Superficial Mycoses and Tinea Versicolor

Superficial Mycoses

• Involve the outer layer of the skin or hair shafts
• Don't invade living tissue or elicit a cellular response
• Often asymptomatic and go unnoticed

Tinea Versicolor

• Caused by Malassezia furfur
• Characterized by patchy, discolored skin lesions
• Commonly known as "an-an"
• Lesions occur on smooth skin, most commonly on the face, chest, arms, and abdomen
• Lesions can be hyper- or hypopigmented
• Appear dry and chalky due to scaling
• Common in hot, humid, tropical climates
• Prevalent in corticosteroid therapy patients

Tinea Versicolor: Lab Diagnosis

• Microscopic examination of KOH-treated skin scrapings reveals budding yeasts and septate hyphae
• "Spaghetti and Meatball" appearance
• Requires lipids for growth in culture
• Colonies are cream-colored, moist, and smooth, fluoresce yellow under Wood's lamp

Tinea Versicolor: Treatment

• Aims to eliminate the organism from the skin
• Topical miconazole nitrate is effective
• Anti-dandruff shampoos can be used

Tinea Nigra

• Caused by Hortaea werneckii
• Presents with brown to black, nonscaly macules, mostly on palms and soles
• Characterized by dematiaceous growth of yeast and hyphae

Tinea Nigra: Lab Diagnosis

• Direct examination of KOH-treated skin scrapings reveals septate hyphae and budding cells
• Younger cultures exhibit budding blastoconidia, older cultures show hyphae with clustered blastoconidia
• Produces shiny, moist, yeast-like colonies that start brown and turn olive to greenish black on SDA

Tinea Nigra: Treatment

• Responds to keratolytics
• Daily application of Whitfield's ointment
• Tincture of iodine, 2% salicylic acid, or 3% sulfur can also be used

White Piedra

• Caused by Trichosporon spp. (T. ovoides, T. asteroides, T. cutaneum, T. inkin, T. asahaii)
• Characterized by soft, cream-colored mycelial mats around hair on the scalp, face, and pubic region
• Primarily affects hairs of the scalp, axillae, genitals, and facial hair like mustaches and beards

White Piedra: Lab Diagnosis

• Trichosporon spp. grow rapidly on primary fungal media, producing arthroconidia, hyphae, and blastoconidia
• Colonies are straw to cream-colored and yeast-like
• Vary in appearance, smooth or wrinkled, dry or moist, creamy or velvety

White Piedra: Treatment

• Shaving or cutting infected hair is often sufficient
• Topical fungicides like bichloride of mercury (1:200)
• Benzoic and salicylic acid combinations
• 3% sulfur ointments
• 2% formalin can be used

Black Piedra

• Caused by Piedraia hortae
• Occurs on hair of the scalp
• Characterized by hard, dark brown to black, gritty nodules firmly attached to the hair shaft
• Differentiate from nits of pediculosis and abnormal hair growth

Black Piedra: Lab Diagnosis

• Infected hairs placed in KOH reveal asci when nodules are crushed
• Thick-walled rhomboid cells containing ascospores are observed
• Grows slowly on Sabouraud dextrose agar at room temperature, forming brown, restricted colonies

Black Piedra: Treatment

• Shaving or cutting infected hair is often sufficient
• Topical fungicides like bichloride of mercury
• Benzoic acid/salicylic acid combinations