A 30-year-old man presented with a 6-month history of depressed skin lesions on his back. On physical examination, numerous well-defined, erythematous, atrophic plaques were noted across the back. A fluorescence staining preparation of skin scrapings showed thick fungal hyphae and yeast cells with a “spaghetti and meatballs” pattern. What is the most likely causative organism for this skin infection?

1. Candida species

2. Epidermophyton species

3. Malassezia species

4. Microsporum species

5. Trichophyton species

Correct Answer: Malassezia species

• Left Image: Shows erythematous and atrophic plaques characteristic of Malassezia infection (Tinea Versicolor).

• Right Image: Fluorescence microscopy highlights the "spaghetti and meatballs" appearance diagnostic for Malassezia species.

1️⃣ Trigger Factors
🧠 Excess Sebum Production (lipid-rich areas)
🧠 Warm & Humid Environment
🧠 Immunosuppression or Altered Skin Microenvironment
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Overgrowth of Malassezia Species (normal skin commensal → pathogenic overgrowth)
⬇
2️⃣ Fungal Activity
🧠 Malassezia Produces Azelaic Acid & Lipase

Lipase: Breaks down sebum → Free fatty acids → Irritation

Azelaic Acid: Inhibits melanocyte activity → Hypopigmentation
⬇
3️⃣ Skin Changes

Localized Inflammation → Erythema (red patches)

Damage to Epidermis → Atrophic Plaques

Altered Melanin Production → Pigmentary Changes (hypo- or hyperpigmented lesions)
⬇
4️⃣ Diagnostic Features

"Spaghetti and Meatballs" Pattern on Microscopy: Hyphae + Yeast cells

Rash on seborrheic areas (trunk, back, chest)

Explanation of Other Answers

Candida species

• Candida typically causes mucosal infections, such as oral thrush or vulvovaginitis, or cutaneous infections in areas of moisture and occlusion. It does not produce the “spaghetti and meatballs” pattern seen in this case.

2. Epidermophyton species

• Epidermophyton is a dermatophyte that causes tinea infections of the skin, hair, and nails. It produces septate hyphae, not the “spaghetti and meatballs” pattern.

4. Microsporum species

• Microsporum is another dermatophyte that causes tinea infections, especially of the scalp and body. It does not produce the characteristic fungal appearance described here.

5. Trichophyton species

• Trichophyton, a dermatophyte, is a common cause of tinea infections, particularly of the scalp, body, and nails. Like other dermatophytes, it does not exhibit the "spaghetti and meatballs" pattern.

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