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This is a rare and distinctive skin rash that occurs in the axillay and occasionally in the submammary regions. It is characterized by erythematous hyperkeratotic plaques and papules. Although the cause is unknown, it is thought to represent an unusual reaction to topical anti-perspirants.


Gross Appearance and Clinical Variants
Histopathological Features and Variants
Differential Diagnosis



Granular parakeratosis - a unique acquired disorder of keratinization.

Metze D, Rutten A.

Department of Dermatology, University of Munster, Germany.

J Cutan Pathol 1999 Aug;26(7):339-52 Abstract quote

Axillary granular parakeratosis is a recently described condition presenting with erythematous hyperkeratotic papules and plaques.

We report on nine women and one man with eruptions not only localized to the axillae. Biopsy specimens were investigated by histology, immunohistochemistry, electron microscopy, immuno-electron microscopy, and in situ hybridization.

In general, the epidermis was hyperplastic and showed a well preserved stratum granulosum. In the upper dermis a discrete perivascular CD4+ T-cell infiltrate was found, CD1+ dendritic cells were absent from the epidermis. The distribution pattern of the epidermal keratins (keratin 5/14, 1/10) and the expression of involucrin was regular. The horny layer was excessively thickened and parakeratotic. The nuclear remnants showed marginal chromatin condensation and were reactive for the nick-end labeling technique using TdT-mediated dUTP-biotin. The corneocytes were characteristically replete with basophilic granules which showed both ultrastructural features of keratohyalin granules and immunoreactivity for filaggrin. Loricrin was expressed irregularly in small L-granules.

Granular parakeratotic cells revealed regular development of a cornified envelope while cell membranes and desmosomes remained undegraded. In conclusion, our studies on granular parakeratosis suggest a basic defect in processing of profilaggrin to filaggrin that results in a failure to degrade keratohyalin granules and to aggregate keratin filaments during cornification. Associated abnormalities of the cell surface structures and dysregulation of cornified envelope components may account for the retention hyperkeratosis.

Further studies are necessary to clarify the etiology of this unique, acquired disorder of keratinization that localizes to intertriginous areas and body folds.



Axillary granular parakeratosis.

Kossard S, White A.

Skin and Cancer Foundation Australia, Darlinghurst, NSW, Australia.

Australas J Dermatol 1998 Aug;39(3):186-7 Abstract quote

A 54-year-old woman had a 3 year history of a recurrent bilateral axillary rash during the summer months. Both axillae showed hyperkeratotic, fissured and cobblestone plaques. Skin biopsy showed the histology previously defined as axillary granular parakeratosis.

This finding may indeed represent an unusual contact reaction to anti-perspirants interfering with epidermal keratinization.


Submammary granular parakeratosis: an acquired punctate hyperkeratosis of exogenic origin.

Wohlrab J, Luftl M, Wolter M, Marsch WC. Department of Dermatology, Martin-Luther University, Halle-Wittenberg, Halle (Saale), Germany.

J Am Acad Dermatol 1999 May;40(5 Pt 2):813-4 Abstract quote

Granular parakeratosis is a histologic phenomenon that produces a characteristic clinical picture with multiple brownish and hyperkeratotic papules. In all 6 published cases of localized axillary parakeratosis, excessive use of different topical preparations (cream-type products, deodorants that include roll-on and stick types, antiperspirants, shampoos, bath soaps) was reported by the authors. The exact pathogenic causal relationships have not yet been resolved.

In the case reported below, we demonstrate for the first time that the macro- and micromorphological entities can also occur in the submammary region.



Axillary granular parakeratosis.

Northcutt AD, Nelson DM, Tschen JA.

Department of Pathology (Dermatopathology Section), Baylor College of Medicine, Houston, TX.

J Am Acad Dermatol 1991 Apr;24(4):541-4 Abstract quote

The term axillary granular parakeratosis is proposed for a unique axillary eruption with distinct histopathologic features.

Four middle-aged to elderly patients (three women, one man) had unilateral or bilateral, usually pruritic, hyperpigmented to bright red patches in the axillae. Biopsy specimens revealed severe compact parakeratosis with the stratum corneum measuring 80 to 250 microns in maximal thickness, maintenance of the stratum granulosum, remarkable retention of keratohyaline granules throughout the stratum corneum, and vascular proliferation and ectasia.

A contact reaction to an antiperspirant/deodorant is suspected as the cause. We speculate that the offending agent alters the maturation sequence of the stratum granulosum and stratum corneum, possibly by interfering with the degradation of filaggrin precursor to filaggrin units.

Axillary granular parakeratosis.

Mehregan DA, Vandersteen P, Sikorski L, Mehregan DR.

Pinkus Dermatopathology Laboratory, P.C., Monroe, Michigan 48161, USA.

J Am Acad Dermatol 1995 Aug;33(2 Pt 2):373-5 Abstract quote

We report two cases of axillary granular parakeratosis, which is a unique eruption involving the axilla that has distinctive histopathologic features.

Both of our patients had slightly pruritic, hyperpigmented patches in the axilla. The biopsy specimens revealed severe compact parakeratosis with maintenance of the stratum granulosum and retention of keratohyalin granules throughout the stratum corneum, which was markedly thickened and measured between 90 to 185 microns.

The exact etiology is not known, but this conditions is believed to represent a contact reaction to an antiperspirant or deodorant.



Acanthosis nigricans  

Weedon D. Weedon's Skin Pathology. Churchill Livingstone. 1997.
Fitzpatrick's Dermatology in General Medicine. 5th Edition. McGraw-Hill. 1999.

Last Updated 1/28/2002

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