When A Patient Presents With A Lower Extremity Rash

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Answering The Key Questions In Diagnosis

1. “Have you recently spent time in a hot tub or spa?”
2. Pseudomonas folliculitis, which is sometimes referred to as “hot tub dermatitis.”
3. Insect bites, scabies infestation, viral eruptions, drug or contact allergies, psychotic excoriations.
4. Perifollicular and papular lesions with some pustules.
5. As a general rule, the dermatitis will resolve spontaneously within 10 days. In severe cases, one may prescribe an oral antipseudomonal antibiotic. Clinicians may give an oral diphenhydramine hydrochloride for the pruritus.

When A Patient Presents With A Lower Extremity Rash
By Gary “Dock” Dockery, DPM, FACFAS

   Pseudomonal folliculitis may present with just a few to dozens of small (0.5 to 3 cm) spherical urticarial plaques, with a central papule or pustule on all skin surfaces exposed to long-term soaking in contaminated water. Typically, this condition occurs on the legs, groin area, waist, under the breast in females and on the back area. The lesions are usually concentrated in areas covered by a bathing suit and usually spare the head, neck and hands. The rash can be a polymorphous eruption or a mixture of follicular, maculopapular, vesicular or pustular lesions. These lesions are often extremely pruritic.

   Usually, no treatment is necessary as the folliculitis clears spontaneously in seven to 10 days. However, one can treat the intense itch with 25 to 50 mg of diphenhydramine hydrochloride at bedtime. Some patients may have recurrent crops of lesions over an extended period of up to three months, which may leave round spots of red-brown postinflammatory hyperpigmentation. For severely symptomatic patients or those who have re-exposure, one can use ciprofloxacin for five to seven days.

In Conclusion

   The differential diagnosis for a pruritic erythematous papular eruption is vast. Some of the more common possibilities include insect bites, viral exanthema, scabies, various fungal infections as well as allergic reactions to medication, foods, soaps, laundry detergents, topical preparations, plants or clothing.
In this case, careful examination with a magnifying lens was necessary to determine that the lesions were observable around hair follicles and that some were pustular. This helped to make this diagnosis. The primary descriptive characteristics of Pseudomonas folliculitis include papules, pustules, urticarial plaques, macules and vesicles.
Prevention requires meticulous cleaning of the hot tub and appropriate water chemical management.

Dr. Dockery is a Fellow of the American College of Foot and Ankle Surgeons, and a Fellow of the American Society of Podiatric Dermatology. He is board certified in foot and ankle surgery. He is the Chairman of the Board and Director of Scientific Affairs for the Northwest Podiatric Foundation for Education and Research in Seattle. Dr. Dockery is the author of Cutaneous Disorders of the Lower Extremity (Saunders, 1997) and Lower Extremity Soft Tissue & Cutaneous Plastic Surgery (Elsevier Science, 2006).

Editor’s note: For related articles, see “What You Should Know About Atopic Dermatitis” in the September 2005 issue of Podiatry Today.

Also be sure to check out the archives at www.podiatrytoday.com.


Suggested Reading 1. Bottone EJ, Perez AA: Pseudomonas aeruginosa folliculitis acquired through use of a contaminated loofah sponge: an unrecognized potential public health problem. J Clin Microbiol.; 31(3):480-3, 1993.
2. Chen S, Rudoy R: Pseudomonas Infections. eMedicine, March 27, 2006. Available online: www.emedicine.com/ped/topic2701.htm
3. Krivda S, Toner CB: Pseudomonas folliculitis. eMedicine. May 17, 2006. Available online: www.emedicine.com/DERM/topic356.htm
4. Silverman AR, Nieland ML: Hot tub dermatitis: a familial outbreak of Pseudomonas folliculitis. J Am Acad Dermatol; 8(2):153-156, 1983.

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