Does skin cancer have pus? A complete medical guide

We are a dermatologist in Delray Beach, Florida.

Being that we’re located in sunny Florida, we see a lot of skin cancer patients.

One question we get is if skin cancer produces pus.

In this guide, we’ll walk you through the details.

Introduction

When patients notice a new or changing spot on their skin, one of the most common questions they ask is: could this be cancer? A frequent source of confusion is when a lesion produces fluid, drainage, or pus. People are used to seeing pus with infections like acne or cysts, but it can be frightening when something that looks like an infection does not heal.

This article answers the question, does skin cancer have pus? The short answer is that cancer itself does not directly produce pus, but skin cancers can ulcerate, bleed, and become secondarily infected, which may result in pus-like drainage. We will break this down in detail, review medical research, and help you understand when to see a dermatologist.

What Is Pus?

Pus is a thick fluid made up of white blood cells, bacteria, and tissue debris. It forms when the body mounts an immune response against infection. Common causes of pus on the skin include acne, abscesses, and infected cysts.

Skin cancer, on the other hand, is caused by the uncontrolled growth of abnormal cells. Because cancer is not an infection, it does not naturally create pus. However, once a tumor breaks the skin barrier or ulcerates, bacteria can enter, leading to secondary infection. That is when pus may appear.

The Three Main Types of Skin Cancer

1. Basal Cell Carcinoma (BCC)

• The most common type of skin cancer.

• Appears as pearly bumps, open sores, or shiny pink patches.

• Grows slowly but can cause local tissue damage.

2. Squamous Cell Carcinoma (SCC)

• Appears as scaly patches, warty growths, or sores that may crust or bleed.

• Can spread to lymph nodes if untreated.

3. Melanoma

• The most dangerous type.

• Often looks like an irregular or changing mole.

• Can spread rapidly and become life-threatening.

Each of these cancers can ulcerate and sometimes drain, but pus is usually only present if bacteria infect the lesion.

Can Skin Cancer Produce Pus on Its Own?

Skin cancer cells do not secrete pus. Instead, two scenarios explain why pus may appear:

1. Secondary infection. A tumor breaks the skin, bacteria colonize the wound, and pus forms.

2. Tissue death (necrosis). Advanced cancers can damage surrounding tissue, leaving areas that may resemble pus.

A study in the Journal of the American Academy of Dermatology examined malignant ulcers and found that bacterial colonization was extremely common. Researchers noted that infection can change the appearance of a cancerous lesion, making it look more like a boil or abscess. For patients, this means that if a sore produces pus, it should not automatically be assumed to be “just an infection.”

How Infections and Cancers Overlap

The National Cancer Institute explains that one hallmark warning sign of skin cancer is a wound that does not heal. Unfortunately, infections and cancers can share similar symptoms:

• Redness and swelling

• Drainage of fluid or pus

• Crusting or scabbing

• Pain or tenderness

The key difference is that infections usually improve with antibiotics, while cancers persist or return.

A British Journal of Dermatology study followed patients who were originally treated for “chronic skin infections.” Researchers discovered that many of these cases were actually undiagnosed cancers. Because treatment was delayed, the lesions grew larger and more complicated. The takeaway is clear: if a lesion that looks infected does not respond to standard treatment, it should be evaluated for skin cancer.

Basal Cell Carcinoma and Pus

Basal cell carcinoma is not known for producing pus, but it can present as an open sore that bleeds or crusts. When these ulcers are present for a long time, bacteria may settle in the area, leading to infection and pus formation.

The American Cancer Society notes that basal cell carcinoma often appears as a sore that heals and then returns. If pus develops in such a lesion, it may be due to a superimposed infection, not the cancer itself.

Squamous Cell Carcinoma and Pus

Squamous cell carcinoma is somewhat more likely to produce discharge. Lesions often crust, bleed, and develop central ulcers. These ulcers can become infected.

A study published in the Journal of Cutaneous Pathology looked at squamous cell carcinomas that had ulcerated and found that bacterial infection was present in a significant percentage of cases. Patients often presented thinking they had chronic “infected wounds” rather than cancer. The study highlights why persistent pus-draining sores should always be biopsied.

Melanoma and Pus

Melanomas typically do not produce pus. Instead, they may ooze clear fluid or blood. However, ulcerated melanomas can become infected.

A study in The Lancet Oncology examined ulcerated melanomas and found that ulceration is associated with a poorer prognosis. Infections complicate healing and may mask the true nature of the lesion. For patients, any mole that bleeds, drains, or looks different from the rest should be checked promptly.

What the Research Shows About Infections in Skin Cancer

Several key studies shed light on the relationship between infection and cancerous wounds:

1. Malignant ulcers frequently colonized by bacteria. The JAAD study found that infections are common in malignant ulcers and can complicate both appearance and management.

2. Misdiagnosis delays treatment. The BJD study revealed that many cancers are mistaken for chronic infections, causing dangerous delays.

3. Ulcerated melanomas carry worse outcomes. The Lancet Oncology analysis showed that ulceration, often accompanied by infection, predicts poorer survival rates.

4. Biopsy remains essential. A systematic review in JAMA Dermatology concluded that despite advanced imaging, biopsy is still the gold standard to distinguish infection from malignancy.

5. Non-healing wounds often malignant. A study in Acta Dermato-Venereologica confirmed that many chronic ulcers initially thought to be “infected wounds” were actually squamous cell carcinomas.

6. Skin cancer and wound bacteria linked to delayed healing. Research in the International Wound Journal found that bacterial infection in malignant wounds increases pain, odor, and drainage, complicating treatment.

Together, these studies show that pus in a skin lesion is often a sign of infection on top of cancer, not cancer alone.

How Dermatologists Diagnose the Difference

If a patient presents with a pus-producing lesion, dermatologists take a stepwise approach:

1. History. How long has the lesion been present? Has it responded to antibiotics?

2. Exam. Is the lesion irregular, growing, or changing color?

3. Dermatoscopy. Special magnification may reveal cancer-specific patterns.

4. Biopsy. A small tissue sample provides the definitive answer.

Biopsy is particularly important when pus or drainage is present, because infection can obscure the true diagnosis.

Treatment Approaches

Treatment depends on the cancer type:

• Basal cell carcinoma. Excision, Mohs surgery, topical medications.

• Squamous cell carcinoma. Excision, Mohs surgery, radiation therapy in select cases.

• Melanoma. Wide excision, lymph node biopsy, systemic therapy if advanced.

When infection is present, dermatologists may prescribe antibiotics or recommend wound care while also addressing the cancer itself.

Living With a Cancerous Lesion That Drains

Patients with ulcerated or infected cancers often need special wound care:

• Clean gently with mild soap and water.

• Use non-stick dressings.

• Monitor for foul odor or spreading redness.

• Avoid self-treating with harsh chemicals or over-the-counter creams.

Dermatologists provide personalized wound care plans to minimize infection while preparing for definitive cancer treatment.

Prevention and Early Detection

Preventing complications starts with early detection:

• Perform monthly skin checks.

• See a dermatologist yearly for a professional exam.

• Protect skin with sunscreen and clothing.

• Avoid tanning beds.

The Skin Cancer Foundation emphasizes that early treatment reduces the chance of ulceration, infection, and scarring.

Frequently Asked Questions

• Does skin cancer itself ooze pus?

  No, cancer cells do not make pus. Pus usually means there is an infection in or around the cancer.

• Can a mole get infected and produce pus?

  Yes, but if a mole changes in appearance, ulcerates, or produces drainage, it should always be evaluated for cancer.

• How can I tell if a sore is infected or cancerous?

  Infections often improve with antibiotics, while cancers persist or recur. A biopsy is the only way to know for sure.

• Does pus mean cancer is advanced?

  Not always, but ulcerated or infected cancers are usually more serious. Ulceration in melanoma, for example, is linked with worse outcomes.

• If antibiotics clear the pus, is the problem solved?

  Not necessarily. Even if infection resolves, the underlying lesion may still be cancer.

Conclusion

Skin cancer does not directly create pus, but when lesions ulcerate and bacteria invade, pus can appear. Research confirms that infections are common in malignant ulcers and can confuse both patients and doctors. The safest approach is to treat any non-healing, draining sore as suspicious until proven otherwise.

At Barnett Dermatology, we stress that patients should not wait to see if a “pus-producing sore” gets better on its own. Biopsy and early diagnosis are the keys to effective treatment and prevention of complications.