Pruritic plaques in the axillae

CORRECT DIAGNOSIS:

Granular Parakeratosis

DISCUSSION:

Granular Parakeratosis is a unique disorder of keratinization. It has been reported in children but primarily occurs in women over 50years of age. Lesions are characterized by unilateral or bilateral brown plaques or papules primarily in intertriginous regions. It typically affects intertriginous areas such as the axillae, groin, abdominal, intermammary, and perianal regions.
The disorder may be caused by a number of different factors. Physiologically, a defect of profilaggrin to filaggrin during the process of cornification has been suggested. Filaggrin acts as an adhesion matrix for keratohyalin granules during normal cornification. Fungal infections may play a role in the etiology due to location. Other more well-established triggers include mechanical irritation, humidity, soaps, and antiperspirant use.
Typical histologic presentation is extensive parakeratosis with keratohyalin granules interspersed in the stratum corneum and a superficial perivascular infiltrate.

Differential diagnosis of granular parakeratosis includes pemphigus vegetans, acanthosis nigricans, contact dermatitis, tinea corporis, inverse psoriasis, and Hailey-Hailey.

TREATMENT:

Treatment of this condition includes the following topical medications: antifungals, antibiotics, steroids, retinoids, and vitamin D analogs. Behavioral modifications such as discontinuing and altering deodorants along with cryotherapy have also shown improvement. Spontaneous resolution of lesions has also been reported.

REFERENCES:

Srivastava, M., & Cohen, D. (2004). Axillary granular parakeratosis. Dermatology Online Journal, 10(3), 20. PMID: 15584299

Wallace, C. A., Pichardo, R. O., Yosipovitch, G., Hancox, J., & Sangueza, O. P. (2003). Granular parakeratosis: A case report and literature review. Journal of Cutaneous Pathology, 30, 332-335. PMID: 12881466

Metze, D., & Rutten, A. (1999). Granular parakeratosis: A unique acquired disorder of keratinization. Journal of Cutaneous Pathology, 26, 339-352. PMID: 10441859

Scheinfeld, N. S., & Mones, J. (2005). Granular parakeratosis: Pathologic and clinical correlation of 18 cases of granular parakeratosis. Journal of the American Academy of Dermatology, 52(5), 863-867. PMID: 15823526

Weedon, D., & Strutton, G. (2002). Skin pathology. China: Elsevier.

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