Neuroendocrine tumor G1 in sphenoid sinuses: A case report.

Neuroendocrine neoplasms (NENs) commonly arise in the gastrointestinal tract, pancreas or lungs. Among NENs, there have been some reports of neuroendocrine carcinoma (NEC) occurring in the paranasal sinuses, but neuroendocrine tumors (NETs) of the paranasal sinuses are particularly uncommon, with only a few cases report available. Furthermore, there have been no comprehensive reports focusing on imaging findings. We herein report a case of paranasal sinus NET G1, along with a literature review of the imaging characteristics. The patient was a 64-year-old woman who was asymptomatic and had been incidentally diagnosed with a sphenoid sinus tumor. Computed tomography (CT) and magnetic resonance imaging (MRI) revealed a mass in the sphenoid sinus with heterogeneous contrast enhancement and destruction of the surrounding bones, including the sphenoid bone, clivus, and petrous bone. The mass had invaded the sella turcica and pushed the pituitary gland upward. The average and minimum apparent diffusion coefficient (ADC) values were 0.796 and 0.601 (× 10 mm/s), respectively. A tumor biopsy was performed, leading to the diagnosis of NET G1. Surgical resection was deemed unfeasible, and the patient was treated with radiation therapy. No tumor progression or recurrence was observed over the follow-up period of 10 years. Previous studies of gastrointestinal NETs have reported an association between ADC values and tumor differentiation. This suggests that ADC values may be useful for predicting the tumor grade in paranasal sinus NETs.