Inflammatory skin disorder, with multiple small sites at sweat pores. Blockage of ducts causes sweat to escape into various levels of the skin and produce different inflammatory reactions. The most common type, known as prickly heat, results when sweat escapes into the epidermis. Pinhead blisters or pimplelike bumps occur mostly on the trunk and limbs and cause itching and burning. It mainly affects infants in tropical climates. See also perspiration, sweat gland