A Rare Case Report of Low-Grade Neuroendocrine Carcinoma Masquerading as Chronic Rhinosinusitis

A BSTRACT Neuroendocrine tumors are uncommon and diverse malignancies that exhibit varying histological characteristics and clinical manifestations. To differentiate between various histological types, an immunohistochemical examination must be performed, which requires a high level of skill from a diagnostic standpoint. Since these neoplasms are extremely rare, there are no established therapy approaches supported by evidence and prospective clinical studies are not available. Histopathology remains the gold standard along with clinical features and imaging studies which can facilitate an accurate diagnosis. Immunohistochemistry (IHC) also plays an important role in the diagnosis of these tumors. In our case, Ki-67, CD-56, chromogranin, and synaptophysin were performed which turned out to be positive hence supporting the diagnosis of neuroendocrine tumors. In our case, Ki67 index was low hence the diagnosis of low-grade neuroendocrine tumor was rendered. Identification of these cases becomes important as treatment outcomes and prognostication become easier. In this article, we are discussing a case that presented to us as chronic rhinosinusitis but on histopathological evaluation and IHC studies turned out to be a low-grade neuroendocrine tumor.