Skin Lesions: Symptoms, Types, Causes & Care
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Introduction
A skin lesion is an area that differs from the skin around it 3,5. It may look like a bump, rash, sore, blister, growth, or unusual color 1,3.
Skin lesions are common and may result from injury or skin damage 5. They can also point to an infection, immune disease, or another health condition 5.
Many skin lesions are benign, which means they are not cancerous 5. However, some lesions may be precancerous or cancerous 4,5.
Understanding skin lesion symptoms, types, causes and when to seek care can guide safe choices. This guide covers common changes, warning signs, diagnosis, treatment, and skin monitoring.
Overview: What Is a Skin Lesion?
Definition and common features
A skin lesion is any area that looks different from nearby skin 3,5. The difference may involve color, shape, texture, height, or overall appearance 5.
Lesions can appear anywhere on the body 5. The location and pattern may help a clinician assess the possible cause 5.
Some lesions are present at birth, including certain moles and birthmarks 5. Others develop later because of injury, infection, allergy, disease, or sun damage 5.
A lesion may be flat, raised, solid, open, crusted, or filled with fluid 5. Some lesions cause pain or itching, while others cause no clear symptoms 5,6.
Primary versus secondary skin lesions
Clinicians often divide the types of skin lesions into primary and secondary groups 5. Primary lesions are initial skin changes, rather than changes from scratching or healing 5.
Primary skin lesions include these common forms:
A macule or patch is a flat mark with a different color 5.
A papule or plaque is a raised, pimple-like area 5.
A nodule is a raised, solid bump 5.
A vesicle or bulla is a blister filled with fluid or blood 5.
A pustule is a raised spot filled with pus or white fluid 5.
A cyst is a raised sac that extends below the skin 5.
Secondary lesions develop after a primary lesion changes or becomes irritated 5,6. Scratching or another direct injury can cause these later changes 5,6.
The main secondary skin lesions include the following forms:
A crust is dried fluid around a wound 5.
A scale is an area of flaky or peeling skin 5.
An erosion is a worn or broken surface area 5.
A fissure is a painful crack in the skin 5.
An ulcer is an open sore 5.
A scar is changed tissue left after healing 5.
Atrophy means the skin has become thin and wrinkled 5.
Benign, precancerous, and cancerous lesions
Benign lesions are not cancerous and are often harmless 5. They may not need treatment unless they cause discomfort or appearance concerns 5.
Actinic keratosis is one example of a premalignant skin lesion 4. Premalignant means that abnormal cell changes are present before cancer develops.
Malignant lesions are cancerous skin growths 5. Common categories include basal cell carcinoma, squamous cell carcinoma, and melanoma 2,4.
A visual examination may not provide a final answer. A biopsy can show whether a suspicious lesion contains cancer cells 1,4.
Symptoms and Types of Skin Lesions
Changes in color, shape, texture, and size
Skin lesion symptoms differ based on the lesion and its cause 5. Possible symptoms include an unusual growth, itching, swelling, pain, or color change 5.
Color changes may appear red, brown, black, or blue 5. Some skin diseases can look different across skin tones 6.
Psoriasis may look red and silver on lighter skin 6. On darker skin, it may appear gray, purple, or brown with lighter scales 6.
Flat lesions include macules and patches 5. Raised lesions include papules, plaques, nodules, pustules, and cysts 5.
The surface may become scaly, crusted, cracked, or open 5. Lesions may also change in size, shape, or color over time 5.
Growth, shape changes, bleeding, pus, or poor healing deserve medical assessment 5. These changes do not identify the cause by themselves.
Itching, pain, swelling, and drainage
Itching occurs with several skin conditions. Allergic eczema can cause itchy, scaly, raw skin 6.
Eczema may also cause blisters that ooze or form crusts 6. Contact dermatitis appears after the skin touches an allergen or irritating substance 6.
Psoriasis causes defined patches with scales 6. These patches may itch, but some cause no symptoms 6.
Pain may occur with inflamed bumps, sores, cysts, or infections. Acne can cause deep, painful cysts and nodules 6.
Fluid-filled lesions may leak before forming a crust. Cold sores release clear yellow fluid before they crust 6.
Pustules contain pus or white fluid 5. A resistant staph infection may cause a painful, raised spot that drains pus 6.
Increasing redness, swelling, pain, or drainage can signal infection after a skin biopsy 1. Fever may also occur when a biopsy wound becomes infected 1.
Examples of common lesion types
Many familiar skin problems fall under the broad skin lesion category. Their features may overlap, so appearance alone may not identify the cause.
Common examples of skin lesions include the following conditions:
Acne may cause blackheads, whiteheads, pimples, papules, nodules, or cysts 5,6.
Allergic eczema can cause itchy, scaly, raw, blistered, or crusted skin 6.
Psoriasis may cause sharply defined patches with scales 6.
Warts are lesions that clinicians may treat with cryotherapy 3.
Moles are pigmented lesions, and some are present at birth 5.
Epidermoid cysts are slow-growing, noncancerous lumps filled with keratin 6.
Birthmarks are primary lesions that may be present at birth 5.
Insect bites may appear as primary or allergic skin lesions 5.
Sunburn is a skin lesion caused by injury from sun exposure 5.
Actinic keratosis may appear as a thick, scaly, or crusted patch 6.
Lichen planus is another condition that causes skin lesions. It can produce purple, shiny, flat bumps that itch 8.
The disease may also affect the mouth, genitals, nails, hair, or scalp 8. A clinician should assess unexplained bumps or rashes without a known cause 8.
Causes and Risk Factors
Injuries, allergies, and infections
Skin lesion causes include injuries such as sunburns and wounds 5. Damage can create a new lesion or change an existing one 5,6.
Allergic reactions may follow contact with poison ivy or another allergen 5. Insect bites can also cause allergic skin lesions 5.
Contact dermatitis appears where the skin touches the substance that caused it 6. It may cause itching, scales, raw skin, blisters, or crusting 6.
Some medicines can cause skin lesions as a side effect 5. Pain relievers and other medicines may activate lichen planus 8.
Viral, bacterial, and fungal infections can affect the skin 1,5. Each group can produce different skin lesion symptoms and types.
Herpes simplex viruses cause cold sores and genital lesions 6. Cold sores are painful, fluid-filled blisters that often appear near the lips 6.
Impetigo causes blisters that break easily and form honey-colored crusts 6. It often affects skin near the mouth, chin, and nose 6.
Inflammatory and underlying conditions
Autoimmune diseases may cause lesions when the immune system attacks body tissues 5. Psoriasis is linked with skin lesions that can return over time 5.
Lichen planus may involve an immune attack against skin or mucous membrane cells 8. Mucous membranes line areas such as the mouth and genitals.
The exact cause of lichen planus remains unclear 8. The condition is not contagious 8.
Poor circulation can contribute to skin lesions 5. Liver disease, kidney disease, cancer, and immune disorders may also cause skin changes 5.
A clinician may consider these problems when assessing a lesion. Fever, joint pain, swelling, or other concerns also support medical evaluation 5.
Acne develops when bacteria, dead skin cells, and oil form lesions 5. It often affects the face, chest, and back 5.
Sun exposure and skin cancer risk factors
Ultraviolet radiation is a main cause of skin cancer 4. It raises risk for basal cell carcinoma, squamous cell carcinoma, and melanoma 2,4.
Skin sensitivity and the pattern of ultraviolet exposure may affect skin cancer risk 2. Fair-skinned people with sun exposure have a higher melanoma risk 2.
Genes and immune function also play roles in skin cancer development 2,4. Some unusual moles and having many moles are linked with greater melanoma risk 2.
Organ transplant recipients often take medicines that suppress the immune system. These recipients have increased skin cancer risk, especially for squamous cell carcinoma 2.
Most melanomas in the general population may start as new lesions 2. One review found more new melanomas than melanomas linked to existing moles 2.
Therefore, attention should not focus only on existing moles. A new growth can also be a possible skin cancer sign 5.
Sunscreen use and reduced ultraviolet exposure are key prevention steps 4. These steps do not replace an assessment of a suspicious growth.
When to See a Doctor
Warning signs that need an appointment
Arrange an evaluation for a new growth or changing mole 5. A wound that does not heal also needs medical assessment 5.
These changes can be signs of skin cancer 5. However, a clinician may need a biopsy to determine the cause 1,4.
A lesion also needs assessment if it grows or changes shape 5. Severe pain, bleeding, pus, fever, or poor healing also need medical care 5.
Seek an appointment for unexplained bumps or a rash without a known cause 8. Prompt diagnosis matters because several conditions can cause painful sores 8.
Important skin lesion warning signs include the following changes:
A new growth appears without a known cause 5.
An existing growth or mole begins to change 5.
A wound does not heal as expected 5.
A lesion increases in size or changes shape 5.
A lesion causes severe pain, bleeding, or pus drainage 5.
A rash appears with fever, joint pain, or swelling 5.
Signs that may suggest skin cancer
Skin cancer may appear as a new growth 5. It may also appear as a changing mole or nonhealing wound 5.
Basal cell carcinoma, squamous cell carcinoma, and melanoma can have different clinical features 4. A biopsy may be needed to identify the specific cancer type 4.
An unusual lesion is not always cancer. Skin growths may be benign, premalignant, or malignant 4.
Most melanomas may develop as new spots rather than from existing moles 2. Watch for both new lesions and changes in spots already present.
Signs of a possible skin infection
Worsening redness, swelling, or pain may signal infection after a skin biopsy 1. Thick drainage or fever can also indicate an infected biopsy site 1.
Pus may look tan, green, or yellow and may smell bad 1. Contact the treating clinician if these signs develop after a biopsy 1.
A resistant staph infection may resemble a painful, raised pimple with pus 6. It can lead to cellulitis or a blood infection 6.
These possible infection signs require prompt medical care:
Redness, swelling, or pain worsens near a biopsy wound 1.
Thick yellow, green, or tan drainage appears around the wound 1.
Drainage smells bad or appears to contain pus 1.
Fever occurs with an inflamed or draining lesion 1,5.
A painful, raised bump starts draining pus 6.
The sources support prompt clinician contact for these infection signs 1,5. They do not provide broad emergency instructions for these symptoms.
Diagnosis, Treatment, and Skin Monitoring
How healthcare professionals assess lesions
A clinician may consider a lesion’s size, location, type, and symptoms 1,3. These features help guide the next diagnostic step 1,3.
Testing may identify bacteria, fungus, psoriasis, immune disease, or skin cancer 1. Some tests examine skin under a microscope 1.
Visual skin examination is the only widely proposed screening method for skin cancer 2. It includes self-exams and clinical exams by healthcare professionals 2.
Evidence does not show that population screening lowers skin cancer deaths in symptom-free adults 2. Screening can also lead to overdiagnosis, false findings, or procedure-related harm 2.
This evidence concerns broad screening among people without symptoms. New, changing, painful, or nonhealing lesions still need individual medical assessment 5.
When a skin biopsy may be needed
A skin biopsy removes a small sample for examination under a microscope 1. It can help diagnose a rash or check a lesion for cancer 1.
Biopsy results may identify dermatitis, psoriasis, bacterial infection, or fungal infection 1. They may also identify melanoma, basal cell carcinoma, or squamous cell carcinoma 1.
The clinician chooses a method based on the lesion’s type, size, and location 1. The suspected diagnosis also guides that choice 1,7.
The main skin biopsy methods include these procedures:
A shave biopsy scrapes or removes the outer skin layers 1.
A punch biopsy removes a small sample that includes deeper layers 1,7.
An incisional biopsy removes part of a large lesion 1.
An excisional biopsy removes the whole lesion and may include deeper tissue 1.
An excisional biopsy is often used when melanoma is suspected 1.
A clinician numbs the area before removing the skin sample 1,7. Punch and excisional biopsies may require stitches 1,7.
Biopsy risks include bleeding, infection, mild pain, and scarring 1,7. The healthcare team provides wound-care instructions after the procedure 1,7.
Treatment and Ongoing Care
Treatment options
Treatment depends on the diagnosis and the lesion’s features 3,4. Some benign lesions need no treatment unless they cause discomfort or appearance concerns 5.
Treatment may include observation, skin medicines, or medicines that work throughout the body 4. Skin cancer care may also involve radiation or a procedure 4.
Common procedures for selected skin lesions include these options:
Cryotherapy freezes selected tissue to destroy it 3.
Clinicians may use cryotherapy for warts and actinic keratoses 3.
Laser treatment uses focused light to treat specific tissue 3.
Curettage uses a tool to scrape or scoop out a lesion 3.
Full excision removes a lesion through deeper skin layers 3.
Mohs surgery removes certain cancers while sparing nearby healthy skin 3.
A removed lesion is often sent to a laboratory for microscopic examination 3. The procedure choice depends on the lesion’s size, type, and location 3.
Safe self-monitoring
Self-examination is one form of visual skin assessment 2. It does not provide the tissue testing available through a biopsy 1,2.
Photos may create a visual record for later comparison. However, consumer skin apps have uncertain accuracy for detecting skin cancer 2.
These apps have not been tested in large population screening programs 2. They should not replace an examination by a trained healthcare professional 1,2.
A clinician should assess a new, changing, painful, bleeding, or nonhealing lesion 5. A biopsy may be needed when the cause remains unclear 1.
Conclusion
Understanding skin lesion symptoms, types, causes and when to seek care supports informed choices. Lesions may include bumps, rashes, sores, blisters, growths, or unusual skin colors 1,3.
Many skin lesions are benign 5. Others may reflect infection, immune disease, precancerous change, or cancer 1,4,5.
A new growth, changing mole, or nonhealing wound needs professional evaluation 5. Worsening pain, swelling, redness, pus, or fever also requires prompt medical care 1,5.
Clinical examination and biopsy can identify many skin conditions 1. Photos and apps may aid tracking, but they cannot replace professional assessment 1,2.
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