Solitary fibrous tumor with aneurysmal bone cyst–like change in the middle cranial fossa: illustrative case

BACKGROUND: Solitary fibrous tumor (SFT) is a rare mesenchymal tumor known for its propensity for recurrence and metastasis. Furthermore, aneurysmal bone cyst (ABC) is a benign osteolytic lesion. ABC-like areas can be seen in bone tumors that have undergone hemorrhagic cystic change. They are formed by disruptions in the osseous circulation caused by the associated lesion. The most common associated lesions are giant cell tumor, chondroblastoma, osteoblastoma, osteosarcoma, chondromyxoid fibroma, and fibrous dysplasia. There has been no reported case of SFT being the associated lesion. OBSERVATIONS: A 42-year-old woman presented with a 6-month history of headache and impaired memory. Radiological examinations revealed a 50-mm cystic lesion with multiple fluid levels arising from the left temporal bone. Total resection of the tumor was conducted, and postoperative course was uneventful. Histopathological examination was consistent with SFT with ABC-like change. LESSONS: This is the first documented case of SFT with ABC-like change in the cranial fossa. This should be considered a differential diagnosis when treating a lesion in the cranial fossa, such as in this case, to achieve complete resection of the tumor and have close follow-up postoperatively.