Radiological misdiagnosis of intracranial solitary fibrous tumor: a case report STAT6 immunohistochemistry resolves the diagnostic challenge.

INTRODUCTION AND

IMPORTANCE

Intracranial solitary fibrous tumors (SFTs) are rare mesenchymal neoplasms that often present as dural-based masses and can mimic meningioma on imaging. Central nervous system SFTs carry a clinically important risk of recurrence even after gross total resection, necessitating accurate diagnosis and long-term surveillance. Nuclear STAT6 immunohistochemistry is a highly accurate diagnostic marker for SFT and a surrogate for the underlying NAB2-STAT6 fusion.

CASE PRESENTATION: A 45-year-old male presented with 4 weeks of progressive right-sided headache. Magnetic resonance imaging demonstrated a 6.0 × 4.0 × 5.5 cm well-circumscribed dural-based mass in the right occipito-parietal region with intermediate T1 signal and heterogeneously high T2 signal, including a "yin-yang" pattern. A broad dural attachment was present without a dural tail. The lesion was initially interpreted as meningioma. Contrast-enhanced sequences were not obtained due to patient refusal and financial constraints. The patient underwent gross total resection via right occipito-parietal craniotomy on 15 March 2025, without complications.

CLINICAL DISCUSSION: Histopathology showed a "pattern less pattern" with alternating cellularity, spindle cells, and prominent branching staghorn vessels. Immunohistochemistry demonstrated strong nuclear STAT6 positivity with EMA and SSTR2A negativity, supporting SFT (WHO grade 1) and excluding fibrous meningioma. Headaches resolved completely with full neurological recovery by April 2025, and the patient remained asymptomatic at follow-up in June 2025.

CONCLUSION

This case highlights the limits of imaging-based diagnosis in dural-based masses and supports systematic STAT6 immunohistochemistry to establish SFT diagnosis, guide counseling on recurrence risk, and plan surveillance. This case report was prepared according to SCARE 2025 guidelines.