- Fever of unknown origin presents both a clinical and diagnostic challenge and is usually caused by inflammatory and neoplastic diseases. We present a unique case of a previously healthy 77-year-old woman whose sole complaint was fever. Complete hospital investigation failed to reveal the underlying process. 4 months after the onset of fever, dysphagia appeared and she was then diagnosed as suffering from squamous cell carcinoma of the esophagus. The question of early barium swallow X-ray in such cases is raised.