Clinical Rarity Unveiled: Adenocarcinoma with Enteroblastic Differentiation at the Gastroesophageal Junction in a Young Patient - A Diagnostic Challenge Shaping Therapeutic Paradigms

Abstract Introduction/Objective This report details a case of a young patient diagnosed with an adenocarcinoma with enteroblastic differentiation at the gastroesophageal junction (GEJ), characterized by Alpha-Fetoprotein (AFP) production. This manifestation previously rarely documented in young patients (25-44 years old), underscores the critical role of precise pathology diagnosis in guiding effective patient management. Methods/Case Report The patient’s clinical presentation included chest pain, abdominal pain, and weight loss, prompting imaging studies revealing liver masses, lesions in the lung and adrenal gland, and retroperitoneal adenopathy with unremarkable testicular findings. Rapidly progressing dysphagia led to a liver biopsy and esophagogastroduodenoscopy (EGD), where a fungating mass extending from the distal esophagus into the stomach was biopsied. A subsequent serologic test unveiled an elevated serum AFP level (approximally 31, 000 ng/ml). Results (if a Case Study enter NA) Histological examination revealed similarities between the liver and distal esophageal tumors, characterized by moderately differentiated carcinoma with solid and glandular growth patterns. The tumor cells, resembling fetal gut epithelium, exhibited positive immunostaining for SALL4, AFP, CK8-18, CK19, and CDX2. A diagnosis of adenocarcinoma with enteroblastic differentiation at the GEJ was determined, correlating with clinical and radiological assessments. Despite initiating one cycle of gastrointestinal related chemotherapy, the patient succumbed to tumor lysis syndrome within a month of diagnosis. Conclusion This case highlights the critical need for a comprehensive differential diagnosis when encountering young patients with AFP-producing malignancies. Although metastatic non-seminomatous germ cell cancer is a primary consideration, upper gastrointestinal adenocarcinoma with unique characteristics, as demonstrated in this case, requires distinct therapeutic approaches, emphasizing the importance of accurate and timely diagnosis.