[A rare case of a neuroendocrine carcinoma of the esophagus. Intermediate between a well-differentiated neuroendocrine carcinoma and a low-differentiated neuroendocrine carcinoma].

We report a rare case of a neuroendocrine carcinoma located in the esophagus of a 62-year-old male patient. The initial diagnosis of a "small-cell tumor" was based on biopsy. Our diagnosis was based on the histomorphological examination of the resected material. Diagnostic criteria were the characteristic solid or clustered growth patterns, monomorphic cell nuclei, lack of necrosis, immunohistochemical detection of neuroendocrine markers like chromogranin, synaptophysin and neuron-specific enolase (NSE) as well as detection of cytoplasmic neuroendocrine granules by electron microscopy. In addition, we found an increased prolific activity by staining with Ki67 antigen. 30% of the cell nuclei displayed a positive reaction. Focal invasion of blood vessels was also detected. With 17 different chromosomal imbalances, comparative genomic hybridization (CGH) revealed a malignant tumor stage that was not visible at the microscopic level. According to the new WHO classification of neuroendocrine tumors the described tumor was identified as an intermediate between a well-differentiated neuroendocrine carcinoma and a low-differentiated neuroendocrine carcinoma.