The skin is the largest organ in the body and can often reveal signs of underlying health conditions, including blood cancers such as leukemia and lymphoma. According to The University of Texas MD Anderson Cancer Center, changes in the skin, rashes, or unusual lesions may sometimes be the first indications of these cancers. While many skin changes are harmless or caused by infections or medications, certain patterns may signal blood cancer. Recognising these symptoms early can lead to timely diagnosis and treatment, making awareness critical. Understanding which skin changes to monitor can help patients and caregivers seek medical attention before complications escalate.
Common skin symptoms of blood cancer
Blood cancers can produce visible skin symptoms including:

• Petechiae: Tiny red, brown, or purple spots caused by broken capillaries due to low platelet counts.
• Purpura: Larger blotchy bruises or discolourations that do not fade when pressed.
• Rashes: Patches on the skin that may be itchy or scaly.
• Easy bruising and bleeding due to impaired clotting is common.

These symptoms often result from blood abnormalities caused by leukemia or lymphoma rather than dermatological conditions alone.
Leukemia and skin signs
Sometimes, leukemia cells can leave the blood and bone marrow and settle in the skin. This is called leukemia cutis. When this happens, it can cause raised bumps, patches, nodules, or sores on the skin.
Another common sign of leukemia is petechiae, which are tiny red or purple spots that usually appear on the arms, legs, or torso. These spots don’t turn white when pressed, which helps distinguish them from ordinary rashes.
Other skin changes, such as larger bruises (purpura) or unusual rashes, may appear early in leukemia or indicate the disease is progressing. These happen because leukemia affects the blood, making it harder for the body to clot properly or fight infections.
Cutaneous T-cell lymphoma (CTCL) and other blood lymphomas
Blood cancers like CTCL, a type of skin lymphoma, can show up as dry, scaly, itchy patches or plaques. These often appear on parts of the body that don’t get much sun.
Other changes may include:

• Red, pink, brown, or grey patches
• Lumps or bumps that can sometimes break open
• Thickened skin on the palms or soles
• Hair loss in affected areas and swollen lymph nodes
• Widespread redness of the skin (erythroderma) in more advanced cases

These symptoms happen because lymphoma affects the immune system and the lymphatic system, which can cause the skin to react in these ways. Early recognition is important because these signs can easily be mistaken for eczema, infections, or other skin problems.
Petechiae: the “hidden” rash

• Petechiae are not a typical rash. They are tiny red or purple spots caused by small blood vessels (capillaries) breaking under the skin.
• They often appear on the feet, legs, arms, or hands
• They are caused by low platelet counts, a common effect of leukemia, which makes the blood less able to clot

Even though they may look like harmless spots, petechiae can be an early warning sign of blood cancer, so noticing them and checking with a doctor is important.
Blood cancers can present with noticeable skin symptoms such as petechiae, purpura, rashes, nodules, plaques, or itching. The type and severity vary depending on the blood cancer subtype and disease stage. Early recognition of these signs is crucial for timely diagnosis and treatment. Periodic skin examinations, awareness of unusual changes, and prompt consultation with a healthcare provider can improve outcomes. According to The University of Texas MD Anderson Cancer Center, understanding these symptoms and seeking medical attention without delay is an essential step in managing blood cancers effectively.