Skin cancer can develop anywhere on the body, including in the lower extremities. However, skin cancers of the feet have several features in common. Most are painless, and often there is a history of recurrent cracking, bleeding, or ulceration. Frequently, individuals discover their skin cancer after unrelated ailments near the affected site.
There has been increased awareness over the years of the rising incidence of the skin cancer, melanoma. Concerns have centred around the relationship between excess sun and ultraviolet light exposure as risk factors for developing melanoma. Although anyone at any age can develop melanoma, it is most often diagnosed in adult and elderly patients. You may not think of your legs and feet as areas for concern, but 30 percent or more of melanomas develop on these areas
Skin cancers of the feet are more often related to viruses, exposure to chemicals, chronic inflammation or irritation, or inherited traits. Unfortunately, the skin of the feet is often overlooked during routine medical examinations, and for this reason, it’s important that the feet are checked regularly for abnormalities that might indicate evolving skin cancer.
A melanoma typically includes a pigmented or darkened lesion that has changed in size, shape, colour, texture, or has an uneven colour or asymmetrical border. However, one type known as amelanotic melanoma is non-pigmented, and can resemble a non-healing wound on the foot. Melanoma beneath nails can appear as a pigmented streak or brown discolouration of the skin adjacent to the nail. They may resemble benign moles, blood blisters, ingrown nails, plantar warts, ulcers caused by poor circulation, foreign bodies, or bruises.
While most cases are diagnosed by a dermatologist, an increasing number of cases are being identified by podiatrists and orthopaedic specialists. They may notice an asymmetrical, unevenly coloured mole on the sole of the foot, or a darkened streak under a patient’s toenail. The next step would be a biopsy of the suspected lesion or referral to a dermatologist to rule out melanoma.
Even though people with fair skin and a tendency to sunburn quickly are more at risk, there is a form of melanoma that can develop on darker skin. This often affects the soles, palms, and nail beds.
When to Visit a Podiatrist
Podiatrists are uniquely trained as lower extremity specialists to recognize and treat abnormal conditions on the skin of the lower legs and feet. Skin cancers affecting the feet may have a very different appearance from those arising on the rest of the body. For this reason, a podiatrist’s knowledge and clinical training is of extreme importance for the early detection of both benign and malignant skin tumours.
Learn the ABCDs of melanoma. If you notice a mole, bump, or patch on the skin that meets any of the following criteria, see a podiatrist immediately:
- Asymmetry – If the lesion is divided in half, the sides don’t match.
- Borders – Borders look scalloped, uneven, or ragged.
- Colour – There may be more than one colour. These colours may have an uneven distribution.
- Diameter – The lesion is wider than a pencil eraser (greater than 6 mm).
To detect other types of skin cancer, look for spontaneous ulcers and non-healing sores, bumps that crack or bleed, nodules with rolled or “donut-shaped” edges, or scaly areas.
Diagnosis and Treatment
This type of skin cancer must be detected very early to ensure patient survival. As it grows and extends deeper into the skin, it becomes more serious and may spread through the body via the lymphatic system and blood vessels.
Your podiatrist/orthopaedic specialist will investigate the possibility of skin cancer both through a clinical examination and a biopsy. The biopsy is a simple procedure in which a small sample of the skin lesion is obtained and sent to a specialised laboratory where a skin pathologist will examine the tissue in greater detail. If a lesion is determined to be cancerous, your podiatrist will recommend the best course of treatment for your condition.
Prevention of skin cancer on the feet and ankles is similar to any other body part. Limit sun exposure, and make sure to apply appropriate sunscreen when you are outdoors and your feet and ankles are exposed. Foot melanoma is one of the deadliest cancers, but routine foot self exams can increase early detection and or survival. If ever you’re in doubt, check it out!