Neuroendocrine Carcinoma and Sinonasal Undifferentiated Carcinoma.

Sinonasal malignancies are uncommon, representing 1% of all neoplasms. A wide spectrum of malignant neoplasms arise from the sinonasal and skull base regions; the majority of these tumors are poorly or undifferentiated tumors manifesting overlapping features that result in diagnostic challenges. Sinonasal neuroendocrine carcinoma (SNEC) and sinonasal undifferentiated carcinoma (SNUC) are types of sinonasal neuroendocrine tumor, together with olfactory neuroblastoma. They share overlapping clinical, radiological, and histopathological features, albeit with variability in behavior and prognosis between each other. The literature is at variance regarding the appropriate management strategy of these tumors due to their rarity and difficulty in establishing the correct diagnosis. In recent years progress has been made in the diagnostic techniques and treatment strategies implemented for these tumors. Here we provide a comprehensive review of the recent literature, focusing on the recent advances in histopathological and ancillary diagnosis, and different treatment options for SNEC and SNUC.