Skin nontumor

• Numerous scattered and often coalescing macules, patches and thin plaques that may be pink, hypopigmented or hyperpigmented and can be mildly pruritic
• Fine scale can often be elicited by gently scraping the surface
• Atrophying tinea versicolor, an uncommon variant, presents with depressed or atrophic hypo or hyperpigmented macules and patches (Int J Dermatol 2003;42:928)

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• Direct microscopy of lesional scale prepared with KOH or chlorazol black shows clusters of budding ovoid yeasts (blastoconidia) and hyphae (pseudomycelium) referred to as spaghetti and meatballs (Lancet 2004;364:1173)
• H&E of skin biopsy shows ovoid budding yeasts and hyphae (spaghetti and meatballs) within the stratum corneum (Lancet 2004;364:1173)
• Fungi are accentuated with periodic acid-Schiff (PAS) or Gomori methenamine silver (GMS) stains (Lancet 2004;364:1173)
• Other histologic changes are often subtle or absent; slight hyperkeratosis or sparse superficial perivascular inflammatory infiltrate may be present (Patterson: Weedon’s Skin Pathology, 5th Edition, 2020)
• Atrophying tinea versicolor may have dermal elastolysis visible with Verhoeff van Gieson staining (Int J Dermatol 2003;42:928)

Contributed by Alexander J. Pybus, M.D. and C. Lamar Hardy, M.D.

What is the correct diagnosis for the image shown above?

1. Atopic dermatitis
2. Seborrheic dermatitis
3. Tinea versicolor
4. Vitiligo

C. Tinea versicolor. The patient shown has scattered and coalescing hypopigmented macules and scaly patches on the back, clinically consistent with tinea versicolor. This is a benign superficial skin infection with Malassezia species dimorphic fungi, which normally colonize the skin and convert into pathogenic mycelial forms in the presence of certain host skin factors. Answer A is incorrect because atopic dermatitis most commonly presents as xerotic or lichenified scaly papules and plaques in flexural skin areas, such as the neck, antecubital fossae and popliteal fossae. Answer B is incorrect because seborrheic dermatitis tends to present as dandruff on the scalp or erythematous papules and plaques on the central face, brows, nose and upper chest with overlying greasy appearing scale. Answer D is incorrect because vitiligo would present as depigmented macules and patches of skin without any associated scale.

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Reference: Tinea versicolor

What is the most appropriate first line treatment for the skin condition shown in the image above?

1. Amphotericin B
2. Clotrimazole
3. Oral griseofulvin
4. Oral terbinafine

B. Clotrimazole. This photomicrograph depicts ovoid budding yeasts and hyphae within the stratum corneum consistent with a diagnosis of tinea versicolor. The first line treatments for tinea versicolor are topical imidazole antifungals, such as clotrimazole or ketoconazole. Answer D is incorrect because oral terbinafine is a second line treatment to be reserved for patients who have not responded to topical therapy. Answers A and C are incorrect because amphotericin B and oral griseofulvin are not used to treat tinea versicolor.

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Reference: Tinea versicolor

What is the causative organism of the skin condition shown in the image above?

1. Aspergillus fumigatus
2. Coccidioides immitis
3. Cryptococcus neoformans
4. Malassezia globosa

D. Malassezia globosa. This photomicrograph shows ovoid budding yeasts and hyphae within the stratum corneum consistent with a diagnosis of tinea versicolor. This condition is caused by dimorphic lipophilic yeasts of the genus Malassezia (formerly known as Pityrosporum), specifically M. globosa, M. furfur and M. sympodialis. Answer A is incorrect because Aspergillus fumigatus causes aspergillosis, which in the skin would present as 3 - 6 µm septate hyphae with right angle branching in the dermis or with angioinvasion of dermal blood vessels. Answer B is incorrect because Coccidioides immitis can be seen cutaneously in disseminated coccidioidomycosis as thick walled spherules 10 - 80 µm in diameter within giant cells and granulomas in the dermis. Answer C is incorrect because Cryptococcus neoformans causes cryptococcosis, with 10 - 15% of cases presenting with cutaneous involvement, including disseminated involvement in immunocompromised patients, such as AIDS patients or organ transplant recipients. Histology of cryptococcosis would show dermal chronic inflammatory infiltrate with tuberculoid granulomas with few encapsulated yeast organisms 5 - 15 µm or even large mucoid masses of encapsulated organisms in some cases.

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Reference: Tinea versicolor