Isolated leptomeningeal progression from sinonasal carcinomas: Implications for staging workup and treatment.

PURPOSE: To evaluate the rate and risk factors of isolated leptomeningeal progression in sinonasal carcinomas. METHODS: We retrospectively reviewed imaging and clinical records to determine progression patterns, and estimated rates using the Kaplan-Meier method. We evaluated risk factors using proportional hazard regression. RESULTS: We analyzed 120 patients who received adjuvant or primary radiotherapy for sinonasal carcinomas. Most patients had T4 disease (68%) and underwent surgery (84%) and chemotherapy (72%). Twenty-seven (23%) patients developed distant metastases (DM), including 20 (17%) with isolated DMs. Leptomeningeal progression was the most common site of isolated DMs (n = 9; 45%) with an average disease-free interval of 1.2 years (0.1-4.3 years). High-grade histology (P = 0.0003), intracranial invasion (P < 0.0001), and neuroendocrine histology (P = 0.06) were associated with increased risk. CONCLUSIONS: Isolated leptomeningeal progression is a common pattern of DM in advanced sinonasal carcinomas. We recommend adding cerebrospinal fluid cytology and contrast-enhanced spine MRI to routine staging evaluations for high-risk patients.