Hair Casts (syn: peripilar keratin casts)
Hair Casts present as non-adherent white or yellowish cylindrical collarettes with a length of 1-6 mm that encircle a hair-shaft and can freely slide along its length.
They present in small or large numbers at any scalp location.
Cross sectional microscopical examination reveals a central region of root-sheath cells surrounded by keratinised cells.
Hair casts may or may also not be associated with Pityriasis conditions (Pityriasis is a genus of non-pathogenic yeast-like fungi which produce fine spores but no mycelium). Pityriasis proliferates in ‘Dandruff ‘ and ‘Seborrhoeic Dermatitis’ and ‘Pityriasis Amiantacea’ and ‘Psoriasis of the scalp’.
Young females are at greatest risk of demonstrating hair casts.
Static hair casts may be confused with:
• White Piedra (a stone) – due to trichosporum cutaneum ( syn trichosporum beigelii ) – a yeast-like fungus which surrounds the hair-shaft and may eventually invade the cortex causing severance (trichorrhexis nodosa).
• Trichorrhexis Nodosa
• Pediculus Capitis
• Seborrheic Dermatitis
• Trichomycosis Nodosa.
Macroscopical or microscopical examination together with the will differentiate hair casts from the other possibilities.
Treatment: Soak the hair casts in acetic acid and comb them off the shaft at the distal end.
A Case Example
A Caucasoid female (23 years) presented with numerous hair-shafts bearing white accretions resembling the ova of pediculosis capitis. Pruritis was absent. Visual examination failed to locate parasites.
Diagnosis: confirmed through physical examination which revealed that the white collarettes could slide along the hair-shafts.
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