Skin cancer can develop anywhere on the body, including in the lower extremities. 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.
We often view the sun's harmful rays as the primary cause of skin cancer; the condition is often found on parts of the body that receive the most sun exposure. Skin cancers of the feet, however, 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 important that the feet are checked regularly for abnormalities that might indicate evolving skin cancer.
Types and Symptoms
Some of the most common cancers of the feet are:
Basal Cell Carcinoma: Basal cell carcinoma frequently is seen on sun-exposed skin surfaces. With feet being significantly less exposed to the sun, it occurs there less often. This form of skin cancer is one of the least aggressive cancers in the body. It will cause local damage but only rarely spreads beyond the skin. Basal cell cancers may appear as pearly white bumps or patches that may ooze or crust and look like an open sore. On the skin of the lower legs and feet, basal cell cancers often resemble non-cancerous skin tumors or benign ulcers.
Squamous Cell Carcinoma: Squamous cell carcinoma is the most common form of cancer on the skin of the feet. Most types of early squamous cell carcinoma are confined to the skin and do not spread. However, when advanced, some can become more aggressive and spread throughout the body. This form of cancer often begins as a small scaly bump or plaque, which may appear inflamed. Sometimes there is a history of recurrent cracking or bleeding. Occasionally it begins as a hard projecting callus-like lesion. Though squamous cell cancer is painless, it may be itchy. Squamous cell cancer may resemble a plantar wart, a fungal infection, eczema, an ulcer, or other common skin conditions of the foot.
Malignant Melanoma: Malignant melanoma is one of the deadliest skin cancers known. Non-surgical treatments are rarely effective, and many remain experimental. This type of skin cancer must be detected very early to ensure patient survival. Melanomas may occur on the skin of the feet and on occasion beneath a toenail. They are found both on the soles and on the top of the feet. As a melanoma grows and extends deeper into the skin, it becomes more serious and may spread through the body through the lymphatics and blood vessels.
Malignant melanoma has many potential appearances, leading to its nickname, “The Great Masquerader.” This skin cancer commonly begins as a small brown-black spot or bump; however, roughly one third of cases lack brown pigment and thus appear pink or red. These tumors may resemble common moles; however, close inspection will usually demonstrate asymmetry, irregular borders, alterations in color, and/or a diameter greater than 6 mm. Melanomas may resemble benign moles, blood blisters, ingrown nails, plantar warts, ulcers caused by poor circulation, foreign bodies, or bruises.
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 patients for the early detection of both benign and malignant skin tumors.
Learn the ABCDE's 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.
Color - There may be more than one color. These colors may have an uneven distribution.
Diameter – The lesion is wider than a pencil eraser (greater than 6 mm).
Evolution - Any change — in size, shape, color, elevation, or another trait, or any new symptom such as bleeding, itching or crusting — points to danger.
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
Your podiatrist will investigate the possibility of skin cancer both through a clinical examination and with the use of a skin biopsy. A skin biopsy is a simple procedure in which a small sample of the skin lesion is obtained and sent to a specialized 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.