PATH-01. SELLAR SOLITARY FIBROUS TUMORS WHO GRADE II AND III: MIMICS OF NON-FUNCTIONING PITUITARY ADENOMAS

Abstract

Abstract Solitary fibrous tumors WHO grade II and III (SFTs II/III) are rare mesenchymal neoplasia accounting for 0.4% of primary central nervous system tumors. SFTs II/III located in the sella turcica region are even rarer and, since the first case described in 1983, only 21 case reports of sellar/suprasellar SFTs II/III (ssSFTs II/III) have been described to this day. We aim to analyze ssSFTs II/III and to demonstrate that can be differentiated from non-functioning pituitary adenomas through pathological examination alone. We analyzed 20 case reports of ssSFTs II/III identified through PubMed and Google searches and a new unpublished case presented at Emory University. ssSFTs II/III are equally represented in both sexes, with 11 cases over 21 occurring in females and the mean age of onset at 46 years old. Clinically, ssSFTs II/III present with compression symptoms related to the tumor location. Headache, visual field defects, and anterior hypopituitarism-related symptoms are frequent chief complaints. As such, almost all cases of ssSFTs II/III had a pre-biopsy working diagnosis of non-functioning pituitary adenomas. The differentiation between SFTs II/III and pituitary adenomas based on imaging findings remains challenging, and surgical biopsies are necessary for a definitive diagnosis. ssSFTs II/III surgical reports describe a unifying trait of a highly vascular tumor adherent to the dura that bleeds profusely after resection. These characteristics are less consistent with a pituitary adenoma. The genetic hallmark of SFTs at all anatomical sites is paracentric inversions at 12q13, fusing the NAB2 and STAT6 genes, with consequent overexpression of STAT6. Pituitary adenomas lack this genetic signature. ssSFTs II/III have an overlapping presentation and similar imaging findings of pituitary adenomas, but different management and prognosis. Hence, it is crucial to include ssSFTs II/III among the pre-biopsy differential of sellar/suprasellar masses identified on imaging. Pathology confirmation is required to guide therapy.