Verruca vulgaris (common warts) is a non cancerous skin disease caused by a human papilloma virus (HPV) infection. The most common type of HPV, resulting in verruca vulgaris are HPV-2 and HPV-4. Other less common types include HPV-1, HPV-3, HPV-27 and HPV-57. It is a common childhood infection that is transmitted through direct skin to skin contact or via autoinoculation. Warts are commonly spotted in areas of frequent usage and minor trauma like back of toes/fingers and on the knees.
Verruca vulgaris is usually benign and most often occurs in areas that endure frequent mild trauma (e.g. fingers, fingernails, hands, knees and face). Hands are most commonly affected due to the increased probability of direct contact with HPV contaminated fomites. Autoinoculation is mainly observed in young children due to their inherent tendency to touch and scrape the surfaces of the already present warts leading to the spread of viral particles to unaffected skin. The clinical manifestation is strongly dependent upon the location of infection. Mild pain is reported in cases where warts are present in weight-bearing regions like the back of the feet. Morphological characteristics of common warts include :
The clinical presentation often helps in accurate diagnosis of warts. Skin biopsy of warts is generally not performed. The most important feature to look out for include:
Histological tests to detect and identify the structural proteins are mainly conducted when the warts are treatment resistant or when presented in immunocompromised patients. Low sensitivity is the major disadvantage of this test. Molecular analytical techniques like southern blot hybridization is more sensitive and specific for detecting and identifying the HPV type. Polymerase chain reaction (PCR) can be used to detect the presence of specific viral DNA. However, it should be noted that HPV can only be detected in relatively younger lesions.
HPV infection does not have a cure in modern medicine and therapies are mainly available for removal of warts. Patients respond differently towards different treatment and none is found to be 100% effective  . The course of treatment mainly depends upon the site of infection and sometimes more than one treatment method is required for effective management . Medical intervention is often necessary for individuals with spreading, extensive and painful warts or persistent warts aged over 2 years. The least invasive, time consuming and pricey methods are to be tried first before going in for costly and invasive procedures.
Usage of topical agents, intralesional injections and systemic agents are some of the noninvasive procedures that are available. Many topical agents are available for treating common warts. Application of topical agents is generally done by a trained personnel under medical supervision. Salicylic acid (SCA) is one of the important topical agents used for treating warts . SCA can be applied in many forms, liquid, or as a plaster or as SCA impregnated tape. Another topical agent in common use is cantharidin. It is a blistering agent extracted from the blister beetle. Contact with cantharidin results in epidermal necrosis and blistering which in turn help in the destruction of warts. It is used as a mono therapy agent or as an add-on therapy agent (1%) in combination with Podophyllum (5%) and SCA (30%) in collodion base. Formerly vitamin A was also used as a topical agent for treating common warts . Dibutyl squaric acid commonly termed as squaric acid dibutyl ester (SADBE) and diphencyclopropenone (DCP) are the other two contact immunotherapueatic agents used to treat warts. Trichloroacetic acid is used as a tissue necrotic agent to remove isolated warts by tissue destruction.
Treatment of isolated lesions is carried out using laser surgery and electrodesiccation with curettage or both. The major disadvantage of these procedures are that at times it may cause permanent scarring. Electrocautery and cryosurgery with liquid nitrogen (-196ºC) are the other two extremely effective but painful treatment options. The procedure involves the careful application of liquid nitrogen using cryospray or cotton bud applicator to the affected area covering 1-2 mm of surrounding normal skin. The procedure has to be repeated every 1-4 weeks depending on the size and severity of the infection for at least 3 months for complete removal of warts.
Carbon dioxide laser has been yet another high-precision technique used to remove warts via incision and excision of tissues with subsequent sealing of minute blood vessels. Better prognosis with a less chance of postoperative morbidity and related complications are the major plus points of carbon dioxide laser treatment. Another major advantage of CO2 laser therapy is its excellent long term results. This method is mainly used to manage intraepithelial neoplastic lesions. The excision can be performed following two different methods:
Warts are most common among children and in teenagers between ages 18 and 20. The prognosis is relatively fair and recurrence is mainly reported in immunocompromised patients. Resistance towards treatment and recurrence of infection is frequently encountered while managing HPV infections in immunocompromised patients. External factors like persistent localized trauma (e.g. in patients who are athletes, mechanics, butchers) are considered as risk factors for contracting the infection and for the recurrence of HPV infection. New HPV warts reappear in about 35% of cases within 1 year of primary infection. Spontaneous disappearance of warts without scarring occurs in one half and two-third of cases within the first and second year of infection respectively . The disappearance of wart without scarring is termed as spontaneous regression or involution. Scarring is the common side effect of removal of warts by medical intervention and such practices should avoid to prevent the formation of multiple scars in case of recurrence. Common warts beneath the fingernails (subungual warts) are difficult to treat as most of treatment options available are ineffective and may also lead to nail damage.
HPV is a double-stranded DNA virus with a circular genome enclosed in an icosahedral protein cover. Warts are generally seen on the back of phalanges or on the knees. The major HPV types reported are HPV-2 and HPV-4. The other types of HPV causing warts are HPV-1, HPV-3, HPV-27 and HPV-57. The identification of the type of HPV does not help in the treatment of warts . Major sites of infection include regions enduring frequent mechanical stress and strain resulting in minor epithelial damage such that the virus can gain access to the otherwise impenetrable barrier. Transmission occurs mainly through direct contact or indirectly via fomites. Using common swimming pools and bathrooms may lead to the spread of infection, where the virus gain entry through the damaged skin . Patients already infected with HPV may get re-infected (autoinoculation) via scraping, shaving or by minor skin aberrations  .
Verruca vulgaris is universal in occurrence, concerning around 7 to 12% of the total population. HPV is capable of infecting individuals of all ages, but is most frequently seen in children with peak incidence during teenage years, after which there is a sharp decline . The prevalence of common warts varies dramatically in different age groups, with different geographic location and time. Verruca vulgaris accounts for about 70% of all the warts that are presented clinically . The prevalence of warts was estimated to be approximately 0.84% and 12.9% in the United States and Russia, respectively, based on the observations of two separate populations based studies in the respective countries.
Warts can affect the epithelial membranes anywhere in the body. They gain access via minute skin aberrations. The exact mechanism by which they reach the basal or proliferating squamous epithelium is not fully understood  . The presentation of warts occurs after a specific incubation period of the virus inside the host. The HPV, once inside the host injects its genome into the host cell leading to uncontrolled cell replication and increased blood supply to the site which in turn help them to multiply rapidly . The site of replication of HPV is restricted to differentiated epithelial cells of the upper region of the epidermis. HPV is incapable of penetrating beyond this level to have a systemic dissemination and infection. Viral particles can be observed in the basal layer also. Histopathologic studies of site of infection reveal the presence of pronounced papillomatous epidermis and overlying tiers of parakeratosis along with hypergranulomatosis. Other pronounced observations include presence of large pink inclusions in the upper epidermis, especially in the incidence of acral skin. Presence of vacuolated keratinocytes (also known as koilocytes) with a small shrunken nucleus encircled by a perinuclear clearing area are also observed. Smaller basophilic granules are also found in some lesions.
Most of the cases are benign with no manifestations, especially in immunocompetent individuals. In such individual antibody mediated immunity provides protection and cell mediated immunity helps in regression of already present infection. Immunocompromised patients with HIV infection or those who have undergone kidney transplant or other organ transplantation have a higher risk of contracting infection with lesions that are resistant to treatment. Recommendations for preventing infections in such patients include
Verruca vulgaris (common wart) is a common, epidermal lesion caused by infection with human papillomavirus (HPV) of skin areas that frequently endure minor trauma. They are often seen in areas beneath the nail and cuticle. Over 100 types of HPV are known to cause the infection. Warts are mainly transmitted by direct contact or by autoinoculation. Presently there is no treatment available to cure the infection. Removal of warts using topical agents, systemic agents, surgical methods, intralesional injections, laser treatment, cryotherapy and electrodessication are prescribed in cases of substantial spreading of warts or when they persist over 2 years. Major risk factors for contracting infection include usage of common showers, occupational meat handling and immune suppression.
Verruca vulgaris (common wart) is a non-cancerous skin growth that appears on the top layer of skin as a result of localized human papilloma viral (HPV) infection. HPVs are small DNA viruses that infect the skin and mucous membranes. Warts are mainly seen in children and young adults. Most of the warts have a rough texture with light or dark nodulated surface. The spread of infection mainly occurs through direct contact with warts of other individuals or through fomites contaminated with viral particles. Autoinoculation occurs when the infection spread to other part of the body in an already infected person by touching or scratching of warts. The main sites of infection include hands, fingers/toe beds and knees.
Common warts are generally harmless and spontaneously disappear and therefore treatment is not required in most of the cases. Approximately 65% of warts goes away within 2 years of infection without any medical intervention. However, it should be noted that there is always a risk of enlargement and spreading of infection to other areas via autoinoculation (self-inoculation).
Medical attention is required in the presence of widespread/symptomatic /persistent or spreading warts over 2 years. Spontaneous resolution is difficult and resistance to treatment occurs in adults, immunocompromised patients (e.g. HIV infection and organ transplant patients) and those with persistent warts .
Treatment options available include usage of topical agents, systemic agents, intra lesional injections, cryotherapy, laser therapy, electro dessication and surgical excision. Warts in nail and toe bed areas are usually resistant to treatment. Liquid nitrogen can be used in such areas (cryotherapy).