Miliaria Rubra

General Information
Miliaria Rubra, also known as prickly heat or sweat rash is a common skin condition affecting infants and adults in hot and humid environments. Miliaria occurs when the sweat gland ducts are blocked due to bacteria or dead skin cells. The obstruction of the sweat glands causes sweat to leak into the deeper layers of the epidermis causing the inflammatory reaction. Papules can occur within days of exposure, but tend to appear after months. Itching and stinging are the main symptoms caused by the small papules. Efforts aimed at reducing sweating helps resolve the lesions within days. The health-care provider may recommend the use of medications if the rash is more severe. Treatments include calamine lotions, anhydrous lanolin and topical steroids.

Epidemiology
Occurs in as many as 30% of people who move to tropical climates

Etiology
Sweat leaks into the subcorneal layers because of ductal blockage

Pathogenesis
Sweat goes into the epidermis and upper dermis causing inflammation around the pores

Clinical
Pruritic or prickly small papules

Histology
Spongiosis and spongiotic vesicles in the stratum malpighian. Periductal inflammation present

Bibliography
1. “Heat Rash” (Online). January 2008. http://www.mayoclinic.com/health/heat-rash/DS01058/DSECTION=7 (visited: March 25, 2008) 2. “Miliaria” (Online). January 2007. http://www.emedicine.com/DERM/topic266.htm (visited: March 25, 2008)

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 Miliaria Rubra