Malignant progression of cerebellopontine angle solitary fibrous tumors following radiation: illustrative case

BACKGROUND: Intracranial solitary fibrous tumors (ISFTs) are rare mesenchymal tumors originating in the meninges and constitute a heterogeneous group of clinical and biological behavior. Benign histotypes, such as hemangiopericytomas are now considered as a cellular phenotypic variant of this heterogenous group of rare spindle-cell tumors. IFSTs are poorly recognized and remain a diagnostic challenge due to rarity and resemblance to other brain tumors. Previously, IFSTs were thought to pursue a slow, indolent, and nonaggressive course, however, a growing body of literature based on longer follow-up demonstrates an unpredictable clinical course and an uncertain diagnosis. OBSERVATIONS: A rare case report of malignant transformation of IFST following radiation therapy is reported. In this case a 60-year-old female who underwent gross total resection of the cerebellopontine angle tumor with histopathology consistent with solitary fibrous tumor followed by salvage stereotactic radiosurgery, presented with another recurrence after 2 years of surgery. The authors performed complete removal of the tumor with pathology now consistent with malignant solitary fibrous tumor. A recent follow-up magnetic resonance imaging did not show any recurrence or residual tumor, and the patient reports a generalized well-being. LESSONS: This report will help to understand the natural history and unusual clinical behavior of these intracranial tumors.