Disease
Dermatophytosis / ringworm
Annular scaly plaque with central clearing
der-mat-oh-fye-TOH-sis
High-yield clue
An itchy annular (ring-shaped) plaque with a raised scaly advancing border and central clearing is the classic ringworm clue.
Overview
A superficial fungal infection of keratinized skin, hair, and nails by dermatophytes, studied by body-site naming such as tinea corporis, capitis, pedis, and cruris.
Classification
- Superficial fungal (dermatophyte) syndrome
- Trichophyton / Microsporum / Epidermophyton
- Keratin-restricted
- Contagious by contact and fomites
Lab & identification clues
- KOH prep branching septate hyphae vocabulary
- Wood's lamp fluorescence (some Microsporum) vocabulary
- Named by body site: corporis / capitis / pedis / cruris
Associations
- Transmission: person-to-person, animals, and fomites (locker rooms)
- Tinea pedis ('athlete's foot') and tinea cruris ('jock itch')
- Tinea capitis with kerion in children
- Onychomycosis (nail) chronicity vocabulary
Commonly confused with
- Tinea versicolor (Malassezia)
- Nummular eczema
- Erythema migrans (Lyme)
Frequently asked questions
What is Dermatophytosis / ringworm?
A superficial fungal infection of keratinized skin, hair, and nails by dermatophytes, studied by body-site naming such as tinea corporis, capitis, pedis, and cruris.
What is the high-yield clue for Dermatophytosis / ringworm?
An itchy annular (ring-shaped) plaque with a raised scaly advancing border and central clearing is the classic ringworm clue.
What is Dermatophytosis / ringworm associated with?
Dermatophytosis / ringworm is associated with Transmission: person-to-person, animals, and fomites (locker rooms); Tinea pedis ('athlete's foot') and tinea cruris ('jock itch'); Tinea capitis with kerion in children; Onychomycosis (nail) chronicity vocabulary.
What is Dermatophytosis / ringworm commonly confused with?
Dermatophytosis / ringworm is commonly confused with Tinea versicolor (Malassezia), Nummular eczema, and Erythema migrans (Lyme).
Original student-study summary. Sources checked: OpenStax Microbiology 2e, NCBI Bookshelf Medical Microbiology, and CDC topic pages where applicable; reviewed 2026-06. Educational only; no diagnosis, treatment, dosing, or specimen-handling guidance.