Gastroesophageal Junction Adenocarcinoma Presenting With De Novo Metastatic Disease and Ovarian Metastasis in a Young Woman With Atypical Chest Pain

A 33-year-old woman presented with progressive dysphagia and pleuritic chest pain, initially undergoing an unrevealing cardiopulmonary evaluation. Persistent symptoms prompted upper endoscopy, which demonstrated an ulcerated gastroesophageal junction lesion, with biopsy confirming invasive moderately to poorly differentiated adenocarcinoma. Immunohistochemical studies showed intact mismatch repair protein expression and negative human epidermal growth factor receptor 2 and Claudin 18.2, while programmed death-ligand 1 expression was markedly elevated (tumor proportion score 80%; combined positive score 80). Comprehensive next-generation sequencing revealed no actionable genomic alterations. Staging positron emission tomography demonstrated widespread metastatic disease, including involvement of the regional lymph nodes, liver, and ovary. The patient was treated with combination chemotherapy and immune checkpoint inhibition. This case highlights an atypical presentation of advanced gastroesophageal junction adenocarcinoma in a young adult and underscores the importance of early endoscopic evaluation in patients with persistent dysphagia, as well as recognition of uncommon metastatic patterns and the therapeutic implications of biomarker profiling.