A Pseudoparasite of the Scalp Hair

In the past year, three cases were seen showing nodal attachments to the scalp hair which had been previously diagnosed and treated as "nits." On examination, 2.0 mm.-sized grayish bodies were seen encircling the hair shafts. These bodies were freely movable along the long axis of the hair. Although on casual inspection they appeared somewhat suggestive of nits, microscopic examination revealed significant differences. The body was tubular rather than pyriform, (Fig. 1) and showed a cellular structure. Under polarized light, it exhibited the birefringence characteristic of keratin. In cross section it showed considerable similarity to hair root sheaths seen in tissue sections (Fig. 2). It may be concluded that the bodies seen on the hair are root sheaths, extruded as casts from the follicle, and remaining on the hair shaft. In the clinical cases, from 1 to 300 such casts were seen. There was no associated disease of