Primary orbital solitary fibrous tumor with an 18-year course of five recurrences and extensive sinonasal metastasis following eyeball enucleation: a case report.

Background: Orbital solitary fibrous tumor (OSFT) represents a rare mesenchymal neoplasm that typically follows an indolent clinical course. However, aggressive variants can exhibit a high propensity for local recurrence, extensive tissue invasion, and delayed metastasis, thereby posing significant challenges for clinical management. The long-term clinical trajectory of highly recurrent OSFT and the optimal multidisciplinary management strategies remain inadequately characterized. Our findings underscore the aggressive potential of recurrent OSFT and propose a comprehensive strategy for long-term surveillance and intervention. Case presentation: We report an exceptionally rare case of a female patient who experienced an 18-years protracted course of OSFT. Initially presenting at age 52 with proptosis and visual impairment, the patient ultimately underwent five surgical interventions due to repeated local recurrences. Despite repeated excisions, the disease progressed relentlessly, necessitating orbital exenteration during the fourth recurrence. Five years after exenteration, a fifth recurrence occurred with extensive paranasal sinus invasion, extending into the frontal, ethmoid, and maxillary sinuses. Histopathological and immunohistochemical analyses consistently confirmed the diagnosis of SFT, characterized by the hallmark by nuclear STAT6 positivity. Notably, the latest recurrence demonstrated increased cellular atypia, elevated mitotic activity, and a Ki-67 proliferation index of approximately 20%. The patient was subsequently treated with endoscopic tumor resection combined with postoperative adjuvant radiotherapy. Conclusion: Orbital solitary fibrous tumor can emerge as a highly aggressive neoplasm characterized by an insidious onset, a protracted recurrent course, and profound local invasiveness. This case strongly correlates repeated recurrences with the anatomical challenges of achieving complete initial resection. To prevent severe structural destruction and improve long-term outcomes, we advocate for early complete surgical excision, the judicious integration of targeted adjuvant radiotherapy for high-risk or locally invasive cases, and stringent, lifelong clinical and systemic imaging surveillance.