Am Fam Physician. 2024;110(4):419-420
Author disclosure: No relevant financial relationships.
A 10-year-old boy presented with a rash that developed 2 days earlier on his lower extremities and then spread to his buttocks, abdomen, back, and arms (Figure 1). It was not present on his feet, hands, or face. The patient reported pruritus and said that some areas of rash were painful. He did not have a fever or any other symptoms.
His mother reported no recent changes in detergent, body wash, or soap. She was concerned about cases of hand-foot-and-mouth disease at her son's school. She said that he had spent time in their hot tub recently, but it had been cleaned thoroughly before use. The patient's mother and father developed similar rashes 1 day after their son's rash appeared.
QUESTION
Based on the patient's history and physical examination, which one of the following is the most likely diagnosis?
A. Chickenpox.
B. Fifth disease.
C. Hand-foot-and-mouth disease.
D. Hot tub folliculitis.
E. Tinea corporis.
DISCUSSION
The answer is D: hot tub folliculitis, a skin infection of the hair follicles associated with soaking in a hot tub. Children are more susceptible to the condition than adults. Hot tub folliculitis develops after exposure to Pseudomonas aeruginosa in warm, wet areas such as inadequately chlorinated hot tubs or swimming pools.1
The rash begins as an eruption of red papules on the trunk and extremities that can become tender nodules. It is typically more pustular than vesicular and may be associated with fever and malaise. Hot tub folliculitis is generally a self-limiting, benign condition that does not require treatment.2
Chickenpox, caused by the varicella-zoster virus, is highly contagious and often affects all household members who have not had the disease or been vaccinated. The rash is vesicular and pruritic and often begins with macules followed by the classic vesicles. The incubation period of chickenpox ranges from 10 to 21 days; this is longer than that of hot tub folliculitis, which is 1 to 2 days after exposure to contaminated water.3
Fifth disease is caused by human parvovirus B19 and generally occurs during the winter and spring. It presents as a mild rash and mainly occurs in children 10 years and younger. The disease presents with the classic erythematous “slapped-cheek” rash on the face.4 Children may also have headache, fever, and rhinorrhea.4
Hand-foot-and-mouth disease can present as a macular or vesicular rash and commonly occurs on the hands and feet of infants and children. The self-limited rash is caused by coxsackievirus A16 and A17.5
Tinea corporis (ringworm) is a fungal infection caused by dermatophytes. The feet and groin are spared. The infection can manifest as one or more circular, erythematous, pruritic lesions with well-defined margins and scaly, raised edges. Associated plaques and patches may also be present. Tinea corporis is typically treated with antifungal ointment.6
| Condition | Characteristics |
|---|---|
| Chickenpox | Varicella-zoster virus infection; vesicular pruritic rash that begins with macules followed by vesicles |
| Fifth disease | Human parvovirus B19 infection; erythematous rash on the cheeks |
| Hand-foot-and-mouth disease | Infection of coxsackievirus A16 and A17; macular or vesicular rash on the hands and soles of the feet |
| Hot tub folliculitis | Pseudomonas aeruginosa infection; multiple pustular perifollicular lesions on the trunk and extremities; may be associated with fever and malaise |
| Tinea corporis | Dermatophyte infection; one or more circular, erythematous, pruritic lesions with well-defined margins and scaly, raised edges |
The author thanks Marianne Mallia, ELS, MWC, and other Scientific Publications staff with Mayo Clinic for editing and assistance with preparation of the manuscript.
