Patient Education
Dermatology Glossary
Clear, patient-friendly explanations of common terms related to skin conditions, diagnosis, procedures, medicines, cosmetic care, and lasers.
A
- Acne
- A common skin condition in which hair follicles become blocked by oil and dead skin cells, producing blackheads, whiteheads, pimples, or deeper lesions.
- Actinic keratosis
- A rough, scaly area caused by cumulative ultraviolet exposure. Some actinic keratoses can develop into squamous cell carcinoma, so evaluation is important.
- Allergen
- A normally harmless substance that triggers an immune response in a person with an allergy, such as pollen, a food, medication, or contact ingredient.
- Atopic dermatitis
- A chronic, relapsing form of eczema that causes dry, itchy, inflamed skin and is associated with changes in the skin barrier and immune system.
B
- Basal cell carcinoma
- The most common type of skin cancer. It usually grows slowly and rarely spreads to distant sites, but untreated tumors can damage nearby tissue.
- Benign
- Not cancerous. A benign growth does not invade surrounding tissue or spread to distant parts of the body, although it may still warrant treatment.
- Biopsy
- Removal of a small sample of skin or other tissue so it can be examined under a microscope to help establish a diagnosis.
- Botulinum toxin
- A prescription injectable medicine that temporarily reduces targeted muscle activity. In dermatology it may be used for facial lines or certain medical conditions.
C
- Chemical peel
- A controlled application of a chemical solution that removes selected outer layers of skin to address concerns such as texture, pigment, acne, or sun damage.
- Cherry angioma
- A common, benign growth made of small blood vessels that typically appears as a bright red or purple spot on the skin.
- Contact dermatitis
- An itchy or inflamed rash caused either by direct irritation or by an allergic reaction after the skin contacts a substance.
- Cryotherapy
- Treatment that uses intense cold, often liquid nitrogen, to destroy selected abnormal or unwanted tissue.
- Cyst
- A closed sac beneath or within the skin that may contain fluid, keratin, or other material. Skin cysts are often benign but can become inflamed.
D
- Dermal filler
- An injectable gel placed beneath the skin to restore volume, soften selected folds, or refine contours. Products and longevity vary.
- Dermatitis
- A general term for inflammation of the skin, often involving redness, itching, scaling, swelling, or discomfort.
- Dermis
- The supportive layer of skin beneath the epidermis. It contains collagen, elastin, blood vessels, nerves, hair follicles, and glands.
- Dysplastic nevus
- An atypical mole with clinical or microscopic features that differ from an ordinary mole. Having atypical moles can be associated with increased melanoma risk.
E
- Eczema
- A broad group of inflammatory skin conditions that can cause itching, dryness, redness, scaling, oozing, or thickened skin.
- Epidermis
- The outermost layer of skin, which forms a protective barrier and contains pigment-producing melanocytes.
- Excision
- Surgical removal of a lesion with a margin of surrounding tissue, followed by closure of the wound when appropriate.
F
- Folliculitis
- Inflammation of hair follicles, often appearing as clusters of small red or pus-filled bumps. Causes include infection, irritation, or blocked follicles.
H
- Hyperpigmentation
- Darkening of an area of skin due to increased melanin. It may follow inflammation, sun exposure, hormonal changes, or other causes.
- Hives (urticaria)
- Raised, itchy welts that can change shape and location over hours. Hives may be triggered by infection, medication, foods, or other factors, but often have no clear cause.
K
- Keloid
- A raised scar that grows beyond the boundaries of the original injury because of excess collagen production.
L
- Laser resurfacing
- Use of focused light energy to create controlled skin injury and remodeling, which may improve selected scars, lines, texture, or pigment concerns.
M
- Melanin
- Pigment produced by melanocytes that contributes to skin, hair, and eye color and helps absorb ultraviolet radiation.
- Melanoma
- A potentially serious cancer of melanocytes. Early detection is important because melanoma can spread to other parts of the body.
- Melasma
- A condition causing symmetrical brown or gray-brown patches, most often on the face. Sun exposure and hormonal factors can contribute.
- Microneedling
- A procedure using fine sterile needles to create controlled microchannels in the skin and stimulate a healing response.
- Mohs surgery
- A specialized skin cancer surgery performed in stages. Each layer is examined microscopically until no cancer remains, helping preserve healthy tissue.
- Mole (nevus)
- A usually benign growth made of pigment-producing cells. New or changing moles should be assessed when they show concerning features.
P
- Patch testing
- A test in which small amounts of potential contact allergens are applied to the back under patches and checked later for delayed allergic reactions.
- Photodynamic therapy (PDT)
- Treatment combining a light-sensitive medication with a specific light source to target selected abnormal or damaged cells.
- Psoriasis
- A chronic immune-mediated disease that speeds skin-cell turnover, commonly producing well-defined, scaly plaques and sometimes affecting joints.
R
- Rosacea
- A chronic facial skin condition that may cause persistent redness, flushing, visible blood vessels, acne-like bumps, or eye symptoms.
S
- Seborrheic dermatitis
- A common inflammatory condition causing flaky or greasy scale, often on the scalp, eyebrows, ears, or central face.
- Skin tag
- A soft, benign growth that often forms where skin rubs against skin or clothing.
- Squamous cell carcinoma
- A common skin cancer arising from squamous cells. It can grow deeply and occasionally spread, especially when high-risk or untreated.
T
- Telangiectasia
- A small, widened blood vessel visible near the skin surface, often appearing as a fine red line.
- Topical medicine
- A medication applied directly to the skin, such as a cream, ointment, gel, lotion, foam, or solution.
U
- Ultraviolet (UV) radiation
- Invisible energy from the sun and artificial sources such as tanning beds. UVA and UVB can damage skin and contribute to premature aging and skin cancer.
V
- Vitiligo
- An autoimmune condition in which melanocytes are lost, leading to sharply defined areas of depigmented skin.
W
- Wart
- A benign skin growth caused by infection with certain types of human papillomavirus (HPV). Warts can spread through direct or indirect contact.
Authoritative sources
Definitions were researched and paraphrased from patient education and cancer terminology maintained by the following medical organizations. Individual linked service pages provide additional practice-specific context.