Version June 2024
| Pediculosis (capitis or pubis) | Trichomycosis | White piedra | Black piedra | Hair casts | |
| Etiology | Parasite - Pediculosis humanus capitis, Phthirus pubis | Bacteria - Corynebacterium species* | Fungus - Trichosporon species | Fungus - Piedraia hortae | May represent persistent hair root sheaths; can occur in association with scalp disorders (eg, seborrheic dermatitis, psoriasis, traction alopecia) |
| Appearance | Translucent, gray-white, 0.5 to 1 mm, ovoid louse eggs (nits); adult or nymph lice; excoriations | Creamy, opaque, yellow-white¶, soft nodules and sheaths surrounding hair shaft; malodorous | Soft to firm, white to brown, 1 to 3 mm nodules | Firm, dark brown, 1 to 3 mm nodules | Whitish, tubular, 2 to 7 mm structures that encircle hair shafts |
| Mobility | Firmly adherent | Easily scraped off | May slide along hair shaft or remain adherent | Firmly adherent | Slide easily along hair shaft |
| Common sites | Scalp, pubic, perianal areas; occasionally axilla or other hairy sites | Axillary hair (most common), pubic hair, intergluteal hair | Scalp, facial, axillary, or pubic hair | Scalp, beard, axillary, or pubic hair | Scalp |
| Symptoms | Pruritus | None | None | None | Symptoms of associated scalp condition, if present |
| Other findings | N/A | KOH preparation - Opaque, sheath-like structures surrounding hair shaft Wood's lamp - Bright yellow-white or yellow-green fluorescence Gram stain - Gram-positive coccobacillary structures | KOH preparation - Spores and hyphae surrounding the hair shaft | KOH preparation - Spores and hyphae surrounding the hair shaft | N/A |
KOH: potassium hydroxide; N/A: not applicable.
* Dermabacter hominis has also been reported to cause trichomycosis.
¶ Occasionally, trichomycosis concretions are red or black.آیا می خواهید مدیلیب را به صفحه اصلی خود اضافه کنید؟
