Rare Occurrence of an Intraocular Choroidal Solitary Fibrous Tumor/Hemangiopericytoma

Abstract

Purpose: Tumors previously diagnosed as solitary fibrous tumors (SFT) and hemangiopericytomas (HPC) are characterized by the NAB2-STAT6 fusion gene, leading to nuclear STAT6 expression, and are now considered part of one SFT/HPC tumor entity by the 2016 World Health Organization Classification of Tumors of the Central Nervous System. We present the first primary choroidal SFT/HPC with the diagnosis confirmed by STAT6 expression. Procedures: A 51-year-old man underwent enucleation for a choroidal mass, which revealed a spindle cell neoplasm involving the optic nerve, without extrascleral extension. Immunohistochemical stains for S-100, melan-A, tyrosinase, and HMB45 were all negative; however, detection of monosomy 3 by FISH favored a choroidal spindle cell melanoma. Four years later, he presented with hepatic metastases of a spindle cell tumor, and a year later with an epithelioid malignancy involving the calvarium. Results: The calvarial tumor showed nuclear STAT6 immunoreactivity, supporting the diagnosis of SFT/HPC. Retrospectively, the choroidal and hepatic masses were also found to demonstrate nuclear STAT6 expression, supporting the diagnosis of a primary choroidal SFT/HPC with metachronous metastases to the liver and calvarium. Conclusions: This case highlights the significance of considering SFT/HPC in the diagnosis of intraocular spindle cell tumors and the importance of STAT6 immunohistochemistry in the evaluation of such tumors.

Fascin‑1 is associated with recurrence in solitary fibrous tumor/hemangiopericytoma

“…In the same year, the common gene fusion between NAB2 and STAT6 was discovered in SFT/HPC. The 2016 WHO Classification of Tumors of the Central Nervous System designated these tumors, characterized by the NAB2-STAT6 gene fusion, as SFT/HPC in mesenchymal/non-mesenchymal tumors ( 2 , 9 , 33 , 34 ).…”

“…In 2013, three groups reported that SFT and HPC have a common gene fusion between NGFI-A-binding protein 2 (NAB2) and signal transducer and activator of transcription 6 (STAT6) (1,6,7). Thereafter, STAT6, which has dual functions as a signal transducer and as transcription activator in SFT and HPC, was recognized as the highly sensitive and specific immunohistochemical marker for SFT/HPC (2)(3)(4)(5)(8)(9)(10)(11).…”

“…Clinical progression of SFT/HPC is different in each case. For example, we reported one case where it was diagnosed accidentally and treated completely by a successful surgery, whereas in other cases relapse occurred with local recurrence and/or multiple metastases after many years of surgical treatment followed by radiotherapy and/or intensive chemotherapy (1,3,9,10,(12)(13)(14)(15)(16)(17)(18). Regardless of the many attempts that have been made to classify NAB2-STAT6 fusion variants to prognose clinical characteristics of SFT/HPC, any absolute fusion variant related to malignancy has not yet been detected (11,19,20).…”

An intraocular solitary fibrous tumor/hemangiopericytoma with extrascleral extension: Case report and review of literature

“… 2 Intraocular SFT/HPCs are extremely rare, with only six cases previously reported. 3 , 5 , 6 , 7 , 8 , 9 Four of these cases report SFT/HPC arising from the choroid, 3 , 7 , 8 , 9 one reported supraciliary origin, 5 and the sixth reported ciliary body origin of the tumor. 6 None reported extrascleral extension.…”

“…In 2016 the World Health Organization Classification of Tumors of the Central Nervous System was revised to include SFT and HPC as the same neoplasm, now designated as SFT/HPC. 3 On histology, both SFT/HPC show a haphazard or “patternless” architecture, with HPC classically having “staghorn” branching vessels and SFT showing a spindle-cell matrix with “ropey” collagen. SFT/HPC which show a typical SFT pattern and less than 5 mitoses/10 HPF are considered grade I, those with an HPC pattern and less than 5 mitoses/10 HPF are grade II, and those with an HPC pattern and at least 5 mitoses/10 HPF are grade III.…”