A Guide to Understanding: What are lesions found in the body?

October 1, 2025 •

5 min read

According to the National Cancer Institute, a lesion is defined as an area of abnormal or damaged tissue caused by injury, infection, or disease. This broad term can apply to any part of the body, so understanding what are lesions found in the body is vital for overall health awareness.

Quick Summary

Lesions are areas of abnormal tissue resulting from injury, infection, or disease. They can occur on the skin or internally, varying greatly in appearance and severity from benign to malignant. Diagnosis involves physical exams, imaging, and biopsies.

Key Points

Definition: A lesion is an area of abnormal or damaged tissue, a broad term encompassing growths, wounds, and spots caused by injury, infection, or disease.
Location: Lesions are not exclusive to the skin; they can form anywhere in the body, including organs like the brain, liver, and blood vessels.
Types: Skin lesions are classified as primary (e.g., moles, blisters) or secondary (e.g., ulcers, scars), depending on their origin and evolution.
Benign vs. Malignant: Lesions can be either non-cancerous (benign) or cancerous (malignant), with key differences in growth rate, invasiveness, and the potential to spread.
Causes: Causes range from common infections and environmental factors like sun exposure to systemic conditions like autoimmune disorders and internal cancers.
Diagnosis: Diagnosis involves physical examinations, patient history, and potentially advanced techniques like dermoscopy, biopsies, or medical imaging such as MRI and CT scans.
Medical Consultation: Any lesion that changes in size, shape, or color, or that is painful or bleeding, should be evaluated by a healthcare provider.

A lesion is a general term referring to any area of abnormal or damaged tissue. While most people associate the word with skin, lesions can form in virtually any part of the body, including vital organs like the brain and liver. They can manifest as growths, spots, bumps, or areas with a different color, shape, or texture from the surrounding tissue. Given their wide range of potential causes and implications, from harmless bug bites to serious cancers, understanding the different types, causes, and diagnostic approaches is crucial.

The Spectrum of Skin Lesions

Skin lesions are arguably the most common and visible type of lesion. They are typically categorized as primary or secondary. Primary lesions are the initial changes in previously healthy skin, while secondary lesions develop as a result of primary lesions progressing, being manipulated (e.g., scratching), or healing.

Primary Skin Lesions

Macules and Patches: Flat, discolored areas of skin. Macules are small (under 1 cm), like a freckle, while patches are larger.
Papules and Plaques: Raised bumps. Papules are small (under 1 cm), while plaques are larger, often flat-topped elevations associated with conditions like psoriasis.
Nodules and Tumors: Nodules are larger, deeper papules, and tumors are abnormal growths of cells that can be benign or malignant.
Vesicles and Bullae: Fluid-filled blisters. Vesicles are small (under 1 cm), often seen with herpes or chickenpox, while bullae are larger.
Pustules: Small, pus-filled lesions, such as those found in acne.
Wheals: Raised, itchy welts often associated with allergic reactions.

Secondary Skin Lesions

Ulcers: Open sores resulting from the loss of the epidermis and dermis.
Crusts: Dried serum or blood that forms scabs.
Scales: An accumulation of dead, flaky skin cells.
Scars: Raised or discolored tissue that forms during healing.

Common Causes of Lesions

The cause of a lesion can be a minor and localized issue or a symptom of a much larger, systemic problem.

Infections: Viral infections (herpes, HPV), bacterial infections (staph), and fungal infections can all cause lesions.
Autoimmune and Inflammatory Disorders: Conditions like psoriasis, lupus, and multiple sclerosis can cause lesions, in some cases affecting internal organs.
Cancer: Malignant tumors are a type of lesion, and internal cancers can also cause lesions to appear on the skin through metastatic spread or paraneoplastic syndromes.
Trauma and Injury: Cuts, burns, and head injuries can all result in lesions.
Environmental Factors: Unprotected sun exposure is a major risk factor for many skin lesions, including precancerous and cancerous growths.
Genetic Factors: Some lesions, such as certain moles or neurofibromas, are inherited.

Internal Lesions: The Hidden Abnormalities

Not all lesions are visible on the surface. Internal lesions, which affect organs or tissues within the body, are often discovered through imaging techniques like MRI or CT scans.

Brain Lesions

Damage to brain tissue can have a wide range of causes and symptoms depending on the location and size of the lesion.

Causes: These include traumatic brain injury, stroke (ischemic or hemorrhagic), multiple sclerosis (MS) which damages nerve sheaths, infections like encephalitis, and benign or malignant tumors.
Symptoms: Can range from subtle headaches and visual changes to severe seizures, paralysis, and cognitive or personality shifts.

Liver Lesions

Abnormal growths on the liver can be benign or malignant, and are often discovered incidentally during a scan.

Benign: Common types include hemangiomas (blood vessel growths), focal nodular hyperplasia (FNH), and hepatocellular adenoma. These often require no treatment but are monitored.
Malignant: Liver cancer (hepatocellular carcinoma) and metastatic cancer (spread from another organ) are examples. Causes include chronic hepatitis, cirrhosis, and obesity.

Benign vs. Malignant Lesions: A Critical Distinction

Understanding the difference between benign (non-cancerous) and malignant (cancerous) lesions is crucial for determining prognosis and treatment. A benign lesion consists of normal cells that grow in one place and do not spread, whereas a malignant one has abnormal cells that grow uncontrollably and can invade surrounding tissue or spread to other parts of the body (metastasize).


Feature	Benign Lesions	Malignant Lesions
Growth Rate	Typically slow	Often rapid and aggressive
Invasion	Do not invade nearby tissue	Can invade surrounding tissue
Spread (Metastasis)	Do not spread to other parts of the body	Can spread through the bloodstream or lymphatic system
Appearance	Often symmetrical with clear boundaries	Frequently asymmetrical with irregular borders and varied color
Recurrence	Unlikely to recur after removal	Higher chance of recurring, even in different locations
Cell Structure	Cells appear normal under a microscope	Cells have abnormal shape and chromosomes

Diagnosis and Treatment Options

The diagnostic process for any lesion begins with a thorough evaluation by a healthcare provider, which may involve a physical examination, review of medical history, and assessment of symptoms.

Diagnostic Techniques

Dermatoscopy: A non-invasive tool using magnification to examine skin lesions in detail.
Biopsy: For suspicious lesions, a small tissue sample is taken and analyzed in a lab (histopathology).
Imaging: For internal lesions, techniques such as MRI, CT scans, and ultrasounds are used to visualize the abnormality and provide more information.

Treatment Approaches

Treatment depends on the type, cause, and severity of the lesion. Some benign lesions may require no treatment, only monitoring.

Topical/Oral Medication: Used for infectious or inflammatory lesions (e.g., acne, psoriasis).
Cryotherapy: Freezing the lesion off, commonly used for warts and some precancerous growths.
Laser Therapy: Used for cosmetic removal, birthmarks, and some skin cancers.
Surgical Removal: Performed for suspicious, cancerous, or bothersome lesions. For internal lesions, surgery may involve more complex procedures.
Treating Underlying Conditions: For secondary lesions, addressing the root cause (e.g., managing an autoimmune disease) is necessary.

Conclusion: The Importance of Monitoring

Lesions are a common bodily occurrence, and while most are benign and harmless, their presence serves as a signal that something is different within the body. Whether a simple mole or a more complex internal growth, vigilance is key. It is essential to be aware of any changes in existing lesions or the appearance of new ones, particularly if they are growing, changing shape or color, or causing pain. Regular skin checks by a dermatologist, especially for those with risk factors like excessive sun exposure, can lead to early detection and treatment of serious issues. When in doubt, always consult a healthcare professional for a proper diagnosis and treatment plan to ensure your peace of mind and overall health.

For more detailed information on common skin lesions, visit the Cleveland Clinic's page on Skin Lesions.

Frequently Asked Questions

A lesion is a very general term for any abnormal tissue damage or growth. A tumor is a specific type of lesion that refers to an abnormal mass or lump of cells. Therefore, while all tumors are lesions, not all lesions are tumors.

While only a medical professional can provide a definitive diagnosis, you can use the ABCDE rule to monitor for signs of melanoma: Asymmetry, Border irregularity, Color variation, Diameter over 6mm, and Evolution (changes over time). Benign lesions are usually symmetrical, have smooth borders, and are uniform in color.

Stress does not directly cause brain lesions, but chronic stress can negatively impact brain health and function. It may exacerbate conditions that lead to brain injuries, such as high blood pressure and stroke.

No, not all lesions cause pain. Many benign lesions, such as lipomas or small moles, are painless. However, pain, itching, or tenderness can be a symptom, especially with inflammatory or infectious lesions, or with internal growths that press on nerves.

Internal lesions are typically discovered through medical imaging tests like MRI or CT scans, which may be ordered to investigate symptoms or found incidentally during tests for other conditions.

Many benign lesions are harmless and do not require treatment. However, they may be removed for cosmetic reasons, if they cause discomfort, or if there's a risk of them becoming malignant.

Common skin lesions include freckles (macules), pimples (pustules), blisters (vesicles), moles (nevi), warts, and skin tags. Some are inherited, while others are acquired through various factors.

While not all lesions are preventable, you can reduce your risk by using sunscreen to prevent sun damage, maintaining good hygiene to avoid infections, and managing underlying health conditions that might cause them.