Case Presentation: An 80-year-old female presented with several months of progressive dysphagia and weight loss. On physical exam she had diffuse cervical lymphadenopathy. Computed tomography (CT) of her neck revealed a 3.0 x 1.8-centimeter mass originating from the upper third of the esophagus and cervical LAD. Core needle biopsy of a cervical lymph node revealed malignant mucin secreting glands, and immunological staining was consistent with a moderately differentiated adenocarcinoma. Upper endoscopy and biopsy of the esophageal mass revealed glandular epithelium and columnar dysplasia, and flow cytometry was consistent with a moderately differentiated adenocarcinoma. Further immunohistochemical staining pointed away from lung or breast cancer, and histological studies were not consistent with intestinal metaplasia or gastric tissue. Initial positron emission tomography (PET) imaging revealed increased uptake in only the esophagus and surrounding lymph nodes. The patient was diagnosed with an adenocarcinoma of unknown primary and was treated with folinic acid, fluorouracil, and oxaliplatin (FOLFOX). Repeat radiographic staging before cycle 4 demonstrated interval improvements. Six months after her initial presentation, the patient was admitted for urosepsis. CT of the abdomen and pelvis revealed a 1.8 cm pancreatic body mass. Endoscopic ultrasound guided biopsy of this mass was consistent with pancreatic adenocarcinoma. The patient’s CA-19-9 was over 10,000 which is suggestive of a gastrointestinal source of her primary adenocarcinoma. The patient continued to decline developing hypoxemic respiratory failure and ultimately opted for hospice measures.
Discussion: Classically squamous cell carcinomas develop in the upper portion of the esophagus while adenocarcinomas develop in the lower portion of the esophagus. In some rare cases, adenocarcinomas of the upper esophagus have been described. These cases can be due to pre-existing congenital ectopic gastric mucosa but consideration also has to given to metastatic disease[1]. The most common primary cancers that give rise to upper esophageal metastasis are from the lung or breasts but usually the primary lesion is readily evident with these cancers[2]. Pancreatic cancer is relatively unusual in that it can metastasizes prior to the development of a primary mass. Along with the dissemination to rare sites like the upper esophagus, this ability highlights the profound metastatic potential of pancreatic adenocarcinomas.
Conclusions: Adenocarcinoma diagnosed in the upper esophagus should prompt clinicians to conduct a thorough staging assessment for a primary lesion if pathologic evidence of ectopic gastric tissue is absent. This case highlights the importance of close clinical follow up and frequent staging during treatment of adenocarcinomas of unknown primary. Early assessment with CA-19-9 in the setting of an unknown primary may offer a diagnostic benefit to further elucidate the primary etiology if it is not known.