When people hear “skin cancer,” they’re probably reminded of the common forms like basal cell and squamous cell carcinoma or the more serious but still relatively common melanoma. However, there are other less common forms of skin cancer that may look nothing like what a patient may expect. According to Dr. Neil Vigil of U.S. Dermatology Partners at the North Valley Dermatology office in Peoria, AZ, “A Merkel cell carcinoma doesn’t look like a melanoma. Cutaneous T-cell lymphoma (CTCL) can look like eczema for years, leading to misdiagnosis and delayed treatment. As a dermatologist, my job is to make sure patients know what changes are worth a call, because when we act early, we can almost always do something about it.” In this blog, Dr. Vigil discusses rare skin cancers and their warning signs.
Why Not All Skin Cancers Look the Same
Most people think of skin cancer as dark, irregularly shaped moles or lesions. That’s a fair description of many melanomas, but rarer forms of skin cancer have unique appearances and growth patterns that aren’t expected. While irregular coloring, uneven borders, and crusted or non-healing sores are common in most types of cancers, other typical symptoms like rapid growth don’t always occur with rarer skin cancers. These less common forms of skin cancer typically develop deeper within skin’s layers and can affect immune cells, neuroendocrine cells, or connective tissues. Because the damage caused by these cancers doesn’t originate in the visible, outer layers of skin, the symptoms are more subtle and may take longer to appear.
When it comes to the warning signs of rare forms of skin cancer, Dr. Vigil says, “Rarer skin cancers often don’t fit the expected mold, so they’re easily overlooked. Be aware of warning signs like rapid growth, unexplained bleeding, and sores that don’t heal. In general, any new or changing growths on skin that seem irregular should be evaluated by a professional so we can act earlier or provide some reassurance and peace of mind.” Rare skin cancers can show up as:
- Smooth, shiny lumps.
- Persistent rash-like patches that mimic common eczema.
- Thickened patches of skin (plaques).
- Skin that looks and feels like scar tissue without prior injury.
- Lesions that easily bleed.
- Sores that don’t heal or recur after healing.
- Firm bumps beneath skin that continue to increase in size.
Rare Types of Skin Cancers
There are several rare types of skin cancers but the following three skin cancers are important for patients to be aware of because they can mimic normal skin growths.
Merkel Cell Carcinoma
Merkel cell carcinoma is a very aggressive form of skin cancer that can grow rapidly. It develops in specialized neuroendocrine cells that are involved in touch sensation. This skin cancer gained more public attention when American singer-songwriter Jimmy Buffett passed away after a tough four-year battle with Merkel cell carcinoma. It is most common on parts of the body that receive frequent sun exposure, especially the head and neck of older adults or people with compromised immune systems.
The danger of Merkel cell carcinoma is how ordinary it can look. These tumors are often painless bumps on the scalp, often with patients thinking they have a new cyst. The best way to recognize this condition and intervene early is to perform regular self-checks, so you notice right away if a growth develops or changes rapidly.
Early diagnosis is essential to effectively treat Merkel cell carcinoma, so it’s important to contact a dermatologist if you notice any of the common warning signs of this condition, including:
- A new bump that appears and grows quickly.
- A firm, dome shaped nodule (deep bump).
- Red, pink, or violet coloring.
- A lump that doesn’t hurt. Painless is not reassurance.
Cutaneous T-Cell Lymphoma
Cutaneous T-cell lymphoma (CTCL) is a rare cancer of immune cells (T-cells) that shows up in the skin. Unlike Merkel cell carcinoma, it usually develops slowly over years. It is a master of disguise, truly a rash that is a skin cancer. Early on it is often misdiagnosed and treated as eczema or psoriasis with dry itchy patches of skin that come and go. As the disease develops, it can vary in appearance and symptoms. Even to the trained eye, these conditions can be mistaken for more benign skin conditions.
“This is the one that fools everyone, including physicians,” Dr. Vigil says. “The tipoff is a ‘rash’ that never fully responds to treatment. If we’ve treated stubborn eczema that keeps worsening, especially in areas covered by a bathing suit, that needs a biopsy.” Sometimes multiple biopsies are required to diagnose cutaneous T-cell lymphoma. This type of skin cancer may show a range of characteristics, including:
- Persistent rash-like patches of skin, often on areas that get little sun.
- Dry, scaly skin.
- Patches of eczema that slowly thicken into raised areas of skin.
- Itchy or irritated skin.
- Slowly expanding, irregular skin discoloration.
Dermatofibrosarcoma Protuberans (DFSP)
Dermatofibrosarcoma protuberans (DFSP) is a form of skin cancer that starts beneath the top layer of skin in the connective tissue. It grows slowly, but can spread to surrounding tissues when untreated. The slow growth of DFSP means it may take years for symptoms to advance to the point where patients seek treatment. The cancerous region may appear like birthmarks, scar tissue, or thickened patches of skin. DFSP generally develops on the upper arms, chest, shoulders, and trunk. This skin cancer can also affect children and young adults. Have a growth evaluated if it shows:
- Firm, thickened skin that feels like scar tissue with no injury to explain it.
- Slow but steady growth over months to years
- Brown or red coloring or flesh-toned growth.
- Raised or rubbery lump
Warning Signs That Shouldn’t Be Ignored
According to Dr. Vigil, “Knowing the warning signs of skin cancer usually means checking skin for the ABCDEs. That’s how dermatologists refer to the five main symptoms of skin cancer: asymmetry, border irregularity, color irregularity, diameter larger than a pencil eraser, and evolving. If you have a new or changing spot that fits any of those characteristics, it shouldn’t be ignored. What about rare cancers? They may not show the same symptoms.” Below, Dr. Vigil outlines the five symptoms that mean your dermatologist should examine your skin:
- Rapid growth – any spot that’s growing or changing quickly may indicate skin cancer. Regular skin cells replicate at a predictable rate. Cancer cells don’t, so if you notice rapid growth or change, the risk for skin cancer is greater, especially cancers like Merkel cell carcinoma.
- Firm bumps – cancerous tumors tend to feel different from benign lumps and bumps. Most notably, they are typically hard, and they don’t move freely. Some protrude, others can only be felt with pressure.
- A rash that won’t clear – most rashes clear up or improve within a few weeks of treatment. When there’s no improvement with treatment, a rash may be a warning sign of something more serious, especially when it spreads to surrounding areas or coincides with thickened areas of skin.
- Bleeding lesions – a spot that bleeds on its own or with light contact, crusts over repeatedly, or ulcerates into an open sore needs evaluation.
- Any changing growth – change in size, shape, texture, or color is the single most reliable red flag across every type of skin cancer, common or rare.
Importance of Early Detection and Biopsy
When it comes to early detection and skin cancer biopsy, Dr. Vigil says, “Even the most serious skin cancers respond better when we catch them early. The problem is that some skin cancers look and feel harmless, so patients wait. By the time an aggressive cancer like Merkel cell carcinoma is diagnosed, it may have already spread. Early evaluation is the whole ballgame.”
Catching these cancers early means treatment can be more effective, less invasive, and far more likely to result in full recovery. Because skin cancer can resemble benign conditions, the eye alone is often not enough. That’s where a biopsy comes in. This is a quick in-office procedure that involves removing a small amount of tissue and examining it under a microscope. Biopsies can tell dermatologists if cancer is present, what type of cancer, and how severe.
When to See a Dermatologist
Visiting a dermatologist is important anytime unusual skin cancer symptoms appear. Any new or changing skin findings should be looked at. Those who have a personal or family history of skin cancer should be especially dedicated to checking for signs of cancer and working with a dermatologist. Some patients should be especially proactive, including those with a history of severe sunburns, frequent or prolonged sun exposure, or weakened immune system. If that’s you, do a head-to-toe self-check monthly and see a dermatologist yearly. Sooner if anything changes. Dr. Vigil recommends adults living in Arizona, especially over 30 years old, should see a dermatologist yearly for a full body skin cancer screening. Specifically, anyone should seek dermatologic intervention in the following situations:
- Quickly changing or growing lesions.
- Rashes that don’t improve with standard care options.
- Lesions that bleed or are painful.
- Firm bumps beneath or protruding from skin.
- Thickened areas of skin that aren’t responsive to treatment.
Frequent Skin Cancer Exams Lead to Earlier Intervention
In summary, Dr. Vigil says, “Whether it’s a common basal cell carcinoma or a rarer condition most people have never heard of, the formula is the same. Early diagnosis leads to better outcomes. Check your skin regularly, and if needed, come in once a year for a professional exam. Don’t sit on a spot that’s changing.”
Schedule Your Annual Skin Cancer Screening
When you’re ready for your annual skin cancer screening, take a few moments to complete our online scheduling request form. These routine exams ensure a professional evaluates any concerning skin conditions, but it’s also important to reach out right away if you notice any of the traditional and less common symptoms of skin cancer discussed in this blog.
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