Identification and Treatment of Plantar Warts

Warts, or verruca, are common lesions that appear as benign proliferative hyperkeratotic areas in the cutaneous epithelium on the sole of the foot. Most commonly appearing at the metatarsal head level or in the heel area. Warts are caused by Human Papilloma Virus (HPV), with a variety of disease entities. Infection most likely occurs in the basal cell layers of the skin through fissures, cracks, cuts or other portals, whereby viral particles are picked up and transported to deeper cutaneous layers. HPV is "eptitheliotropic", that is, it can infect only human epithelial cells.

Verrucous lesions are described as being 1) solitary, or less than three lesions on one foot, 2) Mosaic, with a pattern of multiple grouped warts, or 3) recalcitrant, or any verruca that has failed to respond to any type of treatment.

Clinically, plantar verruca are also "endophytic", or larger than they might appear due to weight bearing involution within the epidermis. They appear as firm hyperkeratosis with tiny areas of pinpoint peticchiae or thrombosed capillaries, located centrally. Viral growth is limited to the epidermis proper but verrucal lesions may extend into dermal regions via rete ridges and pegs. It is for this reason that successful surgical excision requires removal of tissue down to, but not beyond the dermal basement membrane, separating skin from subcutaneous fat.

Treatment options include numerous variations, owing to both the resiliency of the virus and the less than optimal success rates of many methods.

The non-surgical methods include:
1) Roentgenotherapy, mostly abandoned today due to side effects of scarring, chronic ulceration and radiodermatitis.
2) Cryotherapy, utilizing liquid nitrogen or dry ice.
3) Injection therapy, utilizing Bleomycin, recombinant Alpha-2 interferon or 5-fluorouracil.
4) Electrodessication (hyfrection, fulguration).
5) Chemical destruction utilizing salicylic acid, formalin, cantharidin, retinoic acid, gluteraldehyde or podophyllin.

Surgical options include excision with a scalpel and suturing of the deficit. A less popular approach today due to the high incidence of painful scarring, bleeding and poor wound healing. Laser ablation with a CO2 creates tissue vaporization. High power and short exposure time effectively reduces the zones of thermal necrosis while providing a success rate of 62-90%.

Curettage is currently the most widely used surgical treatment option. Under local anesthesia, the lesion is debrided and a surgical dermal curette is employed to separate and lift the lesion free. Tissue is scooped out down to the level of the basement membrane and the peripheral tissue is excised around the crater. The base is then chemically cauterized. The reported cure ate is slightly higher than 90%.

Treatment options are abundant and vary with method and outcome. Care should be taken y the practitioner to evaluate the type and location of the lesions(s) in order to best select the most appropriate technique.