Should You Worry About Your Congenital Mole? Expert Insights

Congenital mole

Hello, doctor.
I have a question.
I have a mole on the front of my thigh that I was born with.
It has a small black dot in the center, surrounded by a brown irregular shape, measuring about 0.5 cm.
The surface is flat and it has been with me for over forty years without increasing in size, and there has been no inflammation or ulceration of the skin.
I always wear long pants and haven't exposed it to much sunlight.
Should I see a doctor about this mole? Can moles that are present at birth become cancerous, especially since the shape is irregular? Thank you.

Mimi, 40~49 year old female. Ask Date: 2021/05/16

Dr. Wu Yuxin reply Dermatology

If you're concerned, have a dermatologist check it out.

Reply Date: 2021/05/16

More Info

When it comes to congenital moles, also known as congenital nevi, it's understandable to have concerns, especially when there are characteristics that might raise red flags, such as irregular shape or color. Based on your description, you have a congenital mole on your thigh that has been present since birth, measuring approximately 0.5 cm, with a small black dot in the center and a brown irregular border. You mentioned that it has not changed in size over the years and has not shown any signs of inflammation or ulceration.

First and foremost, it's important to note that congenital moles are relatively common and can vary significantly in appearance. They are typically benign, especially if they have remained stable over time, as you described. However, the irregular shape and the presence of a darker center can be concerning features that warrant further evaluation.

The primary concern with any mole, particularly those that are congenital, is the potential for malignant transformation into melanoma, a serious form of skin cancer. While the risk of a congenital mole developing into melanoma is generally lower than that of an acquired mole, it is not zero. Factors that can increase the risk include changes in size, shape, color, or texture, as well as the development of symptoms such as itching, bleeding, or ulceration.

Given that your mole has remained unchanged for over forty years, this is a positive sign. However, the irregular shape is a factor that should not be overlooked. The "ABCDE" rule is a helpful guideline for assessing moles:
- Asymmetry: If one half of the mole does not match the other.

- Border: Irregular, scalloped, or poorly defined edges.

- Color: A variety of colors (brown, black, tan, red, white, or blue).

- Diameter: Moles larger than 6 mm (about the size of a pencil eraser) should be evaluated.

- Evolving: Any change in size, shape, color, or elevation, or new symptoms such as bleeding, itching, or crusting.

In your case, the irregular border and the presence of a small black dot may suggest that it would be prudent to consult a dermatologist for a professional evaluation. A dermatologist can perform a thorough examination and may recommend a dermatoscopic evaluation, which allows for a more detailed view of the mole's structure. If there are any concerns, they may suggest a biopsy to rule out any malignancy.

Additionally, while you mentioned that you have kept the mole protected from sun exposure by wearing long pants, it's important to remember that UV exposure is not the only risk factor for skin cancer. Genetic predisposition, personal history of skin cancer, and other factors can also play a role.

In summary, while your congenital mole has not shown signs of change or concern over the years, the irregular shape does warrant a professional evaluation. It's always better to err on the side of caution when it comes to skin health. Regular skin checks and being vigilant about any changes in your moles are essential practices for maintaining skin health. If you have any further questions or concerns, don't hesitate to reach out to a healthcare professional.

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