What are subcutaneous nodules?

The term "subcutaneous nodule" is a medical phrase that can basically cover any type of lump or bump that occurs under the skin. These bumps are noticeable and can be felt on the surface, but they are not skin blemishes themselves like warts and most moles. Many different things cause them to form, and while most are benign, some are signs of much more serious conditions. Medical experts generally advise people to keep an eye on any nodule they notice and get evaluated if it appears to be moving, changing size, or multiplying.

how they are formed

It is somewhat difficult to pin down exactly how or why nodules form, as they come in so many different varieties. They can appear anywhere on the body and in a wide range of sizes. They can be so small that they can hardly be felt, or large enough to be easily seen; they may be filled with fluid or a solid mass of cells or other tissue. Some nodules, such as abscesses, may spontaneously erupt and drain fluid, while others are nothing more than fat encapsulated under the skin. Some conditions, such as metastatic cancer, also cause nodules to appear, although in this case the lumps are just one of many more serious symptoms.

However, in all cases, the bumps form under the body's innermost layer of skin, known as the subcutaneous tissue. Skin has three main layers: the outer layer, or "epidermis," which actually has five layers of its own; the middle layer, or "dermis", which has two layers of its own; and the internal, subcutaneous level. Depending on what they're made of, they can be tender to the touch and often look red at first, and can appear almost anywhere on the body depending on what's causing them to grow.

Benign or harmless nodules

Bumps under the skin aren't usually considered normal, but they're not always harmful, either. Some insect bites can cause subcutaneous nodules, especially if the person bitten has an allergic reaction to toxins or other insect fluids. Most bites present as superficial bumps that go away within a few days, but when skin cells react poorly, fluid or irritation can also build up below the surface. Most of these will go away on their own after a week or so, but they should be watched to make sure they don't get infected or grow.

Some people are also genetically predisposed to benign subcutaneous nodules. These are generally considered harmless cosmetic defects, and most are made up of fat cells or other cellular matter. They may never go away, but they are rarely a problem. People who are concerned about them for cosmetic purposes can sometimes remove them surgically, but in some cases the removal may leave a more obvious mark than the nodule.

Cysts, which are usually harmless pockets of fluid, can also cause nodules. Ganglion cysts are some of the most common, usually occurring on the upper hand, foot, or wrist. Rheumatoid nodules can develop in people with rheumatoid arthritis, usually in or around joints that are inflamed.

More serious causes

However, nodules can also be a sign that something is more seriously wrong with a person's health, which is why many medical professionals recommend that people pay close attention to the lumps and bumps they see. Granulomas, for example, are a type of subcutaneous nodule caused by inflammatory disorders that can have a serious impact on the functioning of a person's internal organs. When tissues are irritated or inflamed, toxins and excess bacteria are often released into the blood, which can accumulate to form nodules under the skin.

Metabolic disorders such as hemochromatosis can also cause nodules to form and are a sign that a person is not allocating energy or blood sugar appropriately. In rarer cases, nodules can also be a symptom of metastatic cancer. When cancer is the cause, the lumps are often small tumors that, if left untreated, can spread cancerous tissue to the skin, blood, and nearby organs.

Self-diagnosis and care problems

People who notice subcutaneous nodules are often tempted to treat them themselves, although most medical experts advise against it. Topical creams designed for common bug bites and rashes usually can't penetrate to the lowest level of skin, and in some cases can cause more harm than good.

Piercing the nodule to drain it or relieve pressure can also be dangerous, as it is often very difficult to tell what it is made of. Draining a bacteria-filled nodule, for example, could actually spread an infection or worsen the underlying condition. People who aren't sure what to do are usually advised to take a "wait and see" approach to see if things go away on their own, and to carefully document their symptoms and reactions in the meantime.

When to seek help

Skin lumps that are painful, swollen, or tender to the touch, or that appear to be growing in size or number, usually should be evaluated by a skin specialist. Experts can often diagnose more serious conditions early on, and can stop many other problems before they start. Although most skin nodules are nothing to worry about, getting them checked out is a good way to rule out potential problems.

Common Treatment Options

How a dermatologist or other medical provider will treat a skin bump depends largely on what type of bump it is, as well as what caused it. Treatment may include antibiotics, anti-inflammatory medications, surgical drainage, or surgical removal.

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