Candidiasis vs Tinea dermatophytes and pityriasis versicolor
How to tell Candidiasis and Tinea dermatophytes and pityriasis versicolor apart when a board question makes them look alike.
Candida = mucosal/moist yeast with pseudohyphae; dermatophyte = keratin ringworm hyphae; pityriasis versicolor = Malassezia pigment patches with spaghetti-and-meatballs.
Side by side
Candida causes thrush, vulvovaginitis, intertrigo, diaper rash, esophagitis in immunosuppression, and budding yeast with pseudohyphae on KOH.
Dermatophyte tinea causes annular scaly plaques, hair/nail/skin infection, and septate hyphae; pityriasis versicolor causes hypo/hyperpigmented trunk macules with Malassezia spaghetti-and-meatballs KOH.
Candida is an opportunistic yeast that overgrows on mucosa or moist skin and can invade in immunocompromised or catheterized hosts.
Dermatophytes digest keratin in stratum corneum, hair, or nails; Malassezia is lipophilic superficial yeast limited to stratum corneum.
Scrapable white oral plaques, satellite pustules, pseudohyphae/budding yeast, germ tubes, diabetes, antibiotics, pregnancy, or low CD4 support candidiasis.
Annular ringworm with central clearing supports dermatophyte; KOH spaghetti-and-meatballs, fine scale, and upper trunk pigment change support pityriasis versicolor.
The trap
Not every rash called tinea is a dermatophyte; tinea versicolor is Malassezia, not dermatophyte ringworm.
The repair move
For superficial fungal infection, match site, KOH pattern, and risk factor: (1) CANDIDA (Candida albicans is most common, dimorphic yeast that forms pseudohyphae and germ tubes at 37 degrees C) on MOIST MUCOSAL surfaces (oral thrush, esophagitis, vulvovaginitis, balanitis, diaper rash with satellite lesions, intertrigo); KOH shows budding yeast plus pseudohyphae; risk factors include diabetes, immunocompromise (HIV with CD4 below 200), broad-spectrum antibiotics, corticosteroids; treat with topical or oral azoles (fluconazole) or nystatin for oral. (2) DERMATOPHYTES (Trichophyton, Microsporum, Epidermophyton; keratin-loving molds): tinea pedis (athletes foot), tinea corporis (ringworm), tinea cruris (jock itch), tinea capitis (scalp with kerion), tinea unguium / onychomycosis; KOH shows septate hyphae with arthroconidia; treat topical for skin (terbinafine or azole), oral terbinafine or griseofulvin for scalp and nails. (3) PITYRIASIS VERSICOLOR (Malassezia furfur, a lipophilic yeast, NOT a dermatophyte despite the 'tinea versicolor' name): hyper- or hypopigmented patches on trunk and shoulders in young adults; KOH shows 'spaghetti-and-meatballs' pattern (short hyphae plus round yeast); treat with topical selenium sulfide, ketoconazole, or terbinafine.
Try a free question
CoreA patient with recent antibiotics has vulvar itching and thick discharge; KOH shows budding yeast with pseudohyphae. Which diagnosis is most likely?
Show answer and explanation
Answer: A. Candidiasis. Vulvovaginal symptoms with budding yeast and pseudohyphae support Candida.
Why the other choices are tempting
- B. Dermatophyte tinea corporis causes annular scaly skin plaques.
- C. Pityriasis versicolor causes pigment-changing trunk macules with Malassezia.
- D. Scabies causes intensely pruritic burrows.
- E. Erythrasma fluoresces coral-red from Corynebacterium.
Flashcards
Tap a card to flip it.
What KOH finding supports Candida?
Budding yeast with pseudohyphae supports Candida.
What oral finding supports candidiasis?
Scrapable white oral plaques support thrush from candidiasis.
Quick answers
What is the fastest way to tell Candidiasis from Tinea dermatophytes and pityriasis versicolor?
Candida = mucosal/moist yeast with pseudohyphae; dermatophyte = keratin ringworm hyphae; pityriasis versicolor = Malassezia pigment patches with spaghetti-and-meatballs.
What is the key clue for Candidiasis?
Candida causes thrush, vulvovaginitis, intertrigo, diaper rash, esophagitis in immunosuppression, and budding yeast with pseudohyphae on KOH.
What is the key clue for Tinea dermatophytes and pityriasis versicolor?
Dermatophyte tinea causes annular scaly plaques, hair/nail/skin infection, and septate hyphae; pityriasis versicolor causes hypo/hyperpigmented trunk macules with Malassezia spaghetti-and-meatballs KOH.
What is the common trap with Candidiasis vs Tinea dermatophytes and pityriasis versicolor?
Not every rash called tinea is a dermatophyte; tinea versicolor is Malassezia, not dermatophyte ringworm.