A flexural rash like this in an elderly incontinent patient
might have you thinking of irritant dermatitis or psoriasis or perhaps a
candida infection but the curious thing was it only occurred when she was
admitted to hospital from her nursing home with a chest infection. She would be
fine when she arrived but a couple of days later this rash would appear in the
groin and less so in the axillae, accompanied by a few annular lesions on her
trunk. It took a couple of admissions to work out that this was a flexural
fixed drug reaction to amoxicillin antibiotic she would be given for her chest
infection. This condition has also been described as Symmetrical Drug -related
Intertriginous and Flexural Exanthema SDRIFE . Various other drugs have been
reported as causing this distinctive flexural rash but Ampicillin is the
commonest. It is similar to systemic contact dermatitis where an individual is
initially sensitised to a contact allergen and is subsequently exposed to it
through a systemic route and develops a symmetrical localised dermatitis, often
on the buttocks and groin flexures. The classic cause was mercury exposure from
a broken thermometer where subsequent inhalation of mercury vapour caused a
rash that was colloquially known as the Baboon syndrome because of the red
bottom!
