A 9-year-old girl is evaluated because of a rash. Multiple light patches appeared on the patient's face, chest, back, and arms a week after she began attending a swim camp and became more pronounced over the past month. The spots are mildly itchy but not painful. No dietary changes or use of new soaps has occurred. The patient applies a new suntan lotion 5 days a week while swimming in the camp's chlorinated pool; however, the spots do not tan even though the surrounding skin does. She has a history of allergic rhinitis and takes oral antihistamines. She has no history of major illness or hospitalization. Vital signs are normal. On examination, the patient is awake, alert, and comfortable. There is mild nasal congestion with enlarged turbinates and clear postnasal drip but no pharyngeal erythema. Lung sounds are clear. No heart murmurs are present. Multiple pale macules appear on the face, trunk, back, and upper arms, as shown in the image below.
Show Explanatory Sources
Some of the spots have slight scaling, and they are not tender to palpation. Which of the following is the most likely diagnosis in this patient?
Tinea versicolor (pityriasis versicolor) | |
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KOH = potassium hydroxide. | |
Tinea versicolor is a fungal infection of the skin usually caused by species of the yeast Malassezia. It typically manifests as flat, hyper- or hypopigmented skin lesions. Scaling and itching are variably present. Lesions generally involve the trunk and upper extremities, although facial involvement is common in children. The condition may first be noticed after sun exposure, when the surrounding skin becomes more darkly pigmented than the affected area. Diagnosis is usually made clinically, although a potassium hydroxide preparation demonstrates yeast cells and hyphae ("spaghetti and meatballs"). Topical therapy (eg, selenium sulfide, antifungals) generally results in resolution, although infection may recur.
(Choice A) Atopic dermatitis is common in children with seasonal allergies; however, the rash is typically erythematous, dry, scaly, and intensely pruritic. It usually appears on flexor surfaces and is not hypopigmented at initial presentation.
(Choice B) Irritant contact dermatitis might occur in a child using new skin products and swimming in a chlorinated pool. However, the rash is typically erythematous due to inflammation and may progress to dry, cracked skin. Discomfort and burning are common.
(Choice C) Mycosis fungoides, a hypopigmented rash that typically appears on the trunk, may be an initial presentation of cutaneous T-cell lymphoma. Severe pruritus is common. The presentation is less acute, and lesions relapse and remit over time regardless of season or sun exposure.
(Choice D) Pityriasis rosea classically begins with a single salmon-colored macule (herald patch) followed by the development of multiple lesions on the trunk and extremities, often in a "Christmas-tree" distribution. Lesions are erythematous and eventually desquamate, causing itching. It does not present as multiple hypopigmented spots.
(Choice E) Seborrheic dermatitis is commonly seen on the face, scalp, and trunk in infants or adolescents; it is atypical in a school-age child. It generally presents as erythematous lesions with yellow scaling rather than hypopigmentation.
(Choice G) Vitiligo presents as hypopigmented areas of skin that commonly involve the face but may be seen on any part of the body. The lesions are asymptomatic and do not present with scaling or itching.
Educational objective:
Tinea versicolor is a common skin eruption characterized by light macules on the trunk and upper extremities in adults. In children, the eruption typically involves the face. It is most noticeable after sun exposure as the surrounding skin becomes darker.