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AGP, also known as intertriginous granular parakeratosis, is a rare benign acquired disorder of keratinization thought to result from an error in epidermal differentiation.
Granular parakeratosis (GP) is used to describe the presentation in body areas other than the axillae, such as the groin, chest, or neck.
Typically presents as erythematous, violaceous, or brown papules that occasionally coalesce into plaques.
Lesions can be pruritic and friable, with a relatively chronic course.
Can persist for several months or resolve spontaneously, but recurrence is common.
Etiology is unknown.
Possible causes include: irritant or allergic contact reactions directed against a component of a deodorant or antiperspirant, excessive use of creams, excessive sweating, obesity, and a protective mechanism in humid body regions exposed to mechanical irritation.
Can occur in individuals of all ages and both sexes.
More common in women between 40 and 60 years of age.
Has a female-to-male ratio of 25:1.
Associated with diaper use, excessive washing, and use of topical zinc oxide.
It occurs in all races and ethnicities.
Variants include follicular GP, which is confined to the follicle, and GP of the eccrine ostia, which has been associated with sweating or high temperatures.
In anecdotal case reports, GP has been associated with dermatomyositis, molluscum contagiosum, and cancer.