3. Unusual Lumps, Skin Changes, or Changes in Sensation
A third category of changes involves the skin, underlying tissues, and nerves of the arms and legs. Certain cancers can produce a new lump, a growing area of thickening, an unusual skin lesion, or persistent changes in sensation.
These symptoms have many possible explanations, but some patterns deserve closer attention.
A new lump beneath the skin
Soft-tissue sarcomas are uncommon cancers that develop in tissues such as muscle, fat, nerves, blood vessels, and connective tissue. They can occur in almost any part of the body, including the arms and legs.
One possible early sign is a lump beneath the skin. It may initially be painless and easy to overlook, particularly when it develops deep within a muscle.
As the mass grows, it may become more visible or begin pressing against nearby structures. Depending on its location, a person might notice tightness, discomfort, reduced movement, or changes in sensation.
Not every lump is a sign of cancer. Lipomas, cysts, hematomas, and other benign growths are much more common. Nevertheless, a lump that continues to enlarge, feels deep within the tissues, or measures several centimeters across should be assessed by a healthcare professional.
A growing lump should not be repeatedly squeezed, punctured, or treated with unverified home remedies in an attempt to make it disappear.
Changes in the skin or nails
The skin can sometimes provide clues about underlying health problems, although most skin changes are not cancer-related.
For example, melanoma, a potentially serious form of skin cancer, can develop on an arm, leg, hand, foot, or beneath a nail. It may appear as a new dark spot or as a change in an existing mole.
A useful approach is to pay attention to the ABCDE warning signs of melanoma:
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A β Asymmetry: One half of a spot looks different from the other.
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B β Border: The edges are irregular, blurred, or uneven.
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C β Color: The spot contains multiple colors or develops an unusual color change.
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D β Diameter: The spot is larger than approximately 6 millimeters, although melanoma can be smaller.
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E β Evolving: The spot changes in size, shape, color, elevation, or appearance over time.
A new or changing lesion should be assessed by a clinician, especially if it bleeds, does not heal, or looks noticeably different from other spots on the skin.
Dark discoloration beneath a fingernail or toenail can have several causes, including trauma, infection, or benign pigmentation. However, a new dark streak or patch that does not grow out with the nail, particularly when it widens or changes, deserves medical evaluation to rule out nail-unit melanoma.
It is important not to assume that every unusual nail color indicates cancer. A photograph alone cannot establish a diagnosis, and changes should be interpreted alongside the person's history and physical examination.
Numbness, tingling, or unexplained weakness
Nerves carry signals between the brain, spinal cord, and the rest of the body. When a nerve is compressed, irritated, or damaged, a person may experience numbness, tingling, burning sensations, or weakness in an arm or leg.
These symptoms are frequently caused by noncancerous conditions such as carpal tunnel syndrome, a slipped disc, diabetes-related nerve damage, or vitamin deficiencies.
In some cases, however, a tumor can press against a peripheral nerve or affect structures near the spinal cord. Certain cancers can also cause nerve-related symptoms through inflammation, treatment complications, or other mechanisms.
Symptoms may include persistent tingling in the fingers or toes, reduced sensation in part of a limb, difficulty gripping objects, or weakness that interferes with walking.