Can Folliculitis Decalvans Scars Turn Into Skin Cancer?

Squamous cell skin cancer (SCC) developing in long-standing Quinquaud folliculitis decalvans (FD) scars has been reported in the medical literature, but it is uncommon ^[1]. The true risk of this happening has not been quantified, and there are only a small number of published cases ^[1]. However, because skin cancer can sometimes occur in areas of chronic inflammation and scarring, it is important to know which skin changes require prompt medical assessment rather than assuming every change is just another FD flare ^[2].

Why Cancer Can Form in Scar Tissue

Skin that has been inflamed or scarred for many years—often decades—can undergo changes that increase the risk of malignant (cancerous) cells developing. When a squamous cell carcinoma develops in an area of long-standing scarring or a chronic wound, doctors sometimes use the historical term Marjolin ulcer.

In people with scarring hair-loss conditions like FD, prolonged inflammation, long-term exposure of the bare scalp to ultraviolet (UV) rays, and the use of certain immunosuppressive medications are proposed as general risk factors for skin cancer in scars ^[2]. However, evidence directly linking these factors to SCC specifically in FD is limited ^[2]. Having FD does not mean you will inevitably get skin cancer ^[1]. You should continue any prescribed immunosuppressive treatments unless your doctor tells you to stop.

Distinguishing Normal FD from Warning Signs

Quinquaud folliculitis decalvans is known for causing cycles of scalp inflammation. Most pustules, crusting, and tenderness in FD are simply inflammatory ^[3]. Typical symptoms of an FD flare include recurrent pus-filled bumps (pustules), redness, crusting, tufts of hair, itching, and pain ^[4].

Because these symptoms are expected, spotting a new problem requires looking for changes that are distinctly different from your usual pattern. Contact your dermatologist within a few days if you notice:

• A persistent or enlarging discrete lump: A new, firm mass that continues to grow rather than resolving like a typical pustule ^[5][6].
• A sore that won’t heal: A persistent open wound (ulceration) that does not heal over several weeks ^[5][7].
• Unusual bleeding or hemorrhagic crusting: A spot that bleeds easily or forms unusual, bloody crusts ^[6][8].
• Exophytic tissue: Fleshy growths that stick out from the skin surface ^[6][8].
• Escalating or deep localized pain: A sudden change in the type or intensity of pain, or a lump that feels deeply tender or fixed to the tissue below ^[5].

Note: Some of these signs, such as foul-smelling drainage, crusting, and increased pain, can also happen with a bacterial infection or a severe FD flare ^[8]. Seeing these warning signs does not mean you definitely have cancer, but they do require a medical evaluation to be sure.

When to seek urgent care: If you experience uncontrolled bleeding, rapidly spreading swelling, fever, or feel acutely unwell, seek urgent medical care immediately.

What to Do If You Spot a Warning Sign

If you notice any of these signs, do not rely only on your routine FD treatments, and do not delay an examination. Do not start applying new medications to cover the lesion, and ask your prescribing clinician whether to continue your current medicines until your exam ^[9].

Because SCC and FD inflammation can look similar or happen at the same time, a visual exam alone is not always enough ^[10]. To confirm a diagnosis, your doctor will likely perform a skin biopsy, removing a small sample of the tissue (usually under local anesthetic) to be examined under a microscope ^[9].

The dermatologist will choose the biopsy method (such as a shave, punch, or surgical excision) based on the lesion’s appearance ^[11]. Sometimes, deeper samples are needed to assess abnormal cells hidden in the scar ^[12][13]. If a spot continues to look suspicious but an initial biopsy does not show cancer, your doctor may recommend a repeat biopsy or removing the lesion entirely ^[10].

Monitoring Your Scalp

Because SCC in FD is so uncommon, there is no established, FD-specific screening schedule for skin cancer. Follow-up frequency depends on your specific symptoms, the duration of your FD, your UV exposure, and other personal risk factors.

Between appointments, check accessible areas of your scalp periodically. You can use photographs or ask a trusted person to inspect hard-to-see areas. To protect your scarred scalp from UV damage, wear a protective hat and use broad-spectrum sunscreen on intact skin; avoid putting sunscreen on open or actively draining wounds unless advised by your doctor ^[2].