Acrokeratosis verruciformis


Acrokeratosis verruciformis

Description, Causes and Risk Factors:

A congenital disorder characterized by warty papules of the hands, feet, knees, and elbows.

Acrokeratosis verruciformis is a very rare, heritable hyperkeratotic dermatosis that was originally described by Hopf in 1931. It is characterized by multiple, localized, symmetrical, flat, skin-colored, wart-like lesions, typically observed on the dorsum of the hands and feet. Small groups or isolated papules may develop on the knees, elbows, forearms, and also on other parts of the body. The forehead, scalp, flexures, and the oral mucosa are never affected. The lesions are usually present at birth, but they may appear later in infancy as papules or at puberty as ichthyosis. In some cases, onset may be delayed until the fifth decade of life.

Lesions identical to those of acrokeratosis verruciformis can also be observed in patients with acral Darier disease or even in relatives of such patients. A possible relationship between acrokeratosis verruciformis and Darier disease has been suggested, nevertheless they are still considered to be distinct both genetically and histologically.

The two diseases may be similar clinically, but the acral lesions in Darier disease, though initially non-dyskeratotic, have every likelihood of developing dyskeratosis at a later age, whereas acrokeratosis verruciformis remains non-dyskeratotic and non-acantholytic throughout life. Basically, the keratinization process in acrokeratosis verruciformis is exaggerated but normal, whereas in Darier disease it is accentuated, altered and faulty.

Considering the possible genetic relationship between the two diseases, a recent report has shown that acrokeratosis verruciformis can arise from a missense mutation in ATP2A2, encoding the sarcoendoplasmic reticulum Ca2+ ATPase2 pump, which is also defective in Darier disease.

acrokeratosis verruciformis

A mutation in ATP2A2, a gene situated on band 12q23-q24 encoding for sarcoplasmic/endoplasmic reticulum Ca2+ ATPase2 (SERCA2), is the cause of Darier disease. SERCA2 is a calcium pump of sarcoplasmic/endoplasmic reticulum that plays a role in intracellular signaling. Considering the possible relationship between the 2 diseases, one report has shown that acrokeratosis verruciformis can arise from a missense mutation in ATP2A2. This finding suggests that the 2 diseases are allelic disorders with phenotypic expression of different severities. A more recent study provides evidence for genetic heterogeneity of acrokeratosis verruciformis and demonstrates that mutations in genes other than ATP2A2 are responsible for acrokeratosis verruciformis in some patients.

In 2003, researchers identified a heterozygous P602L mutation in the ATP2A2 gene in a family affected with acrokeratosis verruciformis for 6 generations. This mutation predicts a nonconservative amino acid substitution in the ATP-binding domain of the molecule. The mutation segregates with the disease phenotype in the family and was not found in 50 controls. Moreover, functional analysis of the P602L mutant showed that it has lost its ability to transport Ca2+. This result demonstrates loss of function of the SERCA2 mutant in acrokeratosis verruciformis, thus providing evidence that acrokeratosis verruciformis and Darier disease are allelic disorders.

Acrokeratosis verruciformis has been described in individuals of many races. No sex predilection has been reported for acrokeratosis verruciformis.

Symptoms:

Symptoms may include the following:

    Dry, rough, skin-colored or reddish-brown, flat-topped, or warty papules resembling flat warts are observed, particularly on the dorsum of the hands and, at times, on the dorsum of the feet.

  • Papules also may be found on the knees, elbows, forearms, or lower legs.

  • Small groups or isolated papules may develop on other parts of the body.

  • Papules sometimes are more easily felt than seen.

  • Palmar skin may be thickened and may show punctate keratosis or punctiform breaks in dermatoglyphics, identical to those observed in persons with Darier disease or Grover disease.

  • Nail involvement, including longitudinal splitting, striations, and subungual hyperkeratosis, also may be seen.

Diagnosis:

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.

Treatment:

The only treatment considered effective for acrokeratosis verruciformis is superficial ablation. Although in general, treatment is not recommended, several medical and surgical treatments have been suggested. Applications of retinoic acid have been helpful for some affected individuals, and cryotherapy or destructive lasers such as CO2 or Nd:YAG have been tried. Lesions tend to persist throughout life and become more prominent after prolonged sun exposure. Transformation to squamous cell carcinoma has been reported in two cases and there is one report that suggests a possible linkage of acrokeratosis verruciformis and nevoid basal cell carcinoma syndrome.

NOTE: The above information is for processing purpose. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition.

DISCLAIMER: This information should not substitute for seeking responsible, professional medical care.

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