Epithelioid/clear cell variants of solitary fibrous tumor in the oral cavity: Diagnostic challenges and the critical role of STAT6 immunohistochemistry

Herein, a rare case of oral solitary fibrous tumor (SFT) composed predominantly of epithelioid/clear cells is reported. This unusual variant lacked the characteristic spindle cell proliferation and staghorn-type vasculature typically seen in SFT and instead showed nuclear atypia and increased mitoses, creating a diagnostic challenge. Despite these atypical features, tumor cells showed diffuse and intense nuclear signal transducer and activator of transcription 6 (STAT6) expression, confirming the diagnosis. This case highlights the importance of STAT6 immunohistochemistry as a frontline diagnostic tool for oral tumors with SFT in the differential diagnosis, even with misleading histomorphological features.