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Q. An 80-year-old man was admitted into intensive care unit after a stroke. He was immobile and dependent on a ventilator to breathe. Five days after admission, he developed an erythematous rash on his back and complained of a burning sensation and an intense itch. He was treated with a combination of topical antifungal and steroid cream with little improvement. What could be the cause of this rash?
What is your diagnosis?
A. The presenting skin problem and symptoms are consistent with heat rash often referred to as miliaria or prickly heat due to the itchy irritated feeling on the affected area. When the sweat ducts that open to the surface of the skin are occluded, blocking the normal production and removal of sweat, clear, fluid-filled blisters and papules may develop. This type of heat rash is called miliaria crystalline. With prolonged and total obstruction, sweat leaks into the deeper layers of the epidermis, triggering a local inflammatory reaction. The term miliaria rubra connotes the reddened skin and you may notice red streaks that extend across the lower back as shown in the picture. In severe cases, heat rash may involve the dermis, causing miliaria profunda. Miliaria pustulosa describes pustules due to inflammation and bacterial infection.
Several factors can affect normal functions of sweat gland and sweat production causing heat rash and they are:
Environment: Hot, humid weather
Overheating: This can affect people who are confined to a hospital bed for long periods, especially if they are wearing tight clothing, sleeping under an electric blanket.
Physical activity: Intense exercise that causes increased perspiration
Certain fabrics: Clothing, pad, sheets, incontinent product that causes friction and do not allow normal evaporation of perspiration.
Medications: Certain prescription medications that enhance sweat gland function such as beta-blockers and opiates.
Heavy creams and ointments: Certain lubricants, such as petrolatum, can be occlusive (especially mixed with other topical powder and paste), blocking the outflow of sweat ducts.
Autonomic dysfunction: People with spinal cord injuries and other neurological disorders may develop autonomic dysfunction characterized by excessive sweating.