Hair cast

From Biology-Online Dictionary | Biology-Online Dictionary

Hair cast

1. A cast composed of parakeratotic scales attached to scalp hair but freely movable up and down the hair shaft; found in scaling dermatitis of the scalp, including dandruff, psoriasis, and seborrheic dermatitis.

Synonym: pseudonit.

2. A small, nodular accretion of epithelial cells and keratinous debris resulting from failure of the internal root sheath to disintegrate; it appears for 3 to 7 mm along the hair shaft.