Parasitologists and allergists have long been cognizant of small crystalline bodies which occur in the sputa of patients with bronchial asthma or in the dysenteric stools of those afflicted with various types of parasitic colitis. In asthma, the crystals may be absent immediately after collection of the specimen, but appear after the sputum has stood for a time.1 In cases of enteritis due to amebiasis or helminthiasis, such crystalline bodies may appear in abundance in the feces.
Charcot-Leyden crystals, first described by Charcot in 1854, have a characteristic appearance regardless of their anatomic source; they are long, colorless, pointed at either end, and hexagonal in cross section (Fig 1). They are invariably associated with eosinophilia, and, whereas they are most commonly present in bodily secretions, they may also be noted in tissue biopsies characterized by a heavy local accumulation of eosinophils, as will be pointed out in this report.
HOWARD GM. Charcot-Leyden Crystals in Ophthalmology. Arch Ophthalmol. 1965;74(3):357-359. doi:10.1001/archopht.1965.00970040359013