# A Rare Case of Poorly Differentiated Lower Esophageal Cancer with Neuroendocrine Differentiation and α-Fetoprotein Production

## TL;DR

A rare case of esophageal cancer with both neuroendocrine features and α-fetoprotein production is reported, highlighting its unusual characteristics and treatment response.

## Contribution

This paper presents an extremely rare case of esophageal carcinoma with neuroendocrine differentiation and α-fetoprotein production, expanding the known clinical spectrum of such tumors.

## Key findings

- The tumor exhibited poorly differentiated carcinoma with neuroendocrine and enteroblastic components.
- The patient achieved a complete response after chemotherapy and immune checkpoint inhibitors despite advanced metastasis.
- The coexistence of hepatoid adenocarcinoma and neuroendocrine features is linked to poor prognosis in esophageal cancer.

## Abstract

Neuroendocrine differentiation and α-fetoprotein production (AFP) are 2 rarely reported features in poorly differentiated gastric carcinomas. We report an extremely rare case of esophageal carcinoma (EC) featuring both histologic types.

A 67-year-old man was referred to our hospital with dysphagia and weight loss. Upper gastrointestinal endoscopy revealed a type 3 tumor in the lower esophagus, 32–40 cm from the incisors, with luminal stenosis. The endoscopic biopsy specimen showed pathologic features of poorly differentiated carcinoma, and immunostaining revealed findings consistent with neuroendocrine carcinoma (NEC). CT showed no evidence of distant metastasis, although signs of metastatic lymph nodes were observed in the mediastinum and lesser curvature of the stomach. The patient declined chemotherapy and underwent thoracoscopic esophagectomy, which revealed advanced lymph node metastasis, particularly involving the left membranous trachea and pancreas. The resected tumor measured 90 × 80 mm and exhibited a type 3 pattern; the tumor center was located in the lower esophagus. Histologic examination of the resected specimen revealed Barrett’s esophagus (BE), with no continuity observed between the tumor and BE. The final diagnosis was poorly differentiated carcinoma with neuroendocrine and enteroblastic components. Despite extensive postoperative progression of lymph node metastasis revealed by CT, the patient achieved a complete response following the administration of chemotherapy and immune checkpoint inhibitors.

Accumulating evidence suggests that the coexistence of hepatoid adenocarcinoma and neuroendocrine differentiation is associated with poor prognosis in EC, and further studies are warranted to develop specific treatment criteria for adjuvant therapy in patients with EC harboring these features.