The patient is a 58-year-old woman who is seen for evaluation of an underarm rash first noted several months ago. On occasion, the eruption is pruritic. The patient stopped using antiperspirants because she believed that these may have played a role in causing the rash. The patient has adult-onset diabetes and is currently taking metformin. Examination of both axillae revealed multiple hyperpigmented papules with adjacent erythema. No similar lesions were noted elsewhere. A biopsy was performed.
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Axillary granular parakeratosis was first described in 1991 as a condition that clinically resembles Hailey-Hailey disease but has a distinctive histopathology manifesting compacted parakeratosis within the stratum corneum along with retention of keratohyaline granules.1 The investigators presented 4 patients with hyperpigmented to bright red patches and papules in the axillae that were pruritic. Subsequently, 2 more cases were documented in 1995.2 These investigators postulated that the condition resulted from contact dermatitis to antiperspirants. Scheinfeld and Mones retrospectively reviewed 18 cases diagnosed histopathologically with this condition and concluded that granular parakeratosis is an uncommon disorder that is most prevalent in obese white females.3 Given that granular hyperkeratosis has been reported to occur at other body sites, they questioned the causative link to antiperspirants.
Untreated, granular hyperkeratosis persists indefinitely. A variety of therapies have resulted in resolution or marked improvement. These include topical tretinoin,4 topical calcipotriene and ammonium lactate,5 topical corticosteroids,6 and isotretinoin.7
Case submitted by Stephen Schleicher, MD.
1. Northcutt AD, Nelson DM, Tschen JA. Axillary granular parakeratosis. J Am Acad Dermatol. 1991;24:541-544.
2. Mehregan DA, Vandersteen P, Silkorski L, Mehregan DR. Axillary granular parakeratosis. J Am Acad Dermatol. 1995;33:373-375.
3. Scheinfeld N, Mones J. Granular parakeratosis: pathologic and clinical correlation of 18 cases of granular parakeratosis. J Am Acad Dermatol. 2005;52:863-867.
4. Brown SK, Heilman ER. Granular parakeratosis: resolution with topical tretinoin. J Am Acad Dermatol. 2002;47:S279-S280.
5. Contreras ME, Gottfried LC, Bang RH, Palmer CH. Axillary intertriginous granular parakeratosis responsive to topical calcipotriene and ammonium lactate. Int J Dermatol. 2003;42:382-383.
6. Chamberlain AJ, Tam MM. Intertriginous granular parakeratosis responsive to potent topical corticosteroids. Clin Exp Dermatol. 2003;28:50-52.
7. Webster CG, Resnik KS, Webster GF. Axillary granular parakeratosis: response to isotretinoin. J Am Acad Dermatol. 1997;37(5 Pt 1):789-790.