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VULVA: PSORIASIS
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Psoriasis |
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Psoriatic
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Histo 1 |
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Histo 2 |
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Psoriasis (Psoriasis vulgaris) is a non-infectious erythematous squamous disorder. In the vulva, this condition falls in the "Other Dermatosis" category of Nonneoplastic Vulvar Abnormalities. The etiology is unknown. Attempts to identify an immunologic basis have been unsuccessful. Inheritance may be multifactorial. It affects 1-2% of the population.
CLINICAL
Psoriasis is a systemic skin disease. It is characterized by pink to red plaques that are covered with silver-white scales. Lesions are commonly found on the elbows, knees, back, scalp and vulva, and may be exacerbated by stress. Lesions in the vulva can coalesce to form large areas of erythema with smaller satellite plaques. Pruritus is a common complaint. The nails are commonly involved, which show oncolysis and pitting. Severe psoriatic conditions will also have associated inflammatory bowel disease and arthritis.
Clinical signs useful in the identification of psoriasis include:
- Koebner phenomenon, which is the occurrence of new psoriatic lesions at the site of skin injury.
- Woronoff’s ring, which is a ring of peripheral blanching skin around a psoriatic plaque
- Auspitz’s sign, which are small bleeding points seen upon lifting of a psoriatic scale
If any question arises regarding diagnosis, a biopsy is necessary.
HISTOPATHOLOGY
The histologic features commonly present in psoriasis include acanthosis (uniform elongation of the rete ridges), parakeratosis and orthokeratosis, loss of the granular cell layer and the formation of spongiform pustules and parakeratotic microabscesses.
In the epidermis, the rete ridges are narrow towards the surface and broad at the base. Bridges may form among some of these ridges. Inversely, the papillary dermis is broadened and clubbed near the surface. The capillary vessels within the superficial dermis are slightly dilated and may have associated chronic inflammation. Neutrophils extravasate from these capillaries and are found in the thinned superficial epidermis (spongiform pustules of Kogoj). These neutrophils eventually aggregate in the parakeratotic layer, forming the Munro microabscess, which is characteristic of this condition.
Mitotic activity, commonly seen only in the basal cells, is typically increased in psoriasis. Mitotic figures are present in the parabasal (prickle cell) layers.
DIFFERENTIAL DIAGNOSIS
The differential diagnosis of psoriasis includes any erythematous plaque-like lesions occurring in the vulva, such as eczema, lichen planus, seborrhea, secondary syphilis, and Paget’s disease. Large pruritic psoriasic lesions can have a similar appearance to candidal infections. In this case, a wet mount can establish the presence of hyphae or budding forms. Paget’s disease and lichen planus do not form scales. Although scaling does occur in seborrhea the vulva is an unusual site for this condition. In any event, a biopsy may be necessary if the diagnosis is unclear.
TREATMENT
The treatment is related to the degree of disease. Mild conditions can be treated with tar shampoos (Tegrin, Neutrogena, Denorex) although this is a messy treatment for vulvar psoriasis. More often vulvar psoriasis is treated with steroids (hydrocortisone or triamcinolone cream 0.1%); in some cases, superpotent steroids may be necessary (clobetasol or halobetasol 0.05% for one to two weeks on thick scales). Vitamin D analogs and phototherapy have also been used. Emphasis should also be placed on reduction of any external stress.
REFERENCES
- Lever WF, Schaumburg-Lever G. Histopathology of the Skin (Seventh edition) J. B. Lippincott, Philadelphia, 1990, pp.156-161.
- Stone IK, Wilkinson EJ. Atlas of Vulvar Disease, Williams and Wilkins, Baltimore, 1995, p. 91-95.
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