I often see this condition in my practice and the question arises frequently enough for me to blog about it. Let’s discuss the similarity between the “seeded” corn and a callus before we discuss their differences. They are both thickened skin. They occur primarily on the bottom of the feet. They do inflict pain as they become thicker in layers. And they do require routine shaving to get relief.
So, what characteristics make the “seeded” corn and callus different? Well, let’s take the subject of the “seeded” corn first. The medical term for this condition is called porokeratosis. If you search the internet, you might find a type of porokeratosis that is mentioned with a circular red patch on the skin and has a thin raised halo around it. This lesion is not what will be discussing in this blog. We will be describing another type of porokeratosis. The bottom of the feet frequently present with a callused, well-circumscribed lesion that is usually yellow in color and it appears to have a center core, or “seed.” It is like a corn within a callus. Usually calluses arise from pressure created over a bony prominences. However, the porokeratosis grows in odd places, like in the arch or at the sulcus of the feet where there is no pressure at all. So there is no known cause to the condition. There is an old theory that it may arise from a plugged up sweat gland for there is a deep component to it at the center. The more accepted theory is that it has a genetic predisposition in certain individuals, for they present with not just one lesion, but many lesions to both feet. It hurts more than a regular callus would at times because of the deeper core at the center. When it thickens and since porokeratosis is deeper to the nerve endings, it causes more pain.
The regular calluses are diffused, thickened areas of skin. They form over bony prominences, at the bottom of the feet, heels or at the top of the toes. Certain causes of calluses are from poor foot structure, foot structure types, and poor fitting shoes. When there is enough pressure to the bones with weight-bearing or to a bone deformity, like hammertoes, the constant force to those areas form calluses.
Conservative measures are used as treatment for these calluses or porokeratosis. I shave them down to render instant relief for patients. I usually recommend that patients use lotion, padding and supportive shoes to minimize the discomfort in between visits. Most of the time, patients do well with the conservative approach. They would come back intermittently to get palliative foot care to obtain relief. But the long-term approach would be to use the custom orthotics with metatarsal pads to address the abnormal foot positioning and to off-load the pressure to the callused areas. The orthotics are an attempt to slow down the growth of these calluses and to minimize pain.
Dr. Dang H. Vu, DPM is a Baltimore Podiatrist with more than 18 years of experience. He completed his residency at Sinai Hospital of Baltimore, where he furthered his surgical expertise. He now holds privileges at Northwest Hospital. He offers services from three Baltimore Locations in Reisterstown, Towson and in the Rotunda Building in Hampden. You can find directions and request an appointment on his website FamilyPodiatryofMD.com