Blood Blister Vs. Melanoma: How to Know the Difference

Medically Reviewed By Jenneh Rishe, RN

A blood blister is a small, raised pocket of blood under your skin. It typically occurs after an injury such as a pinch. Melanoma is a serious type of skin cancer that may initially resemble a blood blister. Blood blisters usually heal within 2 weeks, whereas melanoma is a serious condition that will continue to grow.

This article explains the differences and similarities between blood blisters and melanoma. It also discusses prevention, symptoms, treatment, and when to seek medical care.

What is a blood blister compared to melanoma?

A dermatologist examining a spot on a man's back
Urbazon/Getty Images

Blood blisters are harmless and heal on their own within a week or two. Melanoma, however, is a cancerous spot on your skin.

Some melanoma subtypes, such as nodular melanoma, may initially resemble a blood blister. However, they will not go away within 2 weeks. Melanoma can also spread to other parts of the body and requires intensive medical treatment.

What is a blood blister?

A picture of a red blood blister on a person's palm
A blood blister is a blood-filled lesion that is typically red, purple, or black. They usually develop on the skin after a pinching or friction injury and generally heal within a few weeks. Image via Healthgrades

A blood blister is a small, painful, raised area under your skin that is filled with blood. They typically appear red, purple, or black. Blood blisters form as a protective layer after blood vessels are damaged from pinching or high-pressure friction.

What is nodular melanoma?

A black melanoma lesion on a person's skin
Nodular melanoma lesions can be black, red, or blue-black. They commonly form on sun-exposed skin and can grow quickly over weeks to months. Unlike blood blisters, they do not heal and will require cancer treatment. Photo credit: Nasekomoe/Shutterstock

Nodular melanoma is the second most common type of melanoma, accounting for 15–30% Trusted Source PubMed Central Highly respected database from the National Institutes of Health Go to source of all cases.

With nodular melanomas, a lump forms quickly over several weeks or months and extends deep into the skin. They are typically larger than most moles and may itch, sting, or bleed.

Nodular melanomas commonly occur in exposed areas such as your head or neck. Lumps may appear dome-shaped and can be black, red, or blue-black in color. The area may feel smooth, rough, or crusty.

Learn more about the warning signs of melanoma.

The cause of nodular melanoma is unknown. It is common in people with lighter skin tones but can also occur in people with darker skin.

Other risk factors for nodular melanoma include:

  • excessive sun exposure
  • increasing age
  • previous melanoma history
  • numerous moles or atypical moles

Learn more about nodular melanoma.

When should you see a doctor about a blood blister?

Blood blisters due to a minor injury, such as pinching your finger, may not require medical care. Seek medical care for signs of infection or if your blood blister:

  • feels hot or looks redder than the surrounding skin
  • contains green or yellow pus
  • is located in your mouth, eyelid, or genital area
  • occurs from a burn or allergic reaction
  • is recurring
  • turns into several blisters

How can a doctor tell if it is a blood blister or melanoma?

Your dermatologist will perform a thorough examination of your blister or lump and the surrounding skin. This will help them confirm a diagnosis and rule out potential melanoma.

Identifying blood blisters

To identify a blood blister, your doctor will assess the area and ask about your:

  • medical history
  • symptoms
  • recent injuries
  • activities that may have caused a blood blister

Diagnosing melanoma

If your doctor suspects melanoma, you may need further testing. This may include blood and imaging tests such as:

They may also need to remove a small piece of the lump tissue through a biopsy for further examination in a lab.

Learn more about how doctors diagnose skin cancer.

How do you treat blood blisters?

According to the American Academy of Dermatology Association, it is best to leave a blister alone. Most blisters heal in 1–2 weeks. Try to avoid popping or draining the blister, which could cause infection.

While your blister heals, cover it loosely with a bandage. If it is located in a pressure area, such as the bottom of your foot, cut a hole in some padding to place around the blister. Then, cover it with a bandage.

If you have a large, painful blood blister, contact your doctor. They may recommend draining your blister to reduce discomfort.

Learn more about how to treat your blood blister.

How do you treat melanoma?

Treatment for melanoma depends on the stage of your cancer, and how deep the tumor extends. You may need one or more treatments or a combination of treatments.

Treatment for melanoma may include:

  • Excision: This is surgery to cut out the cancer along with some surrounding skin.
  • Mohs surgery: This procedure removes cancer but attempts to leave more of the surrounding skin.
  • Lymph node dissection: This removes the lymph nodes in the region near the primary melanoma tumor.
  • Radiation therapy: This is often a follow-up treatment after surgery. It aims to target any remaining cancer cells or stop new cells from forming.
  • Chemotherapy: Chemotherapy drugs target cancer cells.
  • Targeted therapy: This involves medications that target cancer cells and can temporarily shrink cancer.
  • Immunotherapy: Immunotherapy involves medication received intravenously (IV) that helps your immune system recognize and target cancer cells.

How do you prevent blood blisters and melanoma?

Since blood blisters occur because of injury, there is sometimes no way to prevent them. However, it can help to discontinue the activity that is causing your blister, such as wearing different shoes.

Melanoma prevention 

One of the best ways to prevent melanoma is to protect your skin from harmful UV rays. You can do this by:

  • limiting time spent in the sun
  • staying in shady areas when outdoors
  • avoiding the use of tanning beds
  • wearing a hat
  • applying sunscreen to exposed areas of your skin

The American Cancer Society Trusted Source American Cancer Society Highly respected international organization Go to source recommends using sunscreen with broad-spectrum protection and an SPF of at least 30.

It is also important to perform regular skin checks.

Other frequently asked questions

Here are a few other common questions about blood blisters and melanoma. These answers were reviewed by Jenneh Rishe, RN.

How serious is nodular melanoma?

Nodular melanoma is more aggressive and grows faster than other types of melanoma.

One study compared the 5-year survival rate of patients with nodular melanoma to those with superficial-spreading melanoma. It found that survival rates were lower in patients with nodular melanoma.

What does a blood blister look like?

A blood blister appears as a red or purple bump under your skin. As it heals, it may become dark red or black.

Summary

A blood blister is a small pocket of blood under your skin and is usually harmless. It can sometimes resemble nodular melanoma, a cancerous lump that grows quickly over the course of weeks or months.

To diagnose a blood blister, your medical professional will examine the lump. They will also ask about your medical history, activities, and any recent injuries. Diagnosing melanoma may require testing, such as a biopsy, imaging study, or blood test.

A blood blister typically does not need treatment other than covering it to prevent further damage. Treatment for melanoma will depend on the stage of your cancer and how deep it has grown. This may include surgery, radiation, or medications.

If you are concerned a blood blister may be melanoma, contact your doctor for a diagnosis.

Was this helpful?
22

Medical Reviewer: Jenneh Rishe, RN
Last Review Date: 2022 Nov 19
View All Melanoma Articles
THIS TOOL DOES NOT PROVIDE MEDICAL ADVICE. It is intended for informational purposes only. It is not a substitute for professional medical advice, diagnosis or treatment. Never ignore professional medical advice in seeking treatment because of something you have read on the site. If you think you may have a medical emergency, immediately call your doctor or dial 911.