Isolated Primary Sinonasal Adenocarcinoma of the Sphenoid Sinus.

Isolated lesions of the sphenoid sinus, particularly malignancies, are rarely reported and exist largely within the Otolaryngology literature. Delayed diagnosis may necessitate neurosurgical involvement; therefore, neurosurgeons must be aware of the range of pathologies in this region in order to provide adequate treatment. We present an unusual case of an 89-year-old female with several weeks of worsening headaches, vision loss, and cranial neuropathies. Work-up at an outside hospital was non-diagnostic. After referral, an expansive and erosive lesion within the left sphenoid sinus was identified. A transsphenoidal approach for resection of the lesion yielded a primary non-salivary non-intestinal type sinonasal adenocarcinoma, as well as bacterial sinusitis and probable allergic fungal sinusitis. The patient was treated with antimicrobial medications as well as stereotactic radiosurgery. Her neurological deficits did not improve with treatment, and she ultimately expired 3.5 months post-operatively after transition to hospice. Primary sinonasal adenocarcinoma is a very rare pathology in this location. Surgical intervention is necessary to obtain an accurate diagnosis and proceed with appropriate treatment. Delayed diagnosis likely portends a worse prognosis.