Contributor: Gordon K. Klintworth
Neuroendocrine carcinoma is a malignant neuroendocrine tumor. It can be subdivided into large-cell neuroendocrine carcinoma [neuroendocrine carcinoma - large cell] and small-cell carcinoma [carcinoma - small cell], Merkel cell tumor and malignant carcinoid tumor [carcinoid tumor]. The carcinoid syndrome is almost invariably associated with midgut derived serotonin producing carcinoid tumor sthat have metastasized to the liver. A special type of neuroendocrine carcinoma is the olfactory neuroblastoma (esthesioneuroblastoma) that arises from neurons in the olfactory mucosa. Neuroendocrine carcinoma is a synonym for esthesioneuroblastoma and olfactory neuroblastoma. The tumor cells form lobules or sheets separated, by fibrovascular stroma. Occasionally Flexner-Wintersteiner rosettes and Homer Wright rosettes may be identified. The tumor cells contain argyrophilic neurosecretory granules. The esthesioneuroblastoma has a bimodal age distribution with peaks at 20 and 50 years. The tumor is slowly growing and may invade the orbit and intracranial cavity. Distant metastases occur in ~20% of cases. The differential diagnosis includes metastatic carcinoma and nasopharyngeal carcinoma [carcinoma - nasopharynx]. The tumor is radiosensitive. The small cell carcinoma of the lung is a neuroendocrine carcinoma that expresses L-histidine decarboxylase, CD56 and microtubules-associated protein-2.