Requested DocAlert: Picture Quiz Poll: A Ring Around the Buttocks


Information sourced from BMJ:

BMJ 2016;352:i1147
[Free full-text BMJ article PDF]


Spot Diagnosis

Annular, scaly, erythematous rash on the buttocks and thighs

Krishna Sumanth Mukkanna, Natalie Stone

Correspondence to: K S Mukkanna

A 63 year old woman presented with a three month history of an itchy, annular, scaly, erythematous rash on both buttocks and upper posterior thighs. The rash had not responded to topical betamethasone valerate 0.122% ointment.


What is your diagnosis and how can it be confirmed?


Allergic contact dermatitis to a toilet seat, which can be confirmed by a patch test (including a test using scrapings from patient’s toilet seat).


Allergic contact dermatitis to wooden toilet seats was recognised as a form of regional dermatitis before the 1960s. It has been described in relation to wood, paint, and varnish components of toilet seats. Resurgence in this striking pattern of dermatitis has recently occurred as wooden seats have become more popular again. Toilet seat allergic contact dermatitis should be considered in patients presenting with dermatitis confined to the posterior upper thighs, a strikingly geometric eruption across the buttocks, or the dramatic ring distribution seen in this patient.

Patient consent obtained.

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