A patient presents with spaghetti and meatballs appearance on KOH preparation. What is the most likely diagnosis?

A patient presents with spaghetti and meatballs appearance on KOH preparation. What is the most likely diagnosis?

• A. Pityriasis versicolor
• B. Tinea capitis
• C. Seborrheic dermatitis
• D. Psoriasis

Answer: (A)

Spaghetti and meatballs on KOH prep point to Malassezia species thriving in the outer skin layer, producing a mixed appearance of short hyphae (spaghetti) and yeast cells (meatballs). This pattern is classic for pityriasis versicolor, a superficial fungal infection that causes patchy hypo- or hyperpigmented areas with fine scaling on the trunk and upper body, especially in hot, humid climates. In contrast, tinea capitis involves invasion of hair shafts and would show fungal elements within hairs rather than the characteristic spaghetti-meatball morphology. Seborrheic dermatitis can involve Malassezia as well but does not produce this distinctive KOH pattern, and psoriasis presents with well-demarcated plaques and negative KOH findings. Therefore, the most likely diagnosis is pityriasis versicolor.

Spaghetti and meatballs on KOH prep point to Malassezia species thriving in the outer skin layer, producing a mixed appearance of short hyphae (spaghetti) and yeast cells (meatballs). This pattern is classic for pityriasis versicolor, a superficial fungal infection that causes patchy hypo- or hyperpigmented areas with fine scaling on the trunk and upper body, especially in hot, humid climates.

In contrast, tinea capitis involves invasion of hair shafts and would show fungal elements within hairs rather than the characteristic spaghetti-meatball morphology. Seborrheic dermatitis can involve Malassezia as well but does not produce this distinctive KOH pattern, and psoriasis presents with well-demarcated plaques and negative KOH findings. Therefore, the most likely diagnosis is pityriasis versicolor.