When Injection Therapy Can Help Relieve Painful Lesions
The porokeratosis is probably the result of direct pressure on the plantar surface of the skin but is not usually associated with an underlying bony condition. There is still some debate as to whether the underlying ducts of sweat glands are involved.
• Plantar verrucae. These benign epidermal neoplasms are caused by a variety of different human papillomaviruses (HPV) viruses. Papillomaviruses are species-specific double-stranded DNA viruses and approximately 46 different ones have been implicated in the formation of human warts. Plantar warts may appear as punctate single lesions, large mosaic warts or multiple seed warts on the weightbearing areas of the foot. It is easy to mistake them for solitary hyperkeratotic lesions or heloma milliare.
In general, plantar warts have vascular elements within the lesion and show pinpoint capillary bleeding when you debride them. When you find warts on the direct pressure bearing surfaces of the balls of the feet, they may be painful and interfere with normal gait. Warts tend to show complete loss of the normal skin lines, whereas other keratotic lesions usually show radiating skin lines through the lesion.
Is Enucleation Enough For Keratotic Lesions?
There are basically two types of manual reduction of external hyperkeratotic tissues: debridement and enucleation. We use debridement for more superficial lesions, such as localized or generalized callus, hyperkeratoses and verrucae.
Enucleation is the technique you can use to remove the deep central core of lesions, such as nucleated corns, intractable plantar keratoses, porokeratosis plantaris discreta or seed corns (heloma milliare). In most cases, it is essential to debride the overlying callus prior to enucleation.
The goal of this process is to remove as much of the deep keratin plug within the center of the lesion in order to reduce pressure and discomfort. If you remove too much of the keratinous buildup, the skin may feel very tender, especially upon weightbearing. When you remove insufficient keratinous material, your patient may continue to have pain immediately after treatment.
In using enucleation, you may be able to reduce the pain level and make these lesions more tolerable for patients. However, in my opinion, most keratotic lesions do not resolve with this form of conservative therapy.
Pertinent Pearls On Injection Therapy
It may be worthwhile to treat certain keratotic lesions or conditions, such as the intractable plantar keratosis, porokeratosis, fibroma or keratodermas, with intradermal or intralesional injections.
The most common agents used for injection therapy, along with the local anesthetic, include corticosteroids and sclerosing agents. It may be necessary to employ a local infiltrative nerve block with a local anesthetic agent prior to giving an intralesional injection in the lower extremity. Since injections into the plantar aspect of the foot may be extremely painful, you may give a posterior tibial nerve block prior to any other injection on the sole area of the foot.
In many cases, you may mix the local anesthetic agent with the medication and then inject the combination of the agents into or directly below the painful lesion. Using skin coolants, such as ethyl chloride, will greatly decrease the patient’s perception of pain from the needle penetrating through the skin.
Additionally, you may actually inject some plantar foot lesions from a dorsal approach if you can use a long needle that passes between the metatarsals at the level of the lesion. In many cases, the patients report this is somewhat less painful than injecting directly into the plantar lesion from below.