Neuroendocrine carcinoma of the esophagus: a case report with immunohistochemical and molecular genetic analyses of KIT and PDGFRA

Neuroendocrine carcinoma of the esophagus including small-cell carcinoma and large-cell carcinoma is a very rare entity. The author herein reports a neuroendocrine carcinoma of the esophagus with an emphasis on KIT and PDGFRA. An 81-year-old man presented as dysphagia. An endoscopic examination revealed an ulcerated large tumor in the middle esophagus. A biopsy of the esophageal tumor identified an undifferentiated carcinoma consisting of malignant cells with hyperchromatic nuclei without differentiations. An immunohistochemical study revealed that the tumor cells were positive for cytokeratins, neuron-specific enolase, synaptophysin, p53 protein, KIT, and platelet-derived growth factor receptor-α (PDGFRA). The Ki-67 labeling was 100%. A pathologic diagnosis of neuroendocrine carcinoma with expression of KIT and PDGFRA was made. A genetic analysis using PCR direct sequencing method identified no mutations of KIT (exons 9, 11, 13, and 17) and PDGFRA (exons 12 and 18) genes. The patient underwent radiation and cisplatin-based chemotherapy. However, he developed systemic metastases and died of respiratory failure 8 months after the first manifestation. The present case is the first one of esophageal neuroendocrine carcinoma with an examination of protein expressions and gene mutations of KIT and PDGFRA.