Surgical implications of frontoethmoidal pneumosinus dilatans-associated proptosis caused by meningioma

Pneumosinus dilatans (PSD) involves paranasal sinus enlargement without radiologic evidence of localized bone destruction, hyperostosis, or mucous membrane thickening. We discuss the surgical implications of PSD-associated proptosis in patients with anterior skull-base meningioma. A 20-year-old man with proptosis, hypoglobus, and lateral globe displacement had WHO grade I anterior skull-base and orbital meningiomas. Aggressive resection using anterior/medial orbitotomy and an anterior interhemispheric skull-base approach achieved Simpson grade I resection. Postoperatively, his symptoms improved, with no recurrence at 2-year follow-up. Although PSD-associated proptosis is relatively uncommon, it carries important clinical implications in surgical management of skull-base and orbital meningiomas.