Peripilar keratin casts: a study with the scanning electron microscope.

Two cases of Peripilar keratin casts are presented and the results of a Scanning EM investigation are discussed. The surface of the casts is very irregular and disordered. In the underlying structure of the casts the characteristic image of a "sponge" is observed. The cuticle of the hair beneath is slightly flaky, showing fissures. The hair surface facing the peripilar casts is normal.