CLINICAL HISTORY:

Signs and symptoms:  A 70 year old female presents with a several month history of hyperpigmented pruritic lesions in bilateral axillae.

Previous Treatment:  None.

Other information:  Her past medical history is significant for arthritis, thyroid disease, diabetes, and hypertension. Her medications include pioglitazone, calcium, valsartan and a thyroid medication. She denies any changes in her soap or laundry detergent. The patient's lesions persist despite switching brand of deodorant. She denies dryer sheet usage but uses a scented fabric softener. She also has no known drug allergies.

PHYSICAL EXAM:

A well appearing female with dark brown flat topped papules coalescing into plaques in bilateral axillae. Moderate scale is present and the lesions are more prominent in the left axilla than the right. No fissures or erosions are apparent.

Right axilla. Demonstrating hyperpigmented papules coalescing into plaques.

Magnified view of left axilla.

LABORATORY TESTS:

None.

DERMATOHISTOPATHOLOGY:

A shave biopsy from the left axilla reveals a compact stratum corneum with extensive parakeratosis. Nummerous fine keratohyalin granules are interspersed in the stratum corneum. Perivascular lymphocytic infiltrate is present in the superficial dermis. PAS staining is negative for hyphae.

H&E

H&E

DIFFERENTIAL DIAGNOSIS:

1.   Hailey-Hailey
2.   Acanthosis Nigricans
3.   Contact Dermatitis
4.   Granular Parakeratosis
5.   Inverse Psoriasis

SCROLL DOWN FOR ANSWER AND DISCUSSION.

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:

1. Srivastava M, Cohen D. Axillary Granular Parakeratosis. Dermatology Online Journal 2004; 10(3):20

2. Wallace CA, Pichardo RO, Yosipovitch G, Hancox J, Sangueza OP. Granular parakeratosis: a case report and literature review. Journal of Cutaneous Pathology 2003; 30:332-335

3. Metze D, Rutten A. Granular parakeratosis: a unique aquired disorder of keratinization. Journal of Cutaneous Pathology 1999; 26:339-352

4. Scheinfeld NS, Mones J. Granular parakeratosis: Pathologic and clinical correlation of 18 cases of granular parakeratosis. JAAD 2005; 52(5):863-867

5. Weedon D, Strutton G. (2002) Skin Pathology. China: Elsevier

Additional Comment:

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