A 68-year-old white man presented with progressive mental status changes, which had been noted by relatives over the preceding 3 weeks. Five months before admission, he had complained of chronic headaches and had undergone a computed tomographic (CT) scan of the brain, which had revealed no abnormalities. He denied any other head and neck complaints, but reported an 11-kg weight loss over 3 months. His medical and social histories were significant for hypertension and 30 pack-years of smoking. He had been a carpenter and homebuilder for 20 years and more recently had been a produce shipper. He had continued to pursue carpentry as a hobby until the time of presentation. At admission, neurologic examination showed generalized confusion, but no localized findings. A magnetic resonance imaging scan of the brain revealed a mass in the right posterosuperior nasal cavity and anterior cranial fossa, with low to intermediate T2 and intermediate T1 signal intensities and homogeneous enhancement with gadolinium as well as ipsilateral opacification of the ethmoidal, maxillary, and frontal sinuses (Figure 1). Erosion of the floor of the anterior cranial fossa with contiguity with the nasal mass was suspected. Otolaryngologic consultation was requested for evaluation of the sinonasal mass. Rigid endoscopic examination of the right nasal cavity revealed a superiorly based pedunculated, friable mass medial to the middle turbinate, displacing the turbinate laterally. The findings of the rest of the head and neck examination were unremarkable. A biopsy specimen of the nasal mass showed papillary and tubular structures lined by crowded, pseudostratified columnar cells with hyperchromatic, pleomorphic nuclei with prominent nucleoli and frequent mitoses (Figure 2 and Figure 3). These glandular structures were irregular and complex and contained necrotic cellular debris, all in a background of chronically inflamed, fibrotic stroma.