Skull Base Chondrosarcoma Caused by Ollier Disease: A Case Report and Literature Review.

Ollier disease (OD) is a rare, nonhereditary bone disease that is characterized by the presence of multiple enchondromatosis (3 or more) with a typical asymmetric distribution which is mainly confined to the appendicular skeleton. OD's most serious complication is the transformation of an enchondroma into chondrosarcoma. The most common sites for chondrosarcoma are in the pelvic and shoulder bones, the superior metaphyseal and diaphyseal regions of the extremities. However, the cranium is an extremely rare site for chondrosarcoma because of OD.We report the case of a 27-year-old woman who was admitted to our hospital with paroxysmal headaches over 1 month and left ptosis for 2 weeks. Magnetic resonance imaging (MRI) scan revealed a mass was located at the left side of the parasellar area. The mass was surgically removed, and histopathologic examination confirmed chondrosarcoma grade I. During follow-up, more imaging examinations and pathologic examination confirmed the final diagnosis was OD.Intracranial chondrosarcoma caused by OD is extremely rare but should be considered in the differential diagnosis when primary chondrosarcoma is diagnosed. Preoperative diagnosis is challenging, and definitive diagnosis requires immunohistochemical examination and systematic examination of the body. Surgical resection is the most effective therapy for rapid relief of symptoms. For patients with OD with normal intracranial MRI, long-term follow-up is necessary.