There are gray spots in the armpits. When it gets hot, it turns red. It doesn't hurt or itch. There is no reaction in winter.

Many people have gray spots under their armpits, and when it is hot, these spots will turn red, but they are not painful or itchy. This is most likely a symptom of pityriasis versicolor. Pityriasis versicolor is a skin disease caused by Malassezia, and it is also a disease that has a certain impact on a person's image. Below, we will introduce you to the relevant knowledge about pityriasis versicolor in detail.

1. Causes

The pathogen is a type of lipophilic yeast called Malassezia. This type of fungus is a saprophytic fungus of normal skin. Only under certain special circumstances such as high temperature and humidity, local fat and sweat, and poor sanitary conditions, the parasitic density of Pityrosporum increases and the saprophytic yeast transforms into a hyphae type to cause disease. This bacterium only invades the superficial layer of the stratum corneum without causing an inflammatory reaction in the dermis. The disease is found throughout the world and is common in tropical and temperate regions with high relative humidity. Young people, especially young men, are more likely to develop pityriasis versicolor due to their frequent activities and excessive sweating. Pityriasis versicolor is also more common in patients who take corticosteroids for a long time, because the epidermal cell replacement cycle of these people is prolonged, which is conducive to fungal growth. Pityriasis versicolor will improve if the hormones are discontinued. In addition, physical weakness, malnutrition, diabetes and pregnancy can induce this disease.

2. Clinical manifestations

The initial lesions are circular punctate macules surrounding the pores, which gradually increase to the size of a nail plate with clear edges. Adjacent areas may merge into large irregular patches, with new macules appearing around them. The surface is covered with a small amount of bran-like scales that are easily peeled off, ranging from gray, brown to yellow-brown, and sometimes multiple colors coexist, resembling spots. The longer the time, the lighter the spots. The rash has no inflammatory reaction and occasionally causes mild itching. The lesions often occur on the chest and back, but may also affect the neck, face, armpits, abdomen, shoulders and upper arms. It is generally more common in young and middle-aged men. The course of the disease is chronic, with the rash decreasing or disappearing in winter but recurring in summer.

Treatment

1. Topical medications

2% ketoconazole lotion can be used externally for 7 to 10 days; 2% selenium disulfide lotion can be used externally for 7 to 19 days. Patients with smaller areas or those who cannot take oral antifungal drugs for various reasons can be given 1% bifonazole cream/gel, 2% miconazole cream, 2% ketoconazole cream, and 2% econazole cream, all of which have good therapeutic effects. Allylamine antifungal drugs such as terbinafine, butenafine, and naftifine are also effective. Amorolfine and ciclopirox olamine, as new antifungal drugs, can also be used in the treatment of pityriasis versicolor. Since pityriasis versicolor is difficult to cure and prone to relapse, intermittent repeated medication is required to ensure eradication of the infection. Sometimes, you can first clean with a lotion and then apply topical medication to improve the efficacy.

2. Systemic treatment

For patients with larger areas or recurrent attacks, oral azole drugs such as itraconazole, ketoconazole, and fluconazole can be given. Note that oral griseofulvin and terbinafine are poorly effective for pityriasis versicolor and should not be used to treat it.