LAUSR

BACKGROUND Maffucci syndrome (MS) and Ollier disease (OD) are rare diseases characterized by multiple benign enchondromas. Incidence of skull base (SB) enchondromas and the risk of malignant transformation remain unknown. Most SB lesions are asymptomatic and surgical resection carries significant morbidity. Observation may be a reasonable strategy. We report our experience with observation of probable SB enchondromas in MS/OD patients. METHODS Retrospective review of OD/MS cases with cranial imaging between 1995-2018 at one institution. RESULTS 14 patients were included-3 MS (21.4%) and 11 OD (78.6%). Median age was 28 years (range 11-74) and 57.1% were female. Extracranial chondrosarcoma was reported in 3 (21.4%) patients. Seven (50%) patients with SB enchondroma or chondrosarcoma were identified on initial imaging. In patients with SB lesions, the indications for imaging were: headache (n=3), seizure (n=1), and diplopia (n=1); 2 cases were incidental findings. Most commonly involved structures: petroclival fissure (86%) and clivus (71%). Treatment included observation (6/7) and resection (1/7). Follow-up imaging was available for all SB lesions with a mean interval of 50.7 months (range 5-225) and was negative for progression in all cases. CONCLUSIONS Primary SB lesions in OD/MS patients frequently present in the petroclival junction. Cranial screening and close observation should be considered in MS/OD patients given increased risk of intra-axial intracranial tumors, de novo chondrosarcomas or malignant degeneration of previously known lesions. In asymptomatic patients, observation appears to be a safe strategy in this cohort. Further case accumulation and follow-up is required to better understand the long-term outcomes.