What are the classifications of prickly heat?

Miliaria is a common skin condition, which is mainly classified into the following types according to its causes and clinical manifestations: 1. **Miliaria crystallina (clear miliaria)**: Also known as crystal miliaria, it commonly occurs in newborns, children who are excessively wrapped, and those experiencing fever with increased perspiration. It presents as small, transparent, superficial vesicles without inflammatory reaction. Lesions are asymptomatic, easily ruptured, and after rupture, the exudate is absorbed, leaving fine desquamation. 2. **Miliaria rubra (red miliaria)**: Also known as red miliaria, it frequently occurs during summer and autumn, especially in obese infants. Commonly affected areas include the forehead, neck, chest, and back. It presents as dense, pinhead-sized papules or papulovesicles with a rounded apex, surrounded by erythematous halos. Patients may experience sensations of burning or pruritus. Lesions usually dry up and desquamate within several days. 3. **Miliaria pustulosa (pustular miliaria)**: Also known as pustular miliaria, it commonly occurs on the flexural surfaces of the limbs, scrotum, and the backs of bedridden patients. It presents as dense papules or papulovesicles with superficial pustules on the apex. The pustules are usually sterile or contain non-pathogenic cocci. Pruritus is often prominent. 4. **Miliaria profunda (deep miliaria)**: This type commonly occurs in individuals with severe and recurrent miliaria rubra. It presents as dense skin-colored papulovesicles that enlarge during perspiration and become less noticeable when sweating ceases. Pruritus is generally absent.