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Miliaria is sweat retention due to obstruction of the sweat ducts. Depending on the level at which obstruction occurs in the sweat glands, miliaria is classified as miliara crystalline, miliara rubra or miliara profunda.
1.1 - MILIARIA CRYSTALLINE [1, 2]
It occurs during acute febrile illnesses with sudden sweating but can also be observed with classic sunburn. It presents as an asymptomatic outbreak of multiple superficial vesicular lesions with a clear content that look like dewdrops on the healthy skin of the trunk and abdomen, but also on the face in children. The obstruction is in the stratum corneum. Miliaria crystalline heals spontaneously within a few hours giving rise to a branny desquamation.
1.2 - MILIARIA RUBRA [1, 2]
It is the classic prickly heat, which occurs during prolonged exposure to hot, wet or dry climates in the presence of predisposing factors (Table I). The rash is made up of non-follicular papular and papulovesicular lesions that are uniform in size, 1 to 2 mm in diameter, bright red and associated with an inflammatory reaction. The condition is associated with itching and a burning sensation of varying intensity. The lesions may occur all over the body, but are most frequently observed on the sides of the trunk, on the back, the neck and in areas of friction (large folds...). In children and women using occlusive cosmetics, very profuse lesions are often seen on the face. Occasionally, the vesicles become pustular and are then called miliaria pustulosa (amicrobic lesions). If the bad conditions persist, the rash can become lichenoid, with papular curved lesions. Complications may occur at any time (Table II). The simple forms are characterised by pruritic, erythematous and desquamative areas evocative due to their location and exacerbation by heat. Obstruction occurs within the Malpighian layer. If conditions improve, the disease clears giving rise to a characteristic branny desquamation. This healing is followed by a hypohidrosis of the affected areas for two to three weeks, exposing patients to relapse.
1.3 - MILIARIA PROFUNDA 
It is a rare condition occurring after repeated episodes of miliaria rubra and observed primarily in the tropics. The rash is asymptomatic and consists of papules 1 to 3 mm in diameter on the trunk, but also on the extremities unlike the other forms of miliaria. The skin is generally dry. The obstruction occurs below the dermo-epidermal junction. Miliaria profunda is associated with axillary and inguinal lymphadenopathy and compensatory facial and axillary hyperhidrosis. These patients may develop tropical anhydrotic asthenia, which is the final stage of this major disorder of sweat secretion. It is characterized by general and functional signs such as asthenia, malaise, vomiting, faintness and tachycardia. The general signs are often in the forefront, leading to diagnostic errors. The symptoms may lead to malignant hyperthermia that can cause death if exposure persists.
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