脊索腫様膠腫と鑑別を要した第三脳室限局型BRAFV600E変異陽性頭蓋咽頭腫の1例

Craniopharyngioma Mimicking Chordoid Glioma

術前画像で脊索腫様膠腫との鑑別が困難であった35歳女性の第三脳室限局型頭蓋咽頭腫を経験した。第三脳室内限局型頭蓋咽頭腫は類円形の腫瘍形状，扁平上皮乳頭型の組織，BRAF^V600E変異陽性が特徴で，石灰化と囊胞形成は稀である。過去に脊索腫様膠腫と類似した画像所見を呈することに言及した報告はない。本症例はBRAF^V600E変異陽性にもかかわらず病理学的にエナメル上皮腫型を示した稀有な症例であり，治療方法の選択という点で，分子診断の重要性を示唆した。

Abstract

Entirely intrinsic third ventricular craniopharyngiomas showed characteristics of a round/oval shaped tumor, with rare calcification and cyst formation, and pathologically squamous-papillary type with a positive BRAF^V600E mutation. We report an extremely rare case of entirely intrinsic third ventricular craniopharyngioma, pathologically adamantiomatous but with BRAF^V600E mutation genetically, developed in a 35-year-old female. It was oval-shaped, with no calcification or cyst, and showed homogeneous enhancement. As shown in this case, it was difficult to differentiate this pathology from chordoid glioma of third ventricle, and the difficulty of this differential diagnosis has not been well documented in previous studies. Our case further implied the importance of molecular diagnosis for subclassification of craniopharyngioma. The BRAF^V600E-mutated craniopharyngioma could be the target for the development of treatment with preoperative BRAF-inhibitors. Therefore, differentiation between entirely intrinsic third ventricular craniopharyngiomas and chordoid glioma could be new issue. In this report, we discuss about the preoperative differential diagnosis from chordoid glioma and the literature review.

(Received 12 August, 2021; Accepted 21 September, 2021; Published 1 February, 2022)