RESUMO
Neuroendocrine carcinomas have been described in the larynx, lungs, middle ear and salivary glands. They represent a diverse spectrum of histological types with typical carcinoid at the benign end, atypical carcinoid in the middle, and small and large cell neuroendocrine carcinoma at full malignant. The purpose of this article is to describe and discuss the biologic behavior of a rare case of carcinoid tumour of the maxillary sinus. Many sinonasal neoplasms appear to be composed of small to medium sized cells that stain blue with conventional haematoxylin and eosin [H and E] stain. The category of round blue-cell tumour is quite large. Histological diagnosis using H and E alone pose a great challenge. The use of immunohistochemical or histochemical methods is an important tool that can be valuable in reaching the diagnosis as shown in the present case by grimelius histochemical method. In addition, the histological, radiological and clinical presentation of this tumour in the maxillary sinus denoted that the lesion had an aggressive biological behavior