Inherited epidermodysplasia verruciformis (ORPHA:302)
Epidermodysplasia verruciformis (EV) is a rare inherited genodermatosis characterized by chronic infection with human papillomavirus (HPV) leading to polymorphous cutaneous lesions and high risk of developing non melanoma skin cancer.
Epidemiology
The exact prevalence of EV is unknown; more than 200 cases have been reported in the literature so far.
Clinical description
The disease usually manifests during infancy (7.5% of cases), childhood (61.5% of cases) or puberty (22% of cases) with a progressive development of hyperpigmented or hypopigmented flat wart-like papules, irregular reddish brown plaques, seborrheic keratosis-like lesions and pityriasis versicolor-like macules on the trunk, neck, face, dorsal hands and feet (sun-exposed skin). Various HPV subtypes (HPV5 and HPV8 are found in 80% of cases) can be detected in the cutaneous lesions. Thirty to 60% of patients develop non-melanoma skin cancers, especially squamous cell carcinomas (SCC), during the fourth or fifth decades of life, mainly on sun-exposed areas. Black-skinned patients have a much lower incidence of skin cancer. Most SCC remain local; metastases are uncommon.
Etiology
EV can be caused by loss-of-function mutations in either of the 2 adjacent genes EVER1/TMC6 or EVER2/TMC8 (17q25.3) coding for membrane proteins that form a complex with the Zinc transporter protein ZnT-1 in the endoplasmic reticulum (ER) membrane of keratinocytes. The mutations in these genes lead to susceptibility to infection with specific HPV subtypes belonging to the beta genus, including HPV5, 8, 9, 12, 14, 15, 17, 19-25, 36-38, 47 and 49, which are ubiquitous and harmless to healthy individuals.
Diagnostic methods
Diagnosis is based on clinical and histological findings. Skin biopsy shows verruca plana-like lesions with mild hyperkeratosis, hypergranulosis and acanthosis of the epidermis. Keratinocytes of the upper epidermal layers are enlarged with perinuclear vacuolization and a typical blue-gray pallor. HPVs can be detected in keratinocytes using in situ hybridization or immunohistochemistry with anti-HPV antibodies.
Differential diagnosis
Differential diagnosis includes squamous cell carcinoma, acrokeratosis verruciformis (see these terms), tinea versicolor, and generalized verrucosis of other origin. In addition, an acquired epidermodysplasia verruciformis-like syndrome has been described in patients with impaired cell-mediated immunity, mainly HIV-infected subjects.
Genetic counseling
In most cases, transmission is autosomal recessive but sex-linked and autosomal dominant inheritance patterns have also been reported.
Management and treatment
Although permanent cure of EV cannot be achieved by any therapy at present, described treatment modalities include cryotherapy, topical imiquimod and 5-fluorouracil, systemic retinoids, interferon alpha, and 5-aminolevulinic acid photodynamic therapy. Surgical excision is the treatment of choice for SCC. Preventive measures, in particular sun exposure avoidance and photoprotection, are crucial for proper management.
Prognosis
Prognosis is favorable since skin tumors appear progressively and metastases are uncommon.

                            Last update: 
                            February 2010


                            - Expert reviewer(s): 
                            Pr Giovanna ZAMBRUNO