Which finding on a KOH skin scraping supports a diagnosis of tinea capitis?

Which finding on a KOH skin scraping supports a diagnosis of tinea capitis?

• A. Yeast budding and pseudohyphae
• B. Septate and branching, long, narrow hyphae
• C. Gram-positive cocci in clusters
• D. Acanthamoeba cysts

Answer: (B)

Tinea capitis is a scalp infection caused by dermatophyte fungi, and a KOH prep helps visualize fungal elements by dissolving keratin so the filaments stand out. The hallmark finding is long, slender hyaline hyphae that are septate and branch at acute angles. This pattern reflects the characteristic filaments of dermatophytes invading hair and skin. Other options describe different organisms or processes: yeast budding and pseudohyphae point to yeast infections like Candida or Malassezia; Gram-positive cocci in clusters suggest bacterial folliculitis; Acanthamoeba cysts indicate an amoebic infection. Thus, septate, branching hyphae on KOH best supports tinea capitis.

Tinea capitis is a scalp infection caused by dermatophyte fungi, and a KOH prep helps visualize fungal elements by dissolving keratin so the filaments stand out. The hallmark finding is long, slender hyaline hyphae that are septate and branch at acute angles. This pattern reflects the characteristic filaments of dermatophytes invading hair and skin.

Other options describe different organisms or processes: yeast budding and pseudohyphae point to yeast infections like Candida or Malassezia; Gram-positive cocci in clusters suggest bacterial folliculitis; Acanthamoeba cysts indicate an amoebic infection. Thus, septate, branching hyphae on KOH best supports tinea capitis.