From presumed metastasis to infection: coccidioidomycosis mimicking metastatic gastroesophageal adenocarcinoma

Early gastroesophageal junction (GEJ) cancer commonly presents without distant disease. The development of locoregional lymphadenopathy and acute pulmonary embolism raises concern for metastatic disease and may lead to inappropriate upstaging if not properly investigated. We present a 51-year-old immunocompetent Hispanic man with newly diagnosed T1a GEJ adenocarcinoma who developed FDG-avid mediastinal lymphadenopathy and an incidental subsegmental pulmonary embolism on staging computed tomography. Histological sampling via endobronchial ultrasound-guided fine needle aspiration revealed granulomatous inflammation without malignancy. Further workup confirmed an acute Coccidioides lymphadenitis. The patient was successfully treated with fluconazole 400 mg daily for three months, with complete radiological and endoscopic resolution. This case underscores the critical importance of histological confirmation of lymphadenopathy before attributing it to metastatic disease in early-stage GEJ cancer. Failure to consider infectious etiologies, particularly coccidioidomycosis in endemic areas or in patients with travel history, may result in unnecessary upstaging, inappropriate treatment escalation, and avoidable harm.