Etiology and pathogenesis Prickly heat, commonly known as prickly heat, is caused by the high temperature and humidity in the environment, excessive sweating is not easy to evaporate, sweat is epidermal keratin layer infiltration, resulting in sweat gland duct mouth occlusion, sweat retention in the sweat gland ducts due to increased internal pressure and rupture, overflowing sweat infiltration and stimulation of the surrounding tissue and the appearance of papules, pimples and small blisters at the sweat hole. The occurrence of prickly heat is not only due to high temperature and high humidity, but also due to other factors. It is thought that the occlusion of the sweat pores is a primary staphylococcal infection of the sweat pores, which is associated with a hot and humid environment. However, according to an experimental study in 1978, the occurrence of prickly heat is not related to excessive sweating, but to the proliferation of micrococci on the skin surface. Other scholars have also found in experiments that Staphylococcus epidermidis produces an extracellular polysaccharide substance that promotes the formation of prickly heat. Clinical manifestations Clinically, prickly heat is divided into the following types: 1. Crystal corn rash Also known as white prickly heat. The overflow of sweat occurs in the stratum corneum or under the stratum corneum, so the clinical manifestations are small superficial blisters of pinpoint size, thin-walled, clear, no redness around, easy to break after light rubbing, dry with tiny scales. The skin lesions mainly occur in the neck and trunk, and are dense and self-limiting. Generally no conscious symptoms. 2, red corn rash also known as red prickly heat. The overflow of sweat occurs slightly deeper in the epidermis. It is common in summer and has an acute onset. The clinical manifestation is the appearance of round and pointed pinhead-sized dense papules or papules in batches, surrounded by a mild red halo, with mild flaking after the rash subsides. The back of the hands, elbow sockets, neck, chest, back, under the breasts of women and the head, face and buttocks of children are the most common sites, with a mild burning, tingling and itching sensation. 3, pustular corn rash also known as pustular prickly heat. The pustules are composed of sterile or non-pathogenic cocci. It is common in the flexural side of the limbs, the perineum and other folds and the head of children. 4, deep corn rash, also known as deep prickly heat. Due to the rupture of sweat ducts in the upper dermis, especially at the division of the superficial dermis, dense non-inflammatory skin-colored blisters consistent with sweat holes are formed, and the surface is lusterless, and the rash is not obvious when the sweating stimulation is obvious. The rash is common in patients with severe and recurrent red rash, with no obvious self-conscious symptoms, usually on the trunk and extremities, but not on the face and palmoplantar areas. When the rash is widespread, compensatory sweating increases on the face, armpits, hands and feet. Other sweat glands basically lose their function, resulting in reduced or no sweating of the whole body skin. Heat exhaustion or tropical sweating exhaustion may occur clinically, with systemic symptoms such as fatigue, loss of appetite, lethargy, headache, and dizziness.