Dermatological Glossary (A to Z)

Dr. Lazuk Esthetics® Dermatological Glossary (A–Z)

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A

Ablative laser – A laser that removes targeted tissue to resurface skin and soften wrinkles or scars; requires downtime as new skin forms.

Category: Procedure / Laser

See also: Non‑ablative laser; Fractional CO2; Er:YAG; Resurfacing

Acne – Inflammation of the pilosebaceous unit causing comedones, papules, pustules, nodules or cysts. Triggers include genetics and hormones.

Category: Condition

See also: Comedone; Retinoid; Benzoyl peroxide; Isotretinoin

Acne scars – Texture/color changes after acne heals; atrophic (ice‑pick, boxcar, rolling) or hypertrophic/keloidal.

Category: Condition / Sequelae

See also: Microneedling; TCA CROSS; Fractional laser; PRP

Actinic keratosis – Rough, scaly precancer from chronic sun exposure; small risk of SCC if untreated.

Category: Condition / Precancer

See also: Cryotherapy; Field therapy; Sunscreen

Adapalene – Topical retinoid for acne; normalizes cell turnover and reduces inflammation with relatively low irritation.

Category: Medication / Topical

See also: Retinoid; Tretinoin; Retinaldehyde

Allergic contact dermatitis – Itchy eczematous rash due to delayed hypersensitivity to an allergen after sensitization.

Category: Condition / Inflammatory

See also: Patch testing; Irritant contact dermatitis

Alpha hydroxy acids (AHAs) – Water‑soluble exfoliants (glycolic, lactic) that smooth texture and brighten tone; used in peels and skincare.

Category: Ingredient / Exfoliant

See also: Glycolic acid; Lactic acid; BHA; Chemical peel

Alopecia – General term for hair loss: androgenetic, areata, telogen effluvium, scarring forms.

Category: Condition / Hair

See also: Androgenetic alopecia; Minoxidil; PRP

Androgenetic alopecia – Pattern hair loss driven by genetics/androgens; managed with minoxidil, finasteride (men), LLLT, PRP.

Category: Condition / Hair

See also: Alopecia; Minoxidil; Finasteride; PRP

Angioma (Cherry) – Benign red vascular papule from dilated capillaries; removable with cautery or laser.

Category: Lesion / Vascular

See also: Telangiectasia; Hemangioma; Pulsed‑dye laser

Atopic dermatitis (eczema) – Chronic, itchy, inflammatory dermatitis with barrier dysfunction and type‑2 inflammation.

Category: Condition / Inflammatory

See also: Emollient; Topical steroid; Calcineurin inhibitor; Dupilumab

Atypical mole (dysplastic nevus) – Nevus with irregular features; marker of higher melanoma risk; surveillance advised.

Category: Lesion / Pigmented

See also: Melanoma; Dermoscopy; ABCDE B —

B

Bacne – Acne on the back; treat with benzoyl peroxide washes, retinoids; rule out yeast folliculitis.

Category: Condition (Colloquial)

See also: Truncal acne; Malassezia folliculitis

Barrier (skin barrier) – Stratum corneum + lipids preventing water loss/irritant entry; supported by ceramides, humectants, pH‑balanced care.

Category: Concept / Physiology

See also: Ceramides; TEWL; Humectant

Basal cell carcinoma (BCC) – Most common skin cancer; pearly papule or non‑healing sore; treated with surgery, Mohs, topicals.

Category: Condition / Cancer

See also: Mohs surgery; SCC; Sunscreen

Benzoyl peroxide – Topical antimicrobial/comedolytic that reduces C. acnes and antibiotic resistance; can bleach fabrics.

Category: Ingredient / OTC

See also: Acne; Retinoid; Clindamycin

Beta hydroxy acid (BHA) – Oil‑soluble exfoliant—salicylic acid—that penetrates pores to reduce congestion/inflammation.

Category: Ingredient / Exfoliant

See also: Salicylic acid; AHA; Acne

Biostimulator (filler) – Injectables (e.g., poly‑L‑lactic acid, CaHA) that stimulate collagen for gradual volume/quality gains.

Category: Procedure / Injectable

See also: Hyaluronic acid filler; Collagen; PRF/PRP

Blackhead (open comedone) – Clogged pore with oxidized keratin/sebum creating dark surface color.

Category: Lesion / Acne

See also: Comedone; Retinoid; Salicylic acid

Bulla – Fluid‑filled blister >5 mm; causes include friction, burns, autoimmune disease, infection.

Category: Morphology

See also: Vesicle; Erosion; Blistering disorders C —

C

Candela™ laser hair removal – Brand family (e.g., GentleMax Pro) using specific wavelengths with dynamic cooling for hair reduction.

Category: Procedure / Laser

See also: Laser hair removal; Fitzpatrick skin type; DCD

Carcinoma in situ – Early cancer confined to epidermis (e.g., SCC in situ/Bowen); treated with excision or topical/photo therapies.

Category: Condition / Cancer

See also: SCC; Actinic keratosis; Mohs

Cellulite – Dimpling from fibrous septae, fat herniation, and laxity; treat with mechanical, laser, RF options; results vary.

Category: Condition / Cosmetic

See also: Endospheres; RF microneedling; Collagen

Chemical peel – Controlled acids (glycolic, salicylic, TCA) to exfoliate/resurface; depth: superficial/medium/deep.

Category: Procedure

See also: AHA; BHA; TCA CROSS; Post‑peel care

Chloasma (melasma) – Hormone/UV‑triggered facial hyperpigmentation; requires sun protection and depigmenting agents.

Category: Condition / Pigment

See also: Melasma; Hydroquinone; Tranexamic acid

Cicatrix (scar) – Fibrous tissue replacing normal skin after injury; types: atrophic, hypertrophic, keloid.

Category: Concept / Wound healing

See also: Keloid; Microneedling; Laser

Cleanser (facial) – pH‑balanced product that removes impurities without stripping barrier.

Category: Product Category

See also: Surfactant; Micellar water; Double cleanse

Comedone – Clogged follicle of keratin/sebum; opens (blackhead) or closed (whitehead).

Category: Lesion / Acne

See also: Blackhead; Whitehead; Retinoid

Contact dermatitis (irritant) – Non‑immune irritation caused by harsh substances; burning/stinging > itch.

Category: Condition / Inflammatory

See also: Allergic contact dermatitis; Barrier repair

Contact dermatitis (allergic) – Immune‑mediated dermatitis from specific allergens; avoid trigger; consider patch testing.

Category: Condition / Inflammatory

See also: Fragrance mix; Nickel; Patch testing

Cryotherapy – Liquid nitrogen freezing to destroy benign lesions or precancers (AK).

Category: Procedure / Destructive

See also: Actinic keratosis; Wart; Seborrheic keratosis

Cyst – Sac‑like lesion with keratin or fluid; EIC has central punctum; excision definitive.

Category: Lesion

See also: Epidermal inclusion cyst; Milia D —

D

Dermatitis – Inflammation of skin; umbrella term (atopic, seborrheic, contact, nummular, stasis).

Category: Condition / Inflammatory

See also: Eczema; Seborrheic dermatitis; Contact dermatitis

Dermatofibroma – Firm, dimple‑sign papule (often on legs) representing benign fibrohistiocytic lesion.

Category: Lesion / Benign

See also: Histiocytoma; Shave biopsy

Dermatographism – Wheal/flare after scratching due to mast cell release; a physical urticaria.

Category: Condition / Urticaria

See also: Urticaria; Antihistamine

Dermatology – Medical specialty of skin, hair, nails (medical, surgical, cosmetic).

Category: Field / Specialty

See also: Dermatologist; Trichology; Nail disorders

Dermatoscopy (Dermoscopy) – Magnified, polarized evaluation of lesions for cancer diagnosis and patterns.

Category: Tool / Diagnostic

See also: ABCDE; Melanoma; Benign nevus

Dermatomyositis – Autoimmune disease with heliotrope rash, Gottron papules, and muscle weakness.

Category: Condition / Autoimmune

See also: Polymyositis; Myositis; Malignancy screening

Dermatophyte – Fungi that infect keratinized tissues (skin, hair, nails).

Category: Microbiology

See also: Tinea; Onychomycosis

Desquamation – Shedding of stratum corneum cells; accelerated by exfoliants or disease.

Category: Concept / Physiology

See also: Exfoliation; AHA; BHA E —

E

Eczema – Common term for atopic dermatitis—itchy, chronic inflammatory rash with barrier dysfunction.

Category: Condition / Inflammatory

See also: Atopic dermatitis; Emollient

Ehlers‑Danlos syndrome (EDS) – Connective tissue disorders with hyperextensible skin and joint laxity.

Category: Condition / Genetic

See also: Cutis laxa; Elastin

Elastin – Protein that provides stretch/recoil; declines with age/UV.

Category: Concept / Structural protein

See also: Collagen; Photoaging

Emollient – Moisturizer that softens/soothes by occlusion and lipid support.

Category: Product Category

See also: Humectant; Occlusive; Moisturizer

Epidermis – Outermost skin layer of keratinocytes in strata; barrier/protection.

Category: Anatomy

See also: Dermis; Stratum corneum

Epidermolysis bullosa – Inherited blistering disorders with skin fragility.

Category: Condition / Genetic

See also: Bulla; Vesicle; Wound care

Erysipelas – Superficial bacterial skin infection with raised, well‑demarcated erythema (often face/legs).

Category: Condition / Infectious

See also: Cellulitis; Streptococcus

Erythema multiforme – Immune‑mediated target lesions often triggered by infections (HSV).

Category: Condition / Immune

See also: Target lesions; Stevens‑Johnson syndrome F —

F

FAAD – Fellow of the American Academy of Dermatology—board‑certified dermatologist membership.

Category: Professional / Credential

See also: Dermatologist; Board‑certified

Fitzpatrick skin type – I–VI phototype scale guiding UV counseling and laser settings.

Category: Scale / Phototype

See also: Photoaging; Sunscreen; Laser

Folliculitis – Inflamed/infected hair follicles causing pustules/papules.

Category: Condition / Infectious

See also: Staphylococcus; Malassezia; Acne

Fractional laser – Energy in micro‑columns to induce controlled injury/healing with less downtime.

Category: Procedure / Laser

See also: Ablative; Non‑ablative; Resurfacing

Furuncle (boil) – Deep folliculitis/abscess, often due to Staph aureus.

Category: Condition / Infectious

See also: Carbuncle; I&D; Antibiotics

Fungal acne (Malassezia folliculitis) – Yeast‑related folliculitis with monomorphic papules/pustules; responds to antifungals.

Category: Condition / Infectious

See also: Folliculitis; Antifungal; Dandruff shampoos G —

G

Glogau scale – Photoaging classification I–IV based on wrinkles/solar damage.

Category: Scale / Aging

See also: Fitzpatrick type; Photoaging

Glycolic acid – Smallest AHA; exfoliates, brightens; used in skincare and peels.

Category: Ingredient / AHA

See also: AHA; Chemical peel

Granulation tissue – New connective tissue and capillaries in wound healing.

Category: Concept / Wound healing

See also: Epithelialization; Scar

Granuloma annulare – Benign ring‑shaped dermal papules, often on hands/feet; may self‑resolve.

Category: Condition

See also: Sarcoidosis; Nummular dermatitis

Guttate psoriasis – Droplet‑like papules post‑strep infection; often responsive to phototherapy.

Category: Condition / Inflammatory

See also: Psoriasis; NB‑UVB H —

H

Hair follicle – Structure producing hair with bulb, papilla, and sebaceous gland.

Category: Anatomy / Hair

See also: Sebaceous gland; Follicular unit

Hemangioma – Benign vascular tumor; infantile type proliferates then involutes.

Category: Lesion / Vascular

See also: Angioma; Vascular laser

Herpes zoster (shingles) – Reactivation of varicella‑zoster virus causing painful dermatomal vesicles.

Category: Condition / Infectious

See also: Postherpetic neuralgia; Antivirals

Hidradenitis suppurativa – Chronic inflammatory disease with nodules/abscesses/sinus tracts in folds; scarring.

Category: Condition / Inflammatory

See also: Acne inversa; Biologics

Hirsutism – Excess terminal hair in androgen‑dependent areas in women; assess endocrine causes.

Category: Finding / Hair

See also: PCOS; Androgens; Laser hair removal

Hyperhidrosis – Excessive sweating (focal/generalized); managed with topicals, devices, neuromodulators.

Category: Condition

See also: Aluminum chloride; Iontophoresis; Botox

Hyperkeratosis – Thickened stratum corneum; occurs in calluses and many dermatoses.

Category: Finding

See also: Keratoderma; Psoriasis I —

I

Ichthyosis – Group of disorders with dry, scaly skin due to abnormal keratinization.

Category: Condition / Genetic

See also: X‑linked ichthyosis; Emollients; Keratolytics

Impetigo – Contagious superficial bacterial infection with honey‑colored crusts.

Category: Condition / Infectious

See also: Staph aureus; Strep; Topical antibiotics

Intertrigo – Inflammation in skin folds from friction/moisture; may be secondarily infected.

Category: Condition

See also: Candidiasis; Barrier creams

Intense pulsed light (IPL) – Broad‑spectrum light device for dyschromia, redness, and hair reduction.

Category: Procedure / Device

See also: Vascular lesions; Photofacial

Isotretinoin – Systemic retinoid for severe acne; teratogenic—requires monitoring.

Category: Medication / Oral

See also: iPLEDGE; Nodulocystic acne J —

J

JAK inhibitor – Medication targeting Janus kinase pathways for inflammatory skin diseases (e.g., vitiligo, atopic dermatitis).

Category: Medication / Targeted

See also: Vitiligo; Atopic dermatitis; Immunomodulator

Junctional nevus – Melanocytic nevus located at dermo‑epidermal junction; flat/brown macule.

Category: Lesion / Pigmented

See also: Compound nevus; Intradermal nevus K —

K

Keratin – Structural protein of hair, nails, outer skin.

Category: Concept / Structural protein

See also: Keratinocyte; Nail plate

Keratosis pilaris – Rough follicular papules on arms/thighs from keratin plugging.

Category: Condition

See also: AHA; Urea; Gentle exfoliation

Keloid – Raised scar extending beyond wound margins; may itch/hurt.

Category: Scar type

See also: Hypertrophic scar; Silicone; PDL

Keratoderma – Thickening of palms/soles; acquired or inherited.

Category: Condition / Keratinization

See also: Hyperkeratosis; Emollients

Koebner phenomenon – Lesions appear at sites of trauma in conditions like psoriasis or lichen planus.

Category: Sign

See also: Psoriasis; Lichen planus L —

L

Lactic acid – Gentle AHA that exfoliates and hydrates; often better tolerated than glycolic.

Category: Ingredient / AHA

See also: AHA; Exfoliation

Lentigo – Flat brown macule from increased pigment; solar lentigines are ‘sun spots’.

Category: Lesion / Pigmented

See also: Freckle; Melasma

Lichen planus – Pruritic, violaceous, flat‑topped papules; may affect mucosa, hair, nails.

Category: Condition / Inflammatory

See also: Wickham striae; Nail dystrophy

Lichen simplex chronicus – Lichenified plaque from chronic scratching/rubbing.

Category: Condition / Neurodermatitis

See also: Pruritus; Break itch‑scratch cycle

Livedo reticularis – Net‑like violaceous discoloration from vascular changes.

Category: Finding / Vascular

See also: Vasculitis; Cold exposure

Lipoma – Soft, mobile benign fatty tumor under the skin; excisable if symptomatic.

Category: Lesion / Benign

See also: Excision; Ultrasound M —

M

Melanoma – Malignant tumor of melanocytes; early detection via ABCDE saves lives.

Category: Condition / Cancer

See also: ABCDE; Dermoscopy; Sentinel node

Melasma – Hormone/UV‑triggered hyperpigmentation; treated with sun protection and depigmenting agents.

Category: Condition / Pigment

See also: Hydroquinone; Tranexamic acid; Sunscreen

Microneedling – Collagen‑induction via controlled micro‑injury; improves scars, texture, tone.

Category: Procedure

See also: PRP; RF microneedling; Collagen

Microdermabrasion – Mechanical exfoliation using crystals/diamond tips for surface smoothing.

Category: Procedure / Device

See also: Exfoliation; Glow

Milia – Tiny white keratin cysts near surface, often periocular; may be extracted.

Category: Lesion

See also: Cyst; Keratin

Molluscum contagiosum – Benign viral bumps with central dell; common in children.

Category: Condition / Infectious

See also: Curettage; Cryotherapy

Morphea (localized scleroderma) – Localized sclerotic plaques due to excess collagen deposition.

Category: Condition / Autoimmune

See also: Scleroderma; Induration N —

N

Nail matrix – Germinal part producing nail plate; injury causes dystrophy.

Category: Anatomy / Nails

See also: Proximal nail fold; Lunula

Nail pitting – Small depressions in nail surface; common in psoriasis.

Category: Finding / Nails

See also: Psoriasis; Onycholysis

Neoplasm – Abnormal tissue growth—benign or malignant.

Category: Term / Oncology

See also: Tumor; Cancer

Nevus (mole) – Benign melanocytic proliferation (junctional, compound, intradermal).

Category: Lesion / Pigmented

See also: Atypical mole; Melanoma

Nodulocystic acne – Severe acne with nodules/cysts and scarring risk; often needs isotretinoin.

Category: Condition / Acne

See also: Isotretinoin; Scars

Nummular dermatitis – Coin‑shaped eczematous plaques; intensely pruritic.

Category: Condition / Inflammatory

See also: Emollients; Topical steroids O —

O

Occlusive – Ingredient forming protective film to reduce water loss (e.g., petrolatum).

Category: Ingredient / Hydration

See also: Emollient; Humectant; Barrier

Onycholysis – Separation of nail plate from bed; causes include trauma, psoriasis, infection.

Category: Nails / Finding

See also: Onychomycosis; Psoriasis

Onychomycosis – Fungal nail infection causing thickening/discoloration/debris.

Category: Condition / Infectious

See also: Tinea; Dermatophyte

Onychoschizia – Nail splitting/fragility; related to dehydration/trauma.

Category: Nails / Finding

See also: Biotin; Nail oils

Ocular rosacea – Eye involvement in rosacea—dryness, irritation, blepharitis.

Category: Condition / Inflammatory

See also: Rosacea; Demodex; Ophthalmology P —

P

Papule – Small, solid, raised lesion <1 cm.

Category: Morphology

See also: Pustule; Plaque; Nodule

Paronychia – Inflammation/infection around nail fold (acute or chronic).

Category: Condition / Nails

See also: Onycholysis; Candida

Patch – Flat, non‑palpable lesion ≥1 cm (smaller is macule).

Category: Morphology

See also: Macule; Plaque

Photodamage (photoaging) – UV‑induced changes—fine lines, dyspigmentation, texture loss.

Category: Concept / UV

See also: Sunscreen; Retinoid; Antioxidant

Phototherapy (NB‑UVB) – Medical UV treatment for psoriasis, vitiligo, and other dermatoses.

Category: Procedure / Light

See also: Psoriasis; Vitiligo

PIH (post‑inflammatory hyperpigmentation) – Darkening after inflammation/injury; more prominent in deeper tones.

Category: Finding / Pigment

See also: Sunscreen; Retinoid

Pityriasis rosea – Self‑limited rash with ‘herald patch’ followed by Christmas‑tree distribution.

Category: Condition / Inflammatory

See also: Viral exanthem; Itch relief

Pityriasis versicolor (tinea versicolor) – Yeast overgrowth causing hypo/hyperpigmented macules with fine scale.

Category: Condition / Infectious

See also: Malassezia; Antifungal shampoos

Plaque – Raised, flat‑topped lesion ≥1 cm; classic in psoriasis.

Category: Morphology

See also: Papule; Scale; Psoriasis

Porphyria cutanea tarda – Blistering photosensitivity on hands/forearms; related to porphyrin metabolism.

Category: Condition / Metabolic

See also: Hepatitis C; Iron overload

Port‑wine stain – Congenital capillary malformation (red‑purple patch); treatable with vascular lasers.

Category: Condition / Vascular

See also: Pulsed‑dye laser

PRP (platelet‑rich plasma) – Autologous platelets to stimulate healing/collagen in skin/scalp procedures.

Category: Procedure / Regenerative

See also: PRF; Microneedling; Hair restoration

PRF (platelet‑rich fibrin) – Autologous fibrin matrix for slow release of growth factors.

Category: Procedure / Regenerative

See also: PRP; Microneedling

Psoriasis – Chronic immune‑mediated disease with erythematous plaques and silvery scale.

Category: Condition / Inflammatory

See also: Plaque; Biologics; Nail pitting

Purpura – Non‑blanching red‑purple lesions from extravasated blood; various causes.

Category: Finding / Vascular

See also: Petechiae; Vasculitis

Pyogenic granuloma – Rapidly growing friable red papule that bleeds easily; benign vascular lesion.

Category: Lesion / Vascular

See also: Trauma; Shave/cautery Q —

Q

Q‑switched laser – Laser technology delivering high‑energy pulses for pigment/tattoo removal.

Category: Procedure / Laser

See also: Nd:YAG; Picosecond laser R —

R

Retinoid – Vitamin‑A derivatives (topical/oral) for acne and photoaging; collagen support.

Category: Ingredient / Rx & OTC

See also: Tretinoin; Adapalene; Isotretinoin

Retinaldehyde – Vitamin A precursor; potent yet often better tolerated than tretinoin.

Category: Ingredient / OTC

See also: Retinoid; Tretinoin

Rhinophyma – Phymatous subtype of rosacea with thickened nasal skin.

Category: Condition / Rosacea

See also: Rosacea; Laser; Debulking

Ringworm (tinea corporis) – Dermatophyte infection of body skin causing annular plaques with scale.

Category: Condition / Infectious

See also: Tinea; Onychomycosis

Rosacea – Chronic facial redness/flushing +/- papules/pustules and ocular symptoms.

Category: Condition / Inflammatory

See also: Erythema; Telangiectasia; Demodex

RF microneedling – Microneedling enhanced with radiofrequency for tightening/texture.

Category: Procedure / Device

See also: Microneedling; Collagen S —

S

Scabies – Infestation by Sarcoptes scabiei causing intense nocturnal itch; burrows/web spaces.

Category: Condition / Infectious

See also: Permethrin; Household treatment

Scleroderma (systemic sclerosis) – Autoimmune fibrosis/vasculopathy causing skin thickening and organ involvement.

Category: Condition / Autoimmune

See also: Morphea; Raynaud

Sebaceous gland – Oil‑producing gland attached to follicles; overactivity contributes to acne.

Category: Anatomy / Appendage

See also: Sebum; Pilosebaceous unit

Seborrheic dermatitis – Redness and greasy scale on scalp/face due to inflammation and yeast overgrowth.

Category: Condition / Inflammatory

See also: Dandruff; Antifungal; Anti‑inflammatory

Seborrheic keratosis – Benign, stuck‑on appearing brown growths; removable for symptoms/cosmetics.

Category: Lesion / Benign

See also: Cryotherapy; Curettage

SPF (sun protection factor) – Measure of UVB protection; SPF 30 blocks ~97% with correct application.

Category: Measurement / Sunscreen

See also: Broad‑spectrum; UVA; UVB

SCC (squamous cell carcinoma) – Common skin cancer from keratinocytes; potential to metastasize if neglected.

Category: Condition / Cancer

See also: Actinic keratosis; Mohs

Solar lentigo – Sun‑induced pigmented macule (‘sun spot’).

Category: Lesion / Pigmented

See also: Lentigo; Sunscreen

Syringoma – Benign sweat duct tumors—small, firm papules, often periorbital.

Category: Lesion / Benign

See also: Electrodesiccation; Laser T —

T

TEWL (transepidermal water loss) – Water loss through epidermis; increased when barrier impaired.

Category: Measurement / Barrier

See also: Barrier; Humectant; Occlusive

Telangiectasia – Visible dilated capillaries, common in rosacea and sun damage.

Category: Finding / Vascular

See also: Rosacea; Vascular laser

Telogen effluvium – Diffuse hair shedding after stress/illness/hormonal change.

Category: Condition / Hair

See also: Alopecia; Androgenetic alopecia

Tinea – Dermatophyte infections of skin/hair/nails named by site (capitis, pedis).

Category: Condition / Infectious

See also: Onychomycosis; Tinea versicolor

Tinea capitis – Scalp dermatophyte infection in children; may cause hair loss.

Category: Condition / Infectious

See also: Kerion; Antifungals

Tinea pedis – Athlete’s foot—itchy, scaly interdigital or moccasin distribution.

Category: Condition / Infectious

See also: Onychomycosis; Antifungals

Tranexamic acid – Topical/oral agent reducing melasma/dyspigmentation via plasmin pathway.

Category: Medication / Pigment

See also: Melasma; Hydroquinone; Sunscreen

Tretinoin – Gold‑standard topical retinoid for acne/photoaging.

Category: Medication / Topical

See also: Retinoid; Adapalene

Trichotillomania – Hair‑pulling disorder causing patchy alopecia and broken hairs.

Category: Condition / Behavioral

See also: Alopecia; CBT U —

U

Ulcer – Full‑thickness skin loss; causes include pressure, vascular disease, neuropathy.

Category: Lesion / Wound

See also: Wound care; Debridement

Urea – Humectant/keratolytic used to hydrate and soften thick scale.

Category: Ingredient / Hydration

See also: Emollient; Keratosis pilaris

Urticaria (hives) – Transient itchy wheals from histamine release; multiple triggers.

Category: Condition / Allergic

See also: Angioedema; Antihistamines

UVA / UVB – Ultraviolet A (aging) and B (burning) rays; both contribute to photoaging/skin cancer.

Category: Concept / Photobiology

See also: Broad‑spectrum sunscreen; UPF clothing V —

V

Varicella (chickenpox) – Primary VZV infection with pruritic vesicles in crops.

Category: Condition / Infectious

See also: Zoster; Antivirals

Vascular laser (PDL) – Laser targeting hemoglobin to treat redness/telangiectasia/angiomas.

Category: Procedure / Laser

See also: Pulsed‑dye laser; IPL

Vellus hair – Fine, light, soft hair covering much of body.

Category: Anatomy / Hair

See also: Terminal hair; Androgens

Vesicle – Small fluid‑filled blister <5 mm; larger is bulla.

Category: Morphology

See also: Bulla; Erosion

Vitiligo – Autoimmune loss of melanocytes causing depigmented patches.

Category: Condition / Pigment

See also: Phototherapy; JAK inhibitor W —

W

Wart (verruca) – HPV‑induced benign growths on skin; common on hands/feet.

Category: Condition / Infectious

See also: Cryotherapy; Salicylic acid

Wheal – Transient, raised, itchy lesion of urticaria.

Category: Morphology

See also: Urticaria; Histamine

Wood’s lamp – UV light exam aiding pigment disorder and infection evaluation.

Category: Tool / Diagnostic

See also: Vitiligo; Tinea; Erythrasma

Wound healing – Phases: hemostasis, inflammation, proliferation, remodeling.

Category: Concept / Wound

See also: Granulation tissue; Scar X —

X

Xanthelasma – Yellowish cholesterol‑rich plaques on eyelids.

Category: Lesion / Metabolic

See also: Xanthoma; Lipids

Xanthoma – Yellow papules/plaques from lipid deposition; associated with dyslipidemia.

Category: Lesion / Metabolic

See also: Hyperlipidemia; Xanthelasma

Xerosis – Abnormally dry skin from reduced moisture/lipids; worsens in low humidity.

Category: Condition / Dryness

See also: Emollient; Humectant; Barrier repair Y —

Y

Yellow nail syndrome – Triad: yellow thick nails, lymphedema, respiratory disease.

Category: Condition / Nails

See also: Lymphedema; Bronchiectasis Z —

Z

Zinc oxide – Mineral UV filter providing broad‑spectrum protection; reef‑safe.

Category: Ingredient / Sunscreen

See also: Titanium dioxide; Mineral sunscreen

Zoster (herpes zoster) – See Herpes zoster (shingles).

Category: Condition / Infectious

See also: Varicella; Antivirals

Disclaimer

This glossary is educational and does not replace a consultation with a board‑certified dermatologist. Treatment decisions should be personalized by a qualified clinician.