Imaging of pituitary tumors: an update with the 5th WHO Classifications—part 2. Neoplasms other than PitNET and tumor-mimicking lesions

Abstract

Many types of tumors can develop in the pituitary gland. In the recently revised 5th editions of the World Health Organization (WHO) classifications (2021 WHO Classification of Central Nervous System Tumors and the 2022 WHO Classification of Endocrine and Neuroendocrine Tumors), various changes have been made to the tumors other than pituitary neuroendocrine tumor (PitNET)/pituitary adenoma, as well as PitNET. Adamantinomatous craniopharyngioma and papillary craniopharyngioma are now considered separate tumors in the 5th edition of the WHO classification. Tumors positive for thyroid transcription factor 1, a marker of posterior pituitary cells, are now grouped together in the pituicyte tumor family in the 5th edition of the WHO classification of Endocrine and Neuroendocrine Tumors. Poorly differentiated chordoma is newly listed in the 5th edition of the WHO Classification of Endocrine and Neuroendocrine Tumors. In this paper, we present the latest WHO classification of pituitary tumors (adamantinomatous craniopharyngioma, papillary craniopharyngioma, pituitary blastoma, pituicyte tumor family, tumors of pituitary origin other than those of the pituicyte tumor family, germinoma, meningioma, chordoma, metastatic tumors, lymphoma, and pituitary incidentaloma), review diseases requiring differentiation from tumors (pituitary abscess, hypophysitis, pituitary hyperplasia, Rathke’s cleft cyst, arachnoid cyst, and aneurysm), and discuss diagnoses based on imaging findings.

Neuroimaging of hypophysitis: etiologies and imaging mimics

“…There are two distinct craniopharyngiomas: adamantinomatous and papillary craniopharyngioma, both of which are regarded as CNS WHO grade 1 in 2021 WHO classification [ 40 ]. Although these craniopharyngiomas have been regarded as subtypes in the previous WHO classifications, they are now recognized as distinct tumor types based on the distinct histologies and driver mutations [ 40 , 47 , 48 ]. Adamantinomatous craniopharyngioma is a mixed solid and cystic squamous epithelial tumor with stellate reticulum and wet keratin, characterized by activating CTNNB1 mutations [ 40 ].…”

“…15 ) [ 55 ]. Germinoma typically shows hyperdensity on CT and restricted diffusion on MRI [ 48 , 60 ]. Contrast enhancement tends to be heterogeneous in mixed germ cell tumors.…”

Value of Quantitative Susceptibility Mapping in Clinical Neuroradiology

“…11) and hypothalamus, and occasionally in the basal ganglia, thalamus, brainstem, and spinal cord. Germinomas are primarily tumors of young patients, with most patients being under than 20 years old at the time of diagnosis 83 . Germinoma in the pineal region shows a marked male preponderance, whereas that in the suprasellar region shows no clear gender preponderance.…”

From pituitary adenoma to PitNET: it is time to discuss PitNET/pituitary adenoma

“…The 5th edition of the WHO Classifications (2021 World Health Organization Classification of Central Nervous System Tumors and 2022 World Health Organization Classification of Endocrine and Neuroendocrine Tumors) has made significant changes, including classification of tumors based on cell lineage as determined by expression of transcription factors, hormones, and other biomarkers [1]. Faced with many updates as described in the articles [2,3], it is important for radiologists to understand the pros and cons of these updates.…”