Nail Issues: What Does a Dark Spot on Your Nail Mean?

Nail problems?

Hello, Doctor.
While taking a shower, I accidentally noticed a small black dot under my left thumb nail.
I tried to wash it off, but after picking at it, it bled a little, and I think I might have removed a small piece of skin, which then disappeared.
However, I also noticed a dark area along the edge of the nail that seems to be darkening.
I read online that dark lines on nails might not be good and could indicate a mutation of melanin or some kind of poisoning in the body.
I'm not sure if I need to see a doctor about this.
My family suggested that the bleeding might be due to my picking at it or that the dark area was already there.
I was thinking of visiting a dermatologist on Monday for a follow-up regarding the medication I received for a bug bite and to check on this issue for peace of mind.
Thank you, Doctor.
Here is the area I just circled: https://ibb.co/QNXvsH0

Ling, 20~29 year old female. Ask Date: 2020/12/04

Dr. Hong Yuanbin reply Internal Medicine

Hello, based on your photo, it does appear to be caused by bleeding, likely from accidentally cutting yourself while trimming your nails.
It should not be related to a disease.
I recommend monitoring it for a few days, unless it continues to expand, in which case you should consult a dermatologist.
Thank you for your inquiry.

Reply Date: 2020/12/04

More Info

When you notice a dark spot on your nail, it can be concerning, especially if it appears suddenly or changes in appearance. The presence of a dark spot or line on a nail can have several potential causes, and understanding these can help determine whether you need to seek medical attention.

One common cause of dark spots under the nails is a condition known as a subungual hematoma, which occurs when blood collects under the nail due to trauma. This can happen if you accidentally hit your nail or if there is repetitive pressure on it. The dark color is due to the pooled blood, and it may be accompanied by pain or tenderness. If you noticed the spot after scratching or injuring the area, this could be a likely explanation.

Another possibility is a benign condition called a melanonychia, which refers to a brown or black pigmentation of the nail. This can be caused by various factors, including increased melanin production, which can occur due to genetics, certain medications, or underlying health conditions. In some cases, melanonychia can be a sign of a more serious condition, such as melanoma, a type of skin cancer that can develop under the nail.

If the dark spot is accompanied by other symptoms, such as changes in the nail's texture, shape, or growth pattern, or if you experience pain, swelling, or discharge, it is advisable to consult a healthcare professional. A dermatologist can perform a thorough examination and may recommend further tests, such as a biopsy, to rule out any serious conditions.

In your case, since you mentioned that you scratched the area and caused some bleeding, it is possible that the dark spot is related to that injury. However, the darkened area along the edge of the nail could also warrant further investigation, especially if it persists or changes over time.

It is a good idea to follow up with a dermatologist during your next appointment, as you mentioned you have a scheduled visit for a previous insect bite. Bringing up your concerns about the dark spot will allow the doctor to assess it in the context of your overall health and any other skin issues you may have.

In summary, while a dark spot on the nail can often be benign and related to trauma, it is essential to monitor it closely. If it does not improve, changes in appearance, or is accompanied by other concerning symptoms, seeking medical advice is the best course of action. Your health and peace of mind are important, and a professional evaluation can provide clarity and reassurance.

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