Tinea versicolor, also known as sweat spots, is a mild, usually asymptomatic chronic fungal infection of the skin's stratum corneum. Skin lesions have pityroid scales, with decreased or increased pigmentation. Direct microscopic examination of typical fungal hyphae of tinea versicolor can confirm the diagnosis of skin lesions.
Disease knowledge
Symptoms
Skin lesions are most common in the chest, back, arms, and neck. Others include the face, abdomen, buttocks, armpits, groin, scalp, occipital area, etc. It worsens in summer and autumn, and decreases or subsides in winter. Start with small spots. Patients often unconsciously develop round or nearly round rashes ranging in size from corn, soybeans to fava beans. The edges are clear, level with the skin or slightly elevated. The surface is covered with extremely thin chaff like scales, which are glossy, especially when viewed from the light side, the skin lesions have strong reflectivity. The new skin lesion is dark in color, appearing gray, yellow, brown, light brown, or brown. The old skin lesions are pale and white in color. When both new and old skin lesions coexist, black and white patches appear as characteristic flower spots, which is a typical manifestation of tinea versicolor. When scales or skin lesions are removed and cured, there are temporary depigmentation spots left, and patients often mistake vitiligo for the condition and seek medical attention. Some patients have damage distributed along the hair follicles, resembling hair follicle papules, flat, slightly above the skin surface, covered with scales, and highly reflective. A small number of patients have patchy skin lesions, with only one to a few patches, but the area is relatively large. The surface scales are relatively thick, mostly dark brown or brownish brown, with a few light spots. Sometimes the area of skin lesions is so large that they are mistaken for normal skin. Patients generally have no conscious symptoms, with a few experiencing slight redness and itching. The disease is chronic, usually subsiding in winter and recurring in summer.
Inspection
Laboratory examination:
1. Direct microscopic examination. Scrape the scales and add 10% KOH solution for direct microscopic examination. Short, thick, blunt and slightly curved hyphae can be seen at both ends. Generally, the length is 10-40 μ m and the width is 2.5-4.0 μ m. There are piles of round or oval thick walled spores with a diameter of 3-8 μ m. Sometimes there are spores. A direct positive microscopic examination can confirm the diagnosis.
2. Cultivate on Sabouraud agar or other conventional media with 1-2ml of olive oil or other vegetable oil, inoculate with scales, and culture at 37 ℃. After 3 days, cream colored yeast like colonies will grow. Microscopic examination revealed that yeast like cells were predominant and budding. Cultivation is generally not a routine diagnostic procedure.
3. Wu's lamp examination showed golden fluorescence in the skin lesions and scraped scales of tinea versicolor. Other auxiliary examinations: Histopathology: Mild to moderate epidermal keratosis. There may be a small amount of monocyte infiltration in the dermis. Short, slightly curved, sausage like hyphae and piles of round or oval thick walled spores can be found in the middle or bottom of the stratum corneum, some of which can sprout. PAS and GMS staining provide clearer results.
Diagnosis: Tinea versicolor should be distinguished from seborrheic dermatitis, pityriasis rosea, anemic nevi, ringworm, melasma, and especially from vitiligo. Vitiligo does not have a specific location of onset. The development of skin lesions is slow, characterized by depigmentation rather than hypopigmentation, with clear edges and often darkened pigmentation. The fungal tests for the above diseases are all negative, making them easy to distinguish.
Treatment
Local use of exfoliating agents or other antifungal agents, such as compound remifentanil ointment or miconazole cream. Or use 20% to 40% sodium thiosulfate ointment twice a day for two consecutive weeks. It is recommended to take ketoconazole orally for large areas of tinea versicolor, 200mg per day, for 10 consecutive days. Fluconazole is taken 50mg once a day for 10 consecutive days. Itraconazole should be taken 200mg once a day for 5-7 consecutive days. The pigmentation reduction left after treatment is slow to recover to normal skin color, and exposure to ultraviolet radiation can accelerate recovery. Tinea versicolor is prone to recurrence or reinfection. The skin should be kept clean and dry regularly. The underwear, sweatshirts, bed sheets, pillowcases, etc. used by patients should be boiled and disinfected, or fumigated with formaldehyde (formalin).
Prognosis
When scales or skin lesions are removed and cured, temporary depigmentation spots remain. The disease is chronic, usually subsiding in winter and recurring in summer.
Prevention
1. Primary Prevention
(1) Develop good personal hygiene habits, such as frequent bathing and changing of underwear.
(2) Reasonable nutrition, as malnutrition can trigger this disease. Patients receiving corticosteroid therapy should pay attention to observation and prevention of this disease.
2. Secondary Prevention
(1) If left untreated, patients with tinea versicolor may not recover for many years, but as long as they take it seriously and persist in medication, it is also relatively easy to cure. Because tinea versicolor grows on the shallowest layer of the skin, topical antifungal drugs can be effective. Generally, 25% to 40% sodium thiosulfate solution can be applied, followed by 3% dilute hydrochloric acid solution 5 minutes after use. It is best to wash away the scales with hot water soap before applying the medicine. 10% glacial acetic acid solution, 1% clotrimazole, econazole cream or tincture can also be used, taken twice a day.
(2) To prevent recurrence after recovery, it is advisable to take medication for 2 weeks after the lesion has healed, and wear anti fungal clothes and pants at the same time, which can assist in treatment and have a preventive effect.
(3) BorelliD et al. reported that oral ketoconazole (a broad-spectrum antifungal agent) can not only treat tinea versicolor, but also prevent its recurrence.
(4) During the treatment period, shirts, underwear, bed sheets, pillowcases, etc. used by patients should be disinfected. The disinfection method can be boiling disinfection (15-30 minutes), hot washing with boiling water and sun exposure, or fumigation with formalin.