Tinea Versicolor (Pityriasis Versicolor)

Velvety, tan, or pink macules or white macules that do not tan.
Fine scales that are not visible but are seen by scraping the lesion.
Central upper trunk the most frequent site.
Yeast and short hyphae observed on microscopic examination of scales.
General Considerations
Tinea versicolor is a mild, superficial Malassezia furfur infection of the skin (usually of the trunk). This yeast is a colonizer of all humans, which accounts for the high recurrence rate after treatment. It is not understood why some patients manifest the spore and hyphal form of the organism and the clinical disease. The eruption is often called to patients' attention by the fact that the involved areas will not tan, and the resulting hypopigmentation may be mistaken for vitiligo. A hyperpigmented form is not uncommon.
Clinical Findings
Lesions are asymptomatic, but a few patients note itching. The lesions are velvety, tan, pink, or white macules that vary from 4–5 mm in diameter to large confluent areas. The lesions initially do not look scaly, but scales may be readily obtained by scraping the area. Lesions may appear on the trunk, upper arms, neck, face, and groin.
Large, blunt hyphae and thick-walled budding spores (“spaghetti and meatballs”) may be seen when skin scales have been cleared in 10% KOH. Fungal culture is not useful.
Differential Diagnosis
Vitiligo usually presents with larger periorificial lesions. Vitiligo (and not tinea versicolor) is characterized by total depigmentation, not just a lessening of pigmentation. Vitiligo does not scale. Pink and red-brown lesions on the chest are differentiated from seborrheic dermatitis of the same areas by the KOH preparation.
Treatment & Prognosis
Topical treatments include selenium sulfide lotion, which may be applied from neck to waist daily and left on for 5–15 minutes for 7 days; this treatment is repeated weekly for a month and then monthly for maintenance. Ketoconazole shampoo, 1% or 2%, lathered on the chest and back and left on for 5 minutes may also be used weekly for maintenance. Clinicians must stress to the patient that the raised and scaly aspects of the rash are being treated; the alterations in pigmentation may take months to fade or fill in. Tinver lotion (contains sodium thiosulfate) is effective. Irritation and odor are common complaints from patients. Relapses are common.
Sulfur-salicylic acid soap or shampoo or zinc pyrithrone-containing shampoos used on a continuing basis may be effective prophylaxis.
Ketoconazole, 200 mg daily orally for 1 week or 400 mg as a single oral dose, results in short-term cure of 90% of cases. Patients should be instructed not to shower for 8–12 hours after taking ketoconazole, because it is delivered in sweat to the skin. The single dose may not work in more hot and humid areas, and more protracted therapy carries a small but finite risk of druginduced hepatitis for a completely benign disease. Without maintenance therapy, recurrences will occur in over 80% of “cured” cases over the subsequent 2 years. Treatment with a single dose of 400 mg of oral fluconazole is also effective but more expensive.
Newer imidazole creams, solutions, and lotions are quite effective for localized areas but are too expensive for use over large areas such as the chest and back.

No comments:

Post a Comment