Dr Keith Hopcroft continues our series of fascinating but often unrecognised conditions
The case
‘What I don't understand, doctor,' said my patient, displaying her bikini areas, ‘is how these insects managed to bite me underneath my swimming costume.' Good point: she was showing me a rash which had developed about a week previously. The spots had appeared two days after she'd taken advantage of a warm day by playing with her young children in the garden and then relaxing in her outdoor hot tub. ‘I think they're fading now, but they have been really sore and itchy,' she explained.
The rash was maculopapular, with some pustules, and was largely confined to her bikini area, though some were evident in her armpits, too. Otherwise, she was well, and she was taking no medication.
The diagnosis
The clue here is the Jacuzzi – and the fact that the spots look like a folliculitis. Put the two together and you have ‘Jacuzzi folliculitis' – also known as hot tub, whirlpool or pseudomonas folliculitis, the latter name revealing the aetiology. Pseudomonas can be isolated from inadequately maintained hot tubs. The rash may easily be confused with insect bites, heat rash, acne and impetigo.
Typical features
The rash usually appears two to four days after exposure. It may itch or burn and is usually confined to the bathing costume area, though it may spread to intertriginous zones. It rarely recurs.
Treatment
Jacuzzi folliculitis is typically self-limiting, normally resolving in seven to 10 days without specific treatment. Rarely, the infection becomes chronic, in which case it resembles severe, infected eczema. In such cases – or when the original episode is severe – ciprofloxacin may be necessary.
Issues for the GP
GPs are used to making non-specific diagnoses to buy time and await events. They wouldn't do any harm in this case, but being able to come up with the correct label would prevent unnecessary oral or topical treatment and would ensure that the real culprit – the hot tub – is properly serviced.
Take-home point
Even the simplest skin rash merits a proper history if you want to refine your diagnostic skills.
Dr Keith Hopcroft is a GP in Laindon, Essex
Jacuzzi folliculitis Jacuzzi folliculitis
