Don’t underestimate the “mole” on the sole of your foot!

Author: Fan Ruirui, MD, Xiamen University Xiang'an Hospital

Reviewer: Zhang Bo, Professor and Chief Physician, Peking University Third Hospital

It is not scary to have a mole, but it is important to have it in the right place. There is a mole on a certain part of your body that affects not only your fortune but also your health. Do you know where it is? That's right, it is the sole of your foot. Today, we will popularize the medical knowledge about moles to help you understand why moles on the soles of your feet need special attention.

1. What is a mole?

Moles, commonly known as freckles, are medically called pigmented nevi or melanocytic nevi. They are benign lesions caused by the proliferation of nevus cells (melanocytes). Pigmented nevi are relatively common in clinical practice, and their occurrence often has a familial tendency. Sunlight exposure, especially intermittent strong light exposure, is one of the important causes of the formation of pigmented nevi. Moles can be found all over the skin and mucous membranes of the human body, usually appearing as macules or papules with a diameter of less than 6 mm, with clear boundaries and uniform color. Among them, black, brown and blue moles are the most common.

Figure 1 Copyright image, no permission to reprint

2. What types of moles can be divided into?

Pigmented nevi can be divided into the following categories:

1. Junctional nevus: Nevus cells proliferate at the junction of the epidermis and dermis.

2. Intradermal nevus: Nevus cells proliferate only in the dermis.

3. Mixed nevus: It combines the characteristics of intradermal nevus and junctional nevus. Nevus cells proliferate both at the junction of the epidermis and dermis and in the dermis.

4. Blue nevus: It is formed by the proliferation of spindle-shaped nevus cells in the dermis and usually appears blue.

5. Recurrent nevus: refers to a pigmented nevus that reappears after treatment and requires regular follow-up observation.

Regardless of the type of pigmented nevus, the clinical practice usually adopts a follow-up observation strategy, unless they affect the appearance or have a tendency to malignant transformation, surgical excision should be considered.

3. Which part of the body’s mole is most likely to become malignant?

The risk of malignant transformation varies for pigmented nevi in ​​different parts of the body. Special attention should be paid to pigmented nevi on the limbs, fingertips and feet, especially those on the soles of the feet, which are more likely to become malignant due to long-term contact with shoes and socks and repeated friction and stimulation. When a mole is found to be rapidly enlarged in a short period of time, uneven in color, irregular in borders, accompanied by symptoms such as itching, erosion, exudation or bleeding, you should be highly alert to the possibility of malignant transformation and go to a regular hospital for a skin pathological biopsy in time to make a clear diagnosis and avoid delays in the disease.

It is worth noting that laser treatment is generally not recommended for pigmented nevi, because laser treatment can easily stimulate nevus cells and increase the risk of malignant transformation. Surgical excision is the effective way to cure pigmented nevi. In addition, the malignant transformation of pigmented nevi usually transforms into malignant melanoma. In recent years, the incidence of this disease has increased year by year and the prognosis is poor. Therefore, understanding the medical knowledge of pigmented nevi and regularly monitoring their changes are of great significance to maintaining skin health.

Figure 2 Copyright image, no permission to reprint

4. How to determine whether a mole on the sole of the foot shows signs of malignancy?

Early use of the "ABCDE" rule for morphological observation can help assess the possibility of malignant transformation of moles.

A (Asymmetry): Asymmetry. Malignant moles usually appear asymmetrical, often with irregular edges.

B (Border irregularity): The border is irregular. The edge of a pigmented nevus is usually smooth and even, while the edge of a malignant nevus is irregular and may appear notched or jagged.

C (Color variation): Color change. Pigmented nevi are usually single and uniform in color, while malignant nevi are mainly dirty and uneven in color.

D (Diameter): The diameter of a pigmented nevus is usually less than 6 mm, while a malignant nevus is usually larger than an ordinary nevus. For a nevus with a diameter exceeding 1 cm, it is best to perform a pathological examination to assess the possibility of malignancy.

E (Elevation): Some early malignant moles may have slight elevation at the lesion site.

In clinical practice, doctors use the "ABCDE" rule to screen out moles that are "suspected of malignancy" through morphological observation, and then perform a pathological biopsy to carefully observe the atypia of mole cells under a microscope to ultimately determine whether the pigmented nevus has become malignant.

5. What preventive measures can effectively reduce the risk of moles becoming malignant?

Not all moles will become malignant. Following the following suggestions can effectively reduce the risk of malignant changes:

1. Avoid excessive exposure to the sun, especially before working, laboring or traveling under the scorching sun, be sure to pay attention to sun protection to protect your skin from damage by ultraviolet rays.

2. Try to reduce friction and stimulation in areas with moles. For example, you can wear loose and comfortable clothes and shoes to reduce friction on the moles.

3. Remove moles scientifically. If pigmented moles affect your appearance, you should go to a regular hospital for surgical removal, and try to avoid using laser or other methods to remove moles on your own.

4. Regularly self-check moles using the "ABCDE" rule. If you highly suspect that a mole has become malignant, you should immediately go to a regular hospital for treatment. Once the malignancy is confirmed, surgical removal should be performed as soon as possible.

In short, moles are not scary. People with moles should not be afraid of them, nor should they take them lightly. Especially when you have moles on the soles of your feet, please go to a regular hospital for treatment in time. Let us pay attention to these "little marks" on the skin, examine the changes of each mole with a scientific attitude, understand the mystery of moles, and protect our skin health!