow gradually. Trans-sphenoidal surgery was again performed to remove the growing tumor and histopathology results revealed an adamantinomatous craniopharyngioma with malignant transformation. Stereotactic radiation therapy was performed for the residual mass with a total dose of 60 Gy. Presently, 1 year later the patient has a stable condition, and the tumor remains controlled, while follow-up examinations are continuing. Conclusion: A craniopharyngioma may undergo malignant transformation with continuous exposure to administered growth hormone. Close follow-up and imaging examinations are necessary to detect a change, including tumor growth in such cases.Keywords: Malignant transformation, craniopharyngioma, growth hormone