Lichen Propicus or Prickly Heat

This has nothing to do with lichen. It is a congestive or inflammatory disorder of the sweat follicles of the skin. It occurs as the result of the stimulant action of heat upon the surface. It is therefore common in hot countries, but not rare in this climate. "Prickly heat" is generally described as an eruption of numerous papillae of vivid red color, about the size of a pin's head, without redness of the skin generally, often interspersed with vesicles and accompanied by a peculiar tingling and pricking sensation, which may be almost intolerable, and is excited and intensified by heat, warm drinks, flannel, etc. The disease attacks chiefly the parts covered by the clothes, the arms, legs, breast, thighs, flanks, and the upper part of the forehead.

The treatment is the same as that for miliaria.