Pituicytoma. Sagittal T1- (A) and contrast-enhanced T1-weighted (B) MR images show a suprasellar enhancing solid lesion (arrows) compressing the third ventricle chiasmatic and infundibular recesses. The neoplasm is predominantly composed of bipolar spindle cells arranged in solid sheets and short fascicles, with elongated nuclei and abundant cytoplasm, often organized in fibrillary, anucleate areas (hematoxylin-eosin staining, original magnification 100×) (C). In some areas, more epithelioid cells with clear-cell cytoplasm are evident (hematoxylin-eosin staining, original magnification 200×) (D). Tumor cells are positive to immunostaining for TTF1 (immunoperoxidase staining, original magnification 100×) (E). Moreover, S100 immunostaining shows strong and diffuse positivity (immunoperoxidase staining, original magnification 200×) (F). The S100 immunoreactivity can lead to a misdiagnosis of schwannoma, which is conversely TTF1-
Ugga, L., Franca, R.A., Scaravilli, A. et al. Neoplasms and tumor-like lesions of the sellar region: imaging findings with correlation to pathology and 2021 WHO classification. Neuroradiology 65, 675–699 (2023). https://doi.org/10.1007/s00234-023-03120-1