Rare Occurrence of an Intraocular Choroidal Solitary Fibrous Tumor/Hemangiopericytoma.

PURPOSE

Tumors previously diagnosed as solitary fibrous tumors (SFT) and hemangiopericytomas (HPC) are characterized by the 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.