Histopathology and molecular characterisation of intrauterine-diagnosed congenital craniopharyngioma.

Abstract

Adamantinomatous craniopharyngiomas (aCPs) are complex epithelial neoplasms that arise from the progenitors of the pituitary gland. Although benign, these tumours can be locally aggressive invading vital neighbouring structures such as the hypothalamus, the cranial and optic nerves. Congenital forms of aCPs diagnosed during foetal development are very rare. The purpose of this article is to present with a histopathological and molecular characterisation of congenital craniopharyngioma. Here we report a case of in utero diagnosed aCP, detected at 21 weeks of gestation by ultrasound, visualised by MRI at 22 weeks and histologically diagnosed at 23 weeks. We provide with histopathological characterisation of rare form of congenital aCPs. Detailed examination of the tumour reveals the classical histological hallmarks of aCPs with the presence of stellate reticulum, palisading epithelium, wet keratin and calcification deposits. The tumour demonstrated complete absence of all pituitary hormones and the absence of the neuroendocrine marker, synaptophysin. Immunohistochemistry against β-catenin revealed occasional cells with nuclear-β-catenin localisation and the presence of pituitary progenitors positive for SOX9 and SOX2. Targeted Sanger sequencing revealed no genetic variants in oncogenes CTNNB1 and BRAF, previously associated with CP. In this article, we provide with in-depth molecular and histological characterisation of in utero aCP due to an unknown driving mutation that could represent a sub-cohort of congenital aCPs.