Axillary granular parakeratosis - Skin in Adult
AGP typically presents as erythematous, violaceous, or brown papules that occasionally coalesce into plaques. Lesions can be pruritic and friable. AGP has a relatively chronic course and can persist for several months or resolve spontaneously, but recurrence is common.
The etiology is unknown, but various theories include irritant or allergic contact reactions directed against a component of a deodorant or antiperspirant, occlusion, excessive use of creams, excessive sweating, and obesity. A related theory is that AGP is a protective mechanism in humid body regions exposed to mechanical irritation.
GP can occur in individuals of all ages and both sexes. However, it is more common in women between 40 and 60 years of age, with a female-to-male ratio of 25:1. Reports of cases in children have been 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.
R23.4 – Changes in skin texture
56585003 – Parakeratosis of skin
- Acanthosis nigricans usually presents with confluent velvety-tan plaques.
- Pemphigus vegetans or pemphigus vulgaris is usually more erosive.
- Chronic irritant dermatitis
- Lichen planus is usually pruritic.
- Tinea corporis tends to spread more rapidly over a course of weeks.
- Granuloma annulare – Usually no scale is present, and it tends to involve other areas of the body.
- Contact dermatitis is usually more pruritic.
- Seborrheic dermatitis
- Inverse psoriasis (see psoriasis)
- Darier disease – Lesions are typically greasy, keratotic papules, skin-colored or yellow-brown in color, forming large crusted and confluent plaques.
- Hailey-Hailey disease – Widespread flexural involvement, with hypertrophic and malodorous plaques and painful fissures.
- Pigmented and hyperkeratotic napkin dermatitis (PHND) – A type of chronic diaper dermatitis.
- Terra firma-forme dermatosis – Can be removed by rubbing with isopropyl alcohol.