BACKGROUND:

Autoimmune progesterone dermatitis is a rare eruption that recurs monthly as progesterone levels peak during the menstrual cycle. Clinical and histologic features are variable, and the eruption is thought to represent a hypersensitivity response to endogenous progesterone.

METHODS:

We present the case of a 38-year-old woman with a pruritic intermittent facial eruption of 18 months' duration that recurred predictably in the days surrounding menses.

RESULTS:

The histology showed interface dermatitis with features of both erythema multiforme and urticaria. Intradermal injection of medroxyprogesterone acetate was positive. Her symptoms responded to antihistamine therapy.

CONCLUSION:

This unusual case is particularly distinctive both in terms of the histologic findings and the response to therapy.