Diagnosing And Treating A Longstanding Heel Lesion

Author(s): 
Kathleen Satterfield, DPM, FACFAOM, MAPWCA

You walk into the room to see a well-dressed 48-year-old businesswoman sitting in the treatment room. She has her right foot cradled in her hands and is massaging the heel. You notice the stylish high heels on the floor beside her.

    “You cannot imagine the pain that I feel, doctor,” she says before you even ask a question. “It feels as though I have a little dagger pressing against my heel. How can there be so much pain from such a tiny little corn?”

    When you get a closer look at her foot, you see the patient has applied a pad of skived moleskin. It is not a bad home treatment and may have been suggested by a previous podiatric physician.

    By this time, a patient seeking treatment for a “porokeratosis” or “IPK” is frustrated and is “doctor shopping.”

    Her history and physical exam show that she has had the 2 mm diameter lesion for six months. The patient says it has increased in size since it was debrided by another DPM. She has had a succession of podiatrists call it a seed corn, a porokeratosis, an intractable keratosis, an IPK and a benign tumor. She calls it excruciating and wants it gone. Your patient wants to know if you can help her for longer than three months at a time.

    You ask the patient when the lesion first appeared. The patient thinks for a moment before she answers tentatively. “I think it started when I got a stone bruise when I was training for a half marathon about 12 years ago,” she notes. “It has been getting worse ever since in spite of having it cored out every two to three months. I am getting really frustrated.”

Key Questions To Consider

1. What essential question does one still need to ask to help make the diagnosis?
2. What question should you ask about the location of pain?
3. What feature of this condition differentiates it from other conditions in your differential?
4. What is the differential diagnosis?

Answering The Key Diagnostic Questions

1. Is the lesion under a weightbearing surface?
2. Does it feel like there is a sharp point turned upward, like a knife, into the sole of the foot?
3. There is a white ring around the keratinized core.
4. The differential diagnoses for porokeratosis include an intractable porokeratosis (IPK), palmoplantar wart, punctate porokeratosis and callus.

A Closer Look At Porokeratosis

One of the biggest problems is terminology. Not all podiatric physicians speak the same language. This patient has a hard, keratinized lesion that has developed on the non-weightbearing portion of the heel. This is a porokeratosis or what we know as a porokeratosis. If it were in a weightbearing location, podiatrists would call it an intractable porokeratosis (IPK).

    The long held thought that a porokeratosis was a plugged sweat gland has been disproved by multiple scientific methods, including electron microscopy and histologic examination under conventional microscopy. Unfortunately, for unknown reasons, the myth that the porokeratosis is a plugged sweat gland is still being taught at at least one of the podiatric medical schools today even though this has been disproved.

    When I started researching this subject, I reached out to the dermatopathology experts in podiatry: Brad Bakotic, DPM, DO, Bryan Markinson, DPM, and G. “Dock” Dockery, DPM.

    “In 10 years in my lab, I have seen probably thousands of cases of punctate keratoderma, tens of thousands of IPKs and over 100,000 deep palmoplantar warts, but I have seen only fewer than 20 cases of true ‘punctate porokeratoses,’” notes Dr. Bakotic.1

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