A Red Flag

A CLINICAL PROBLEM-SOLVING article by Reza Fazel from Emory University, Atlanta, Georgia.
A 64-year-old man was brought to the emergency department because of sudden-onset blurred vision in both eyes and diplopia, as well as a frontal headache that had begun earlier that day. On presentation, he was noted to have an altered mental status. His visual symptoms spontaneously resolved shortly after his arrival at the emergency department.
On physical examination, the patient was lethargic, was oriented to person and place but not to time, and had difficulty with word finding.
The hemoglobin level was 11.8 g per deciliter; the platelet count 234,000 per cubic millimeter, and the white-cell count 10,300 per cubic millimeter with  59% eosinophils.
Chest radiography revealed bilateral apical opacities.
This illness is distinguished by its multisystem involvement and the marked eosinophilia.
Complicated cases with multisystem manifestations often force clinicians to consider numerous diagnostic possibilities that span the major categories of disease, including infections, cancer, autoimmune disorders, and metabolic derangements. On occasion, the initial evaluation reveals a distinctive finding, or clinical red flag, that allows the clinician to transform a broad question (What is causing this multisystem illness?) into a more circumscribed problem (What explains this marked eosinophilia?).