Foamy Histiocyte-like Esophageal Adenocarcinoma: Unusual Morphology and Diagnostic Pitfalls

In the United States and other western countries, the vast majority of primary esophageal malignancies are adenocarcinomas arising in the lower esophagus within a background of Barrett's esophagus. The microscopic feature of esophageal adenocarcinoma varies, with the tubular or papillary adenocarcinoma of intestinal pattern being the most common, and other less common morphological patterns include adenosquamous, signet ring cell, mucinous, mucoepidermoid, and adenoid cystic carcinoma. This is a case report of esophageal adenocarcinoma with foamy histiocyte-like feature in a 71-year-old male with a history of smoking and Barrett's esophagus who presented with dysphagia and weight loss. The tumor cells showed an abundant foamy cytoplasm, low N/C ratio and irregular nuclear contour. They were arranged in single, trabecular and glandular patterns and deeply invaded adventitia. Lymphovascular invasion and perineural invasion were present. The foamy histiocyte like-tumor cells were negative for CD68, but strongly and diffusely positive for CK7. E-Cadherin was maintained in the tumor cells, and p53 immunostaining revealed a wild-type staining pattern. To the best of our knowledge, this is the first documented case of primary esophageal adenocarcinoma with foamy-histiocyte-like phenotype. The clinical course, diagnosis and prognosis of this entity are discussed.