155 - Miliaria

Abstract

Miliaria is a benign, transient disorder caused by occlusion and resultant injury in the eccrine duct. It is subdivided into miliaria crystallina, miliaria rubra, and miliaria profunda, based on the level of obliteration. Miliaria crystallina (sudamina), the most superficial form, occurs with occlusion of the sweat duct in the stratum corneum. It is self-limiting and typically appears as clear vesicles without significant erythema. Miliaria rubra (‘prickly heat’) is the most common, presenting as numerous pruritic non-follicular papules or vesicles with surrounding erythema. The obstruction occurs within the eccrine duct in the stratum malpighii. Typically, it occurs on the trunk, neck, or back but can affect other areas and has been reported to occur under splints, braces, and military uniforms because of the warm occlusive environment. Miliaria profunda is uncommon, classically occurring at the dermoepidermal junction or dermis; however, advances in imaging have begun to cause physicians to question this understanding, raising the possibility of acrosyringial involvement. Miliaria profunda is typically seen after repeated cases of miliaria rubra in tropical settings. These patients can also have associated systemic symptoms related to overheating.