S2136 Serendipitous Surveillance: A Case of Alpha-Fetoprotein-Producing Esophageal Adenocarcinoma in a Patient With Prior Seminoma

Introduction: Alpha-fetoprotein (AFP)-producing esophageal adenocarcinoma (EAC) is a rare diagnosis. High AFP levels in adults are typically associated with primary hepatocellular carcinoma or yolk sac tumors. Here we report an interesting case of an AFP-producing EAC found in an asymptomatic patient with history of a germ cell tumor. Case Description/Methods: A 67-year-old man with history of testicular seminoma status post orchiectomy and radiation 15 years ago underwent serum tumor marker surveillance and was incidentally found to have elevated AFP to 154 ng/ml (normal < 8.0 ng/mL). He was asymptomatic, not obese, and had no toxic habits. Basic bloodwork and imaging studies were unrevealing. Positron emission tomography-computed tomography (PET-CT) showed abnormal uptake at the gastroesophageal junction (GEJ) with hypermetabolic GEJ lymph nodes. Upper endoscopy (EGD) showed a GEJ circumferential mass from 38-42cm (Figure 1a), confirmed on subsequent endoscopic ultrasound (EUS) (Figure 1b). Biopsies revealed high-grade esophageal adenocarcinoma (Figure 1c-d) with loss of MLH1 and PMS2 staining (Figure 1e-f). He was started on neoadjuvant chemoradiation with improvement in AFP. Discussion: There are few case reports of AFP-producing EAC, which typically arise from Barrett’s metaplasia. Due to insidious early symptoms, dearth of screening techniques, and high malignant potential, AFP-producing tumors are often diagnosed at advanced stage with poor prognosis and poor response to chemotherapy.1 Our patient’s diagnosis was incidental, with no Barrett's or liver disease; EAC is an uncommon secondary cancer following seminoma, and seminoma do not typically express AFP.2 However, loss of MLH1 and PMS2 expression on histopathology suggests predisposing mismatch repair deficiency. It is unclear if EAC has a yet-unidentified association with germ cell tumors, and more studies are needed to identify at-risk populations to inform screening recommendations. When EAC is treated, AFP levels may be useful for monitoring for response and recurrence.3Figure 1.: a) Ulcerated, non-obstructing and partially circumferential mass seen at GE junction on EGD. b) Irregular border of ulcerated malignant esophageal tumor (hypoechoic, between green markers) seen above the GE junction at 39cm, along the lesser curve of the gastric cardia on EUS. c) Distal esophagus biopsies show high grade adenocarcinoma with poorly differentiated tumor that undermines the squamous epithelium of the esophagus. d) Areas of focal gland formation (yellow arrow) are consistent with adenocarcinoma gastroesophageal tumor, less consistent with seminoma or yolk sac tumor morphology. e-f) Tumor shows loss of MLH1 and PM2 expression, suggestive of microsatellite instability and predisposing mismatch repair deficiency.

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