A 75-year-old woman comes to the office for evaluation of a rash on her chest. She is nonambulatory and lives in a nursing home. One week ago, the patient had a fever with a productive cough of yellow sputum. She was started on azithromycin for presumed pneumonia with slight improvement in her symptoms. However, her caregivers have noted significant sweating over the past 5 days and a diffuse rash on her chest, abdomen, and back. She has a history of hypertension, stroke, and dementia.
Her vital signs are within normal limits. Skin examination is shown in the image below. There is no warmth or tenderness around the skin lesions.

Which of the following is the most likely diagnosis?

Question

A 75-year-old woman comes to the office for evaluation of a rash on her chest.  She is nonambulatory and lives in a nursing home.  One week ago, the patient had a fever with a productive cough of yellow sputum.  She was started on azithromycin for presumed pneumonia with slight improvement in her symptoms.  However, her caregivers have noted significant sweating over the past 5 days and a diffuse rash on her chest, abdomen, and back.  She has a history of hypertension, stroke, and dementia.
Her vital signs are within normal limits.  Skin examination is shown in the image below.  There is no warmth or tenderness around the skin lesions.

Which of the following is the most likely diagnosis?

Quizplus · Accepted Answer

11ec193a_9793_1895_853d_c32bafef8228_MD0002_00 This patient's skin lesions are consistent with miliaria ("heat rash"), which is due to blockage of the eccrine sweat ducts in the setting of increased heat or humidity. Miliaria is most common in newborns and young children, but it can also occur in bedridden adults with fever, increased sweating, or tight-fitting clothing. Obstruction of the sweat glands in the superficial stratum corneum causes miliaria crystallina, which presents with small, thin-walled, noninflammatory vesicles that resemble dewdrops. Ductal obstruction deeper within the epidermis causes miliaria rubra, which is characterized by erythematous papules or pustules, often with significant irritation or pruritus ("prickly heat"). Miliaria pustulosa is similar to miliaria rubra, with more significant pustules on an erythematous base. Miliaria profunda is due to ductal obstruction in the dermis and presents with asymptomatic flesh-colored papules and/or pustules. Treatment of all miliaria includes sweat reduction with cool baths, compresses, or light and loose clothing. miliaria rubra (Choice A) Folliculitis (bacterial or fungal) is due to inflamed hair follicles and typically causes an erythematous, pustular eruption. The lesions can be asymptomatic or cause significant pruritus and pain. This patient's absence of significant inflammation and erythema makes folliculitis less likely. Folliculitis (Choice B) Herpes zoster usually presents with grouped vesicles or pustules on an erythematous base in a dermatomal distribution. This patient's nondermatomal distribution is not consistent with herpes zoster. Herpes zoster (Choice C) Keratosis pilaris is due to retained keratin from plugged hair follicles that can sometimes cause pruritic or pustular lesions in the upper arms (most common), face, trunk, and lower extremities. It worsens in cold and dry climates and can appear similar to goose bumps. Keratosis pilaris (Choice E) Urticaria causes diffuse and well-circumscribed erythematous patches, papules, or plaques associated with significant pruritus. Urticaria Educational objective: Miliaria ("heat rash") is due to blockage of the eccrine sweat ducts in the setting of excess heat or humidity. It most often occurs in children but can also occur in bedridden adults with fever, increased sweating, or tight-fitting clothing. Typical lesions can range from small, thin-walled vesicles to erythematous papules and pustules. __________ References: Miliaria-rash after neutropenic fever and induction chemotherapy for acute myelogenous leukemia. (http://www.ncbi.nlm.nih.gov/pubmed/22068785) Miliaria crystallina in an intensive care setting. (http://www.ncbi.nlm.nih.gov/pubmed/14723716)

A 75-Year-Old Woman Comes to the Office for Evaluation of a Rash