A 24-year-old woman comes to the office due to skin lesions on her trunk and proximal upper limbs. The patient noticed the lesions after returning from a summer vacation at a Florida beach a week ago. During the vacation, she had sun exposure on several occasions without prior application of sunscreen. The lesions are mildly itchy but not painful. Medical history is notable for hypothyroidism, for which she takes levothyroxine. She drinks alcohol on social occasions but does not use tobacco or illicit drugs. Examination shows hypopigmented lesions as shown in the image below. Which of the following is the most likely cause of this patient's current condition?

Question

A 24-year-old woman comes to the office due to skin lesions on her trunk and proximal upper limbs.  The patient noticed the lesions after returning from a summer vacation at a Florida beach a week ago.  During the vacation, she had sun exposure on several occasions without prior application of sunscreen.  The lesions are mildly itchy but not painful.  Medical history is notable for hypothyroidism, for which she takes levothyroxine.  She drinks alcohol on social occasions but does not use tobacco or illicit drugs.  Examination shows hypopigmented lesions as shown in the image below.  Which of the following is the most likely cause of this patient's current condition?

Quizplus · Accepted Answer

11ec25c8_d391_8920_bc81_732c442acc71_MD0003_00 Tinea versicolor (pityriasis versicolor) is a superficial fungal skin infection caused by Malassezia species (nondermatophytic, lipid-dependent yeasts; eg, M globosa, M furfur). It is characterized by salmon-colored, hyper- or hypopigmented macules that are sometimes covered by fine scales, most commonly on the upper trunk and extremities. Hypopigmented areas are frequently noticed following sun exposure due to tanning of the surrounding skin. Lesions may be itchy. Potassium hydroxide (KOH) preparation of skin scrapings shows a "spaghetti and meatballs" appearance with large, blunt hyphae (spaghetti) and thick-walled budding yeast (meatballs). Topical treatment with selenium sulfide or ketoconazole is recommended, but the pigmentation changes can take months to resolve following treatment. budding yeast (Choice A) Vitiligo is characterized by complete depigmentation (from melanocyte destruction, possibly due to autoimmune mechanisms). However, it most commonly affects the face and hands and would not cause pruritus. Vitiligo (Choice B) Cutaneous candidiasis presents with an erythematous, vesiculopapular rash in warm, moist areas (eg, skinfolds). It is often associated with recent antibiotic use or immunocompromised states (eg, uncontrolled diabetes). Cutaneous candidiasis (Choice C) Irritant contact dermatitis is caused by physical or chemical irritation, most commonly due to soaps, solvents, or acid/alkali. It presents with erythema and fissuring, usually on the hands. (Choice D) Tinea corporis (ringworm) presents as annular lesions with advancing scaly borders and central clearing or as scaly patches over the trunk. Other dermatophyte infections include tinea pedis (athlete's foot), tinea cruris (jock itch), and tinea capitis (scalp ringworm). Tinea versicolor is the only tinea infection that is not caused by dermatophytes (which require keratin for growth). Tinea corporis (Choice E) Psoriasis is characterized by epidermal hyperproliferation and abnormal differentiation, and causes erythematous plaques over extensor surfaces. Guttate psoriasis presents with scattered, scaly, erythematous papules or small plaques, typically following an acute streptococcal infection. Guttate psoriasis (Choice G) Ultraviolet injury can lead to acute (eg, sunburn) or chronic (eg, photoaging) dermal injury. Sunburn may show patchy involvement due to uneven application of sunscreen, but round hypopigmented macules would be unusual. Educational objective: Tinea versicolor is a superficial nondermatophyte fungal skin infection caused by Malassezia species and characterized by salmon-colored, hyper- or hypopigmented macules. The diagnosis is confirmed with potassium hydroxide preparation of skin scrapings, and treatment is with topical antifungals. References: Pityriasis versicolor: an update on pharmacological treatment options. (http://www.ncbi.nlm.nih.gov/pubmed/24991691)

A 24-Year-Old Woman Comes to the Office Due to Skin