Skin is the biggest organ we have. As such, it often acts as a type of window into the rest of the body. So, rashes and other skin disorders can be a sign of something else going on inside of you — especially when you have cancer. That’s why it’s wise to pay attention when you notice one, and get it checked out if it doesn’t go away on its own.
Rashes and skin conditions that resemble rashes can be a symptom of some types of cancer. They can also be a side effect of the therapies used to treat cancer, or caused by other factors entirely, such as allergic reactions, shingles (herpes zoster), and other infections.
Investigation with your health care team will usually provide a clearer picture as to why you’ve developed a particular rash or skin condition. But it’s important to remember that not every disturbance on the skin is a rash. And not every skin rash is related to cancer.
Why the word ‘rash’ is so hard to define
Skin rashes are notoriously hard to define, as they can involve so many different features: itchiness, redness, bumpiness, roughness, scaliness, swelling, and irritation, to name but a few. But not every rash will share the same characteristics, and appearances can vary widely even between early cases and those that are more advanced.
At MD Anderson’s Leukemia Center, the skin conditions we see most often in our patients fall into one of three major categories.
Infections: This is one of the most common causes of skin rashes in leukemia patients. So, any time someone comes into the Leukemia Center with a new disruption of the skin barrier, infection is usually the first thing we think of. Whether it’s caused by a fungus, a bacterium or a virus, we work closely with our dermatology and infectious disease specialists to evaluate each patient. When needed, we also use biopsies to confirm the presence of a particular infection, then prescribe fungicidal, antibiotic or antiviral drugs to resolve those conditions.
Side effects: Also very common among our leukemia patients, these skin problems are caused by several families of drugs used in cancer treatment, including chemotherapy, targeted therapy and immunotherapy. Several new pill forms of chemotherapy in particular can cause unique skin breakdown syndromes. But rashes may also be an inflammatory reaction to more common drugs, such as antibiotics and antimicrobial agents. And skin problems related to cancer-treating agents run the gamut from mild to full-body, the latter of which can sometimes require hospitalization. The key to managing them is frequent communication between you and your care team, particularly when starting a new treatment regimen.
Leukemia cutis: One of the major skin disorders stemming directly from leukemia, these often bumpy growths arise from the blood cancer itself. They occur when neoplastic leukocytes (or white blood cells growing out of control) escape from their home base of blood or bone marrow and infiltrate the skin. Leukemia cutis is only seen in approximately 5% to 10% of our leukemia patients, so it’s not a common manifestation of the disease.
BPDCN:Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a form of acute leukemia that most commonly appears as skin lesions. It only affects about 500 to 1,000 Americans a year, so it’s extremely rare. But BPDCN has its own unique set of characteristics and treatment options, so it’s important to distinguish it from other leukemia subtypes early on.
Paraneoplastic syndromes: Paraneoplastic syndromes are caused by an unusual immune response to either a blood cancer, such as leukemia, or a solid tumor, such as breast cancer. Because of that, I tend to think of these as the intersection between inflammation and infection. One example is Sweet syndrome, which is also known as “acute febrile neutrophilic dermatosis.” Another is erythema nodosum, or an inflammation of the fatty layer in the skin. These can occur in both chronic and acute leukemia.
The rash that’s not really a rash: petechiae
Leukemia can impair the body’s ability to generate platelets, which makes repairing itself harder. As a result, tiny bruises may start to form in areas where blood naturally accumulates, such as the feet, legs, arms or hands. These bruises typically show up as collections of little red spots or dots just beneath the skin’s surface, a condition called “petechiae” (pronounced “puh-TEE-key-eye”).
Petechiae are generally caused by the breakdown of small blood vessels called capillaries near the skin’s surface. That makes it a circulatory issue, rather than a purely dermatological one. But it’s something seen fairly frequently in leukemia patients.
Most skin rashes are unrelated to cancer
The vast majority of leukemia patients who seek help for a new skin rash or eruption will either have an infection that’s unrelated to cancer or be experiencing a side effect of their medication(s). But if you develop a rash, don’t hesitate to ask your care team about it.
It’s also a good idea to examine your skin periodically, or ask a close friend or loved one to help you. Tell your doctor about any abnormal skin conditions or tissue breakdowns you might find. Your care team can determine what is causing them, and refer you to one of our dermatologists, if needed.