Corns.

Corns are a mechanically induced lesion that forms over or under a weight-bearing surface or structure ( Fig. 12.20 ). Corns (clavi) over the metatarsal heads are frequently mistaken for warts. The two entities can be easily distinguished by paring the callus with a #15 surgical blade. Warts lack skin lines that cross their surface and have centrally located black dots that bleed with additional paring. Examination with a hand lens shows a highly organized mosaic pattern on the surface. Corns also lack skin lines crossing the surface, but they have a hard, painful, well-demarcated, translucent central core ( Fig. 12.21A ). The core or kernel can be removed easily by inserting the point of a #15 surgical blade into the cleavage plane between normal skin and the core, holding the scalpel vertically, and smoothly drawing the blade circumferentially ( Figs. 12.21B–D ). The hard kernel is freed by drawing the blade horizontally through the base to reveal a deep depression. Pain is greatly relieved by this simple procedure. Lateral pressure on a wart causes pain, but pinching a plantar corn is painless.

Corns. An unusually large number of corns (plantar keratoses). These were all painful.

Debridement of corns. A, Corns (clavi) on the plantar surface are frequently mistaken for warts. B, Plantar surface depicted in panel A with soft and hard callus removed from the corn to reveal a deep depression. Examination with a hand lens shows no organized surface pattern as is seen in a plantar wart. C and D show the hard callus that was removed.

The treatment of corns is targeted at reducing the friction or pressure at a specific location. This can be accomplished with orthotic therapy and/or surgical correction of the osseous deformity creating the mechanical pressure point. Podiatric or orthopedic surgeons familiar with biomechanics and reconstructive surgery perform these corrective procedures.

Black Heel.

Horizontally arranged clusters of blue-black dots (ruptured capillaries or petechiae) may appear on the upper edge of the heel or anywhere on the plantar surface following the shearing trauma of sports that involve sudden stops or position changes ( Fig. 12.22A ). It is caused by the shearing force of the epidermis sliding over the rete pegs of the papillary dermis. At first glance, this may be confused with a wart or acral–lentiginous melanoma, but closer examination reveals normal skin lines, and paring does not cause additional bleeding ( Fig. 12.22B ). The condition resolves spontaneously in a few weeks.

A, Black heel (talon noir). Trauma causes capillaries to shear, resulting in a group of black dots; the appearance may be confused with warts. B, Paring the skin over the black dots in A reveals normal skin lines, proving that a wart is not present.

Black Warts.

Warts in the process of undergoing spontaneous resolution, particularly on the plantar surface, may turn black ( Fig. 12.23 ) and feel soft when pared with a blade. Cell-mediated immunity against virus-infected keratinocytes may take place in the process of regression of some warts.

Spontaneous resolution. Warts in the process of resolving may be painful and turn black. They are easily removed without anesthesia by using a curette.

Keratolytic Therapy (Salicylic Acid Liquid).

Keratolytic therapy with salicylic acid (over-the-counter) is conservative initial therapy for plantar warts. The treatment is nonscarring and relatively effective but requires persistent application of medication once each day for many weeks.

The wart is pared with a blade, pumice stone, or sandpaper (emery board). The affected area is soaked in warm water to hydrate the keratin surface; this facilitates penetration of the medicine. A drop of solution is applied with the applicator and allowed to dry. Solution may be added as needed to cover the entire surface of the wart. Penetration of the acid mixture is enhanced if the treated wart is covered with a piece of adhesive tape. Inflammation and soreness may follow tape occlusion, necessitating periodic interruption of treatment; consequently, the patient may be satisfied with the longer, more comfortable process of simply applying the solution at bedtime. White, pliable keratin forms in a few days and should be pared with a blade or worn away with abrasives such as sandpaper or a pumice stone. Ideally, the white keratin should be removed to expose pink skin; to accomplish this, an occasional visit to the office may be necessary.

Keratolytic Therapy (40% Salicylic Acid Plasters).

This is a safe, nonscarring treatment similar to keratolytic therapy with salicylic acid liquid except the salicylic acid has been incorporated into a pad. Salicylic acid plasters are particularly useful in treating mosaic warts that cover a large area.

The plaster is cut to the size of the wart. The backing of the plaster is removed and the sticky surface is applied to the wart and secured with tape. The plaster is removed in 24 to 48 hours, the pliable white keratin is reduced in the manner previously described, and another plaster is applied. The treatment requires many weeks, but it is effective and less irritating than salicylic acid and lactic acid liquid. Pain is relieved because a large amount of keratin is removed during the first few days of treatment.

Apple Cider Vinegar.

Many people claim success with this technique. Dip the wart in vinegar for 20 minutes. Apply Vaseline around the wart to protect the skin. Soak a small piece of cotton in vinegar and tape it to the wart overnight. Repeat each night until the wart is gone.

5-Fluorouracil (5-FU).

Application of 5-FU cream 5% under tape over 12 weeks resulted in an 85% clearance rate. The average time to cure occurred at 9 weeks of treatment.

Blunt Dissection.

Blunt dissection is a surgical alternative that is fast, effective (90% cure rate), and usually nonscarring. It is superior to both electrodesiccation–curettage and excision because normal tissue is not disturbed. (See Chapter 27 for surgical techniques.)

Imiquimod.

The immunomodulating drug imiquimod is more effective on thicker keratinized (nongenital) skin when occluded and used in combination with cryotherapy or a keratolytic agent. It is essential to debride the thick scale before applying imiquimod. The patient applies the cream daily and covers with tape (for ≥12 hours) to enhance penetration. Response to the use of imiquimod on the plantar surface is usually not preceded by an inflammatory reaction.

Suggestive Therapy.

Suggestive therapy generally works through the age of 10 years. A banana peel, potato eye, or a penny applied to the skin and covered with tape for a 1 to 2 week period has been effective in young children. Another technique is to draw the body part on a piece of paper and then draw a picture of the wart on the diagram. Crumble the pictures and then discard them.

Cantharidin.

Cantharidin mixtures are very effective for plantar warts. At the clinician’s office, apply Canthacur-PS (cantharone plus podophyllin 5% plus salicylic acid 30%) and allow the solution to dry. Avoid touching unaffected skin. Cover with occlusive tape (e.g., Blenderm) or moleskin and remove in 24 hours, or earlier if there is significant discomfort. A blister usually appears. Patients can relieve pain by breaking the blister. Patients may apply moleskin or felt padding around but not over the lesion to reduce pressure. In 2 to 3 days, remove the blister by excising with a scissors or using a curette after administering a local anesthetic. Repeat weekly if necessary.

Laser.

Various lasers (e.g., long-pulsed Nd-YAG, CO ₂ , and pulsed dye lasers) are available for treating resistant warts. The procedure is expensive and painful, often requiring local anesthesia.

Chemotherapy.

For years a variety of acids have been successfully used to treat plantar warts. This technique is occasionally used to treat warts that have recurred after treatment with other techniques and is occasionally used as initial therapy. Like keratolytic therapy, repeated application is required. Home application of acids is too dangerous; therefore weekly or biweekly visits to the clinician’s office are required. A number of acids may be used (bichloroacetic acid, trichloroacetic acid).

Treatment is as follows: The excess callus is pared. The surrounding area is protected with petrolatum. The entire lesion is coated with acid, and the acid is worked into the wart with a sharp toothpick. This procedure is repeated every 7 to 10 days.

Formalin.

This may be considered for resistant cases. Mosaic warts or other large involved areas may be treated with daily soaking for 30 minutes in 4% formalin solution. The firm, fixed tissue is pared before subsequent soaking. Lazerformaldehyde solution (10% formaldehyde) is commercially available for direct application to warts. There is a risk of inducing sensitization to formalin.

Cryosurgery.

Cryosurgery on the sole may produce a deep, painful blister and interfere with mobility. Repeated light applications of liquid nitrogen are preferred to aggressive treatment. Cryotherapy is equally effective when applied with a cotton wool bud or by means of a spray. A surgical blade is used to debulk the wart before freezing. Liquid nitrogen is applied until ice-ball formation has spread from the center to include a margin of 2 mm around each wart. A double or triple freeze–thaw cycle may be more effective than a single freeze. Treatment is given every 2 to 4 weeks for up to 3 months.

Cryosurgery.

Small periungual warts respond to conservative cryosurgery; warts that extend under the nail do not respond. The use of aggressive cryosurgery over superficial nerves on the volar or lateral aspects of the proximal phalanges of the fingers has caused neuropathy. Permanent nail changes may occur if the nail matrix is frozen.

Cantharidin.

Cantharidin (Cantharone) causes blister formation at the dermoepidermal junction but does not cause scarring. Adverse effects are postinflammatory hyperpigmentation, painful blistering, and dissemination of warts to the area of blistering.

In treatment, the solution is applied to the surface and allowed to dry and then occluded with tape. The patient is seen 1 week later for evaluation. Blisters are opened and the remaining wart is retreated. If blistering does not occur, then cantharidin is applied in one to three layers and covered with tape for 48 hours. Each layer should be dry before the next application of cantharidin. The treatment is very effective for some patients, but there are some warts that do not respond to repeated applications.

Keratolytic Preparations.

The same procedures described for treating plantar warts with salicylic acid and lactic acid paint and salicylic acid plasters are useful for periungual warts.

Blunt Dissection.

When conventional measures fail, blunt dissection offers an excellent surgical alternative (see Chapter 27 ). Local anesthesia is induced with 2% lidocaine without epinephrine around and under small warts. A digital block is required for larger warts. Hemostasis during the procedure is maintained by firm pressure over the digital arteries or with a rubber-band tourniquet. The nail should be removed only if the wart is very large and imbedded. The procedure is exactly the same as that described for blunt dissection of plantar warts.

Duct Tape Occlusion.

Duct tape occlusion therapy may be more effective than cryotherapy for common warts. To completely cover the wart, the tip of the finger is wrapped with duct tape. The tape remains in place for 6 days, is removed at home, is then reapplied in a similar manner 12 hours later, and remains in place for an additional 6 days. This procedure is repeated for up to 2 months.

Inflammatory Reactions.

Approximately 20% of patients develop inflamed lesions. They typically present as erythematous, edematous papules and papulonodules that may become pustular or fluctuant. Molluscum dermatitis presents as a pruritic eczematous eruption in the skin surrounding molluscum lesions. The dermatitis can be diffuse or nummular. Patients with a history of atopic dermatitis are more likely to have dermatitis associated with their lesions. Inflammation usually leads to regression of affected lesions and sometimes heralds clearance of the entire eruption, including lesions that do not develop inflammation. Patients with inflamed lesions are less likely to have an increased number of lesions during the next few months than those without inflamed lesions.

Curettage.

Small papules can be quickly removed with a curette and without local anesthesia in adults. Children might tolerate curettage after a lidocaine/prilocaine cream (EMLA) is applied for analgesia. The cream is applied 30 to 60 minutes before treatment. Bleeding is controlled with gauze pressure. Monsel’s solution is painful to use in an unanesthetized area in children. Curettage is useful when there are a few lesions because it provides the quickest, most reliable treatment. A small scar may form; therefore this technique should be avoided in cosmetically important areas.

Forceps.

Forceps may be utilized to gently pinch the molluscum lesions to extract the central core. This method can be utilized with eyelid lesions and children.

Cryosurgery.

Cryosurgery is the treatment of choice for patients who do not object to the pain. Most children will not tolerate cryosurgery. The papule is touched lightly with a nitrogen-bathed cotton swab or spray until the advancing, white, frozen border has progressed to form a 1-mm halo on the normal skin surrounding the lesion. This should take approximately 5 seconds. This conservative method destroys most lesions in one to three treatment sessions at 1- or 2-week intervals and rarely produces a scar.

Cantharidin.

Cantharidin, a chemovesicant extract from the blister beetle, is very effective, well tolerated, and safe in children. It penetrates the epidermis and induces vesiculation through acantholysis. Cantharidin is sparingly applied to each nonfacial lesion with the blunt wooden end of a cotton-tipped applicator. Contact with surrounding skin is avoided, and a maximum of 20 lesions are treated per visit. The treated areas are washed with soap and water after 4 to 6 hours, or sooner if burning, discomfort, or vesiculation occurs; therapy is repeated at 2- to 4-week intervals. Lesions blister and may clear without scarring. Occasionally, new lesions appear at the site of the blister created with cantharidin. Blistering and pain are mild to moderate. Pitted shallow depressions sometimes occur.

Potassium Hydroxide 5%.

Parents are instructed to apply the pharmacist-prepared solution twice daily with a cotton swab. A brief stinging may occur shortly after the application. Most lesions clear in 4 weeks.

Podophyllotoxin 0.5%.

The daily application of podophyllotoxin 0.5% may be tried for cases resistant to other therapies.

Hypoallergenic Surgical Adhesive Tape.

Tape is applied once each day after showering and is used each day until the lesion ruptures and the core is discharged. The average time to clearance is 16 weeks.

Salicylic Acid.

Salicylic acid solution applied each day without tape occlusion may cause irritation and encourage resolution.

MolluscumRx.

This topical solution and others like it are a natural treatment comprised of plant extracts. They are nonprescription treatments available through the Internet and sold in some physicians’ offices. Their efficacy has not been proved.

Laser Therapy.

Lesions on the genital area may be treated with the pulsed dye or the carbon dioxide laser.

Trichloroacetic Acid Peel in Immunocompromised Patients.

Patients with HIV infection who have extensive facial molluscum contagiosum infection were treated with trichloroacetic acid peels. Peels were performed with 25% to 50% trichloroacetic acid (average, 35%) and were repeated every 2 weeks as needed. A total of 15 peels were performed with an average reduction in lesion counts of 40.5% (range, 0% to 90%).