Esophageal adenosquamous carcinoma with mucinous carcinoma-predominant lymph node metastases: a case report.

BACKGROUND: Esophageal adenosquamous carcinoma is a rare histological subtype of esophageal cancer characterized by the coexistence of squamous cell carcinoma and adenocarcinoma components. Preoperative diagnosis is challenging because biopsy specimens often contain only the squamous component. CASE PRESENTATION: A 75-year-old man presented with dysphagia. Esophagogastroduodenoscopy revealed a type 3 tumor in the middle thoracic esophagus. Histopathological examination of the biopsy specimens demonstrated predominantly squamous cell carcinoma with a minor mucin-producing adenocarcinoma component, raising suspicion of adenosquamous carcinoma. Given the patient's history of myocardial infarction and poor cardiac function, neoadjuvant chemotherapy was considered unsuitable. The patient underwent thoracoscopic esophagectomy with lymph node dissection. Pathological examination confirmed adenosquamous carcinoma, with the superficial portion composed predominantly of moderately differentiated squamous cell carcinoma, whereas the deeper layers contained mucinous carcinoma and signet-ring cells. Extensive lymph node metastases were identified in the cervical, thoracic, and abdominal regions, the majority of which predominantly comprised mucinous carcinoma. At seven months postoperatively, mediastinal lymph node recurrence was detected. Due to the patient's deteriorating general condition, systemic chemotherapy was contraindicated, and the patient died 11 months postoperatively. CONCLUSIONS: We report a rare case of esophageal adenosquamous carcinoma with mucinous carcinoma-predominant lymph node metastases. The predominance of mucinous carcinoma in metastatic lesions may reflect the aggressive biological behavior of the adenocarcinoma component and could be associated with poor clinical outcomes. Although esophageal adenosquamous carcinoma is generally managed using surgery-based multidisciplinary strategies based on the treatment principles for esophageal squamous cell carcinoma, no standard chemotherapy regimen has been established for esophageal adenosquamous carcinoma. Further accumulation of cases is needed to determine the optimal treatment strategies for this rare disease.