What are lesions, and what kinds do doctors look for?

What are lesions, and what kinds do doctors look for?

A lesion is any abnormal change in the structure of an organ or tissue, caused by injury, infection, inflammation or disease. Lesions can be visible on the skin or detected inside the body through imaging and lab tests. Understanding what lesions are and how they’re classified helps you recognize when to seek medical advice.

Definition and basics
A lesion is simply an area of tissue that has been altered from its normal state. This alteration can be:

• A change in size (for example, a lump or swelling)
• A change in color (such as a red or dark spot)
• A change in texture (for example, scaly or ulcerated skin)
• A loss of function (for example, weakened brain tissue on imaging)

Doctors assess lesions based on where they occur, how they present and what underlying process is likely responsible. Most lesions fall into broad categories that guide further testing and treatment.

Common types of skin and soft-tissue lesions
Skin lesions are perhaps the easiest to spot. They come in many shapes and sizes, and dermatologists classify them by appearance:

• Macule – a flat spot, like a freckle or flat mole (e.g., a red spot on the arm)
• Papule – a small, raised bump less than 1 cm across (e.g., a wart)
• Nodule – a larger, deeper bump over 1 cm (e.g., a lipoma)
• Vesicle – a fluid-filled blister under 1 cm (e.g., chickenpox blister)
• Bulla – a larger fluid-filled blister over 1 cm (e.g., second-degree burn blister)
• Pustule – a pus-filled lesion (e.g., a whitehead or acne pustule)
• Ulcer – a loss of skin surface, often with a crater-like appearance (e.g., a pressure sore)

Each lesion type suggests different causes—viral, bacterial, inflammatory or neoplastic (tumor-related).

Internal lesions: what imaging reveals
Lesions inside the body require tools like ultrasound, CT, MRI or X-rays. Common examples include:

• Liver lesions: cysts (fluid-filled), hemangiomas (benign blood-vessel growths) or tumors (benign or malignant)
• Lung nodules: small round spots on a chest X-ray or CT scan; can be scars, infections or early cancers
• Brain lesions: areas of abnormal tissue on MRI, which may represent stroke, multiple sclerosis plaques or tumors
• Bone lesions: focal areas of bone destruction (lytic) or excess formation (sclerotic) seen on X-ray, suggesting infection, benign growths or cancer

Doctors look at size, shape, borders and growth over time to determine whether an internal lesion is harmless or needs a biopsy.

Benign versus malignant lesions
One of the most important distinctions is whether a lesion is benign (non-cancerous) or malignant (cancerous). Features that raise concern for malignancy include:

• Rapid growth
• Irregular or poorly defined borders
• Mixed colors (e.g., dark brown, black, red in a mole)
• Ulceration or bleeding
• Location in high-risk organs (brain, liver, lungs)

Benign lesions tend to grow slowly, have smooth borders and remain uniform in color or texture.

How doctors evaluate lesions
When you notice a lesion—on your skin or through symptoms like unexplained pain—your doctor will:

1. Take a focused history
   • Onset and duration
   • Associated symptoms (itching, bleeding, neurological changes)
   • Personal or family history of similar lesions or cancers
2. Perform a physical exam
   • Inspect and measure any visible lesion
   • Check for nearby lymph node enlargement
   • Assess function (for example, neurological exam if a brain lesion is suspected)
3. Order diagnostic tests
   • Dermatoscopy or skin biopsy for suspicious skin lesions
   • Blood tests (e.g., liver function, tumor markers)
   • Imaging (ultrasound, CT, MRI, PET scan) to characterize internal lesions
4. Refer as needed
   • Dermatologist for complex skin lesions
   • Oncologist if cancer is suspected
   • Neurologist or neurosurgeon for brain lesions

Common causes of lesions by category
• Infectious lesions
– Bacterial (e.g., impetigo, abscess)
– Viral (e.g., herpes zoster vesicles)
– Fungal (e.g., athlete’s foot scales)

• Inflammatory lesions
– Eczema or psoriasis plaques
– Autoimmune ulcers (e.g., in inflammatory bowel disease)

• Traumatic lesions
– Cuts, bruises, abrasions, pressure sores

• Neoplastic lesions
– Benign growths (e.g., lipomas, moles)
– Pre-cancerous changes (dysplasia)
– Malignant tumors (e.g., melanoma, carcinoma, sarcoma)

When to seek medical advice
Most skin lesions are harmless, but you should see a doctor if you notice:

• New or changing mole or spot on your skin
• Ulcer or sore that doesn’t heal in 2–4 weeks
• Persistent pain, bleeding or discharge from any lesion
• Signs of infection (redness, warmth, swelling, fever)
• Unexplained lumps or bumps inside your body (palpable or found on imaging)

For non-urgent concerns, you might start with a free, online symptom check, using the doctor approved Ubie Symptom Checker. This tool can help you understand possible causes and decide when to see a physician.

Preventing and monitoring lesions
• Skin protection
– Apply broad-spectrum sunscreen daily
– Wear protective clothing and hats outdoors
• Regular self-exams
– Monthly skin checks for new or changing spots
– Breast or testicular self-exams as recommended
• Routine health screenings
– Mammograms, colonoscopies and other age-appropriate tests
– Follow-up imaging for any known internal lesions as advised

Early detection of worrisome lesions often leads to better outcomes.

Treatment options
Treatment depends on the lesion type and underlying cause:
• Topical therapies
– Steroid creams for inflammatory lesions
– Antifungals or antibiotics for infections
• Surgical removal
– Excision of suspicious moles or skin cancers
– Drainage of abscesses
• Minimally invasive procedures
– Cryotherapy (freezing) for warts or precancerous spots
– Laser therapy for certain skin growths
• Systemic treatments
– Chemotherapy, immunotherapy or targeted therapy for malignant tumors
– Antiviral or antibiotic medications for infections

Your doctor will tailor the approach based on risks and benefits.

Key takeaways

• Lesions are any abnormal areas of tissue change.
• They can appear on the skin or inside organs.
• Classification by appearance, cause and benign versus malignant status guides evaluation.
• Most lesions are harmless, but changes in size, shape or function warrant medical review.
• You can begin with a free, online symptom check, using the doctor approved Ubie Symptom Checker to gauge urgency.

If you have any lesion that concerns you—especially one that bleeds, grows rapidly or causes persistent pain—speak to a doctor. Life-threatening or serious conditions require prompt medical attention.