Rash

A rash (French rache = a sore) is any abnormal change in the skin color, or texture (1).

By another definition, a rash is breaking out of the skin (eruption, Greek exanthema) (2).

Rashes According To Size, Shape, and Consistency

(Click links for pictures)

Macule

A macule (Latin macula = spot) is a small (< 1cm) skin discoloration in the level of the skin, neither raised, nor depressed, and therefore non-palpable (3).

Patch

A patch is a macule that exceeds 1cm in size (3).

Papule

A papule (Latin papula = pimple) is a small (<1cm) palpable, raised, solid, flat skin spot (3).

Plaque

A plaque is a broad (> 1cm) papule (4).

Vesicle (Blister)

A vesicle (Latin vesicula = small bladder) is a small (< 1cm) circumscribed, fluid-filled elevation within upper skin layer (epidermis). It has a thin wall, and is often translucent (4).

Bulla

A bulla (Latin bulla = bubble) is a vesicle that exceeds 1cm in size.

Pustule

A pustule (Latin pustula = inflamed sore) is a pus-filled vesicle.

Crust

A crust is rough, flat or bumpy, fragile, dried secretion of oil glands, ruptured fluid-filled skin lesions, or dried blood. It is usually red, brown or yellowish, and falls off the skin in few days or weeks, in one or several pieces.

Wart (Verruca)

A wart (Latin verruca) is a cauliflower-like or solid growth from the outer layer of the skin (epidermis). It is caused by virus, and they typically disappear after few months (or sometimes years) without consequences.

Nodule

A nodule (from node = knob) is a palpable collection of solid tissue in the skin, less than 1 cm in size. Nodules may arise from the skin or tissues under the skin, and may be above, level with, or below the skin surface.

Induration

Induration is localized hardening of a skin.

Lichenification

Lichenification (lichen = a flat plant that grows on rocks and trees) is visible and palpable localized hardening of the skin and represents a chronic eczema. 

Maceration

Maceration (Latin macerare = make wet) is a raw wet tissue.

Red Rashes

Erythema

Erythema (Greek euruthema = red) refers to skin redness that affect localized patch (> 1cm) of the skin, and is due to inflammation of the skin, like in sunburn, systemic lupus erythematosus, erythema nodosum, etc. Erythema results from dilation and congestion of skin capilaries.

Eczema

An eczema (Greek ekzein = to erupt) refers to localized area of inflamed skin that is red, scaly, and covered with vesicles or crusts. It is a result of allergic or non-allergic response to skin irritation.

Hives (Urticaria)

Hives or urticaria (Latin urtica = nettle) is slightly raised, pink or red, bumpy or patchy rash that usually itches. It is a symptom of allergic reaction, mediated by histamine, and represents accumulation of fluid and inflamatory cells that came out from skin blood vessels. It may be a result of skin irritation, or allergy to foods, medicines, hair dyes, etc.

A weal is a raised bump on the skin that indicates an allergy in a skin prick test.

Angioedema

Angioedema (Greek angio- = vessel related; oidema = swelling) is hives with swelling that occupies deep layers of the skin.

Interruption of Skin Integrity

Scratch (Excoriation)

A scratch is punctual or linear abrasion of the upper layer (epidermis) of the skin.

Wound

A wound is a type of injury in which the skin is cut, torn, or punctured.

Erosion

An erosion (Latin erodere = gnaw, eat away) is a superficial open wound, with loss of only superficial layers of the skin.

Fissure

A fissure (Latin fissura = cleft) is a linear crack in the skin, usually on the site when skin and mucosa meet (lips, anus).

Ulcer

An ulcer (Latin ulcus) is discontinuing of the skin with a localized loss of upper skin layers (epidermis and parts of dermis).

Thick or Scald Skin

Keratosis

A keratosis (Greek keras = horn) is thickening of uppermost layer of skin, consisting from dead skin cells.

Scar (Cicatrix)

A scar (Latin cicatrix) is a band or a patch of connective fibrous tissue that replaces normal skin after wound healing. It appears after an injury, surgical cut of the skin, burns, ulcers, acne, or other lesion where skin integrity was interrupted. Scar may get discoloured, and may itch. There’s no hair, oil or sweat glands in the scar. Scars are permanent changes.

Keloid

A keloid (Greek chele = claw) is a hardened area of fibrous skin that may develop from a scar, or inflammation of skin glands.

Scaling (Exfoliation)

Scaling is shedding of small flakes or large patches of upper layer (epidermis) of the skin (like in dandruff, sunburn or fungal infection of the foot).

Thin Skin

Skin Atrophy

Skin atrophy (Latin atrophia = wasting consumption) is wasting of skin due to local irritation, lack of nutrients, impaired blood supply, long term use of topical etc. It may be localized or general. Hair, oil and sweat glands may be lost on affected area. Skin

Blood and Vessels Related Changes

Temporary Red Skin – Hyperemia

Hyperemia (Latin hyper- = over; -emia = related to blood) is temporary skin redness due to increased blood flow in particular skin, or mucosal area.

Pale Skin – Pallor

Pallor (Latin pallere = to be pale) is skin paleness due to decreased blood flow in skin vessels due to their narrowing. Possible causes are anemia, low body or external temperature, dehydration, low blood pressure, stress, tumors secreting excessive amounts of cortisol or adrenalin, or medications.

Blanching Rash

Blanching rash is a temporary white discoloration of localized skin area after pressing on it. It is due to blood, squeezed away from the blood vessels in the pressed area.

Blue Skin (Cyanosis)

Skin becomes blue or cyanotic (Greek cyanos = dark blue) due to poorly oxygenated venous blood.

Bleeding (Hemorrhage)

Bleeding is flowing of blood out from injured vessels onto surface of the skin or mucosa (or into internal organs).

Bruise (Contusion, Hematoma)

A bruise or contusion (Latin contusio = crushing, bruising) is accumulation of blood under the skin, when vessels in the skin or under-skin tissues are broken, but skin remained intact. Bruise is first red, then blue, and finally greenish/yellow.

Ecchimosis

Ecchimosis (Greek ekchymosis = a pouring out) is a small (but > 1 cm) flat purplish bruise beneath the skin (or mucosa).

Purpura

Purpura (Latin purpura = purple) is small (3mm – 1 cm) purplish bruise. It does not blanch on applying the pressure.

Petechia

A Petechia (Lat petecchia (pl. = petechiae) = spot on skin) is a small (< 3 mm) red or purple bruise. It does not blanch on applying the pressure.

Ecchimoses, purpurae, and petechiae are caused by trauma, blood or vascular disorders.

Spider Nevus (Telangiectasia)

Spider nevus or telangiectasia (Latin tel- = transmission over a distance; angi- = vessel related; ectasia = widening, dilation). It is a small (few mm to few cm) spider like net of tinny blood vessels, appearing under the skin anywhere on the body, but mostly on the face and upper chest. It may be due to sun exposure, alcohol abuse, liver disease, hormonal imbalance, hemangioma, etc.

Masses

Tumor

A tumor ( Latin tumor= swelling) refers to any swelling or overgrowth of the tissue that exceeds 1 cm in size. Tumor is NOT a synonym for cancer.

Swelling (Edema)

Swelling or edema (Greek oidema= swelling) is enlargement of an organ due to collection of the fluid in the tissues.

Bump

A bump is any small (few mm) elevation from the skin surface.

Lump

A lump is bulging of the skin, few to several centimeters in size, caused by a mass of tissue or enclosed fluid collection within or under the skin.

Cyst

A cyst (Latin cyst = bladder, pouch) is enclosed sac, having a distinct membrane, and it is clearly divided from the nearby tissue. It may contain air, fluid, or semi-solid material. A cyst usually develops from clogged sweat or oil glands or hair follicles.

Boil (Abscess)

A boil or abscess (Latin abscedere = withdraw, depart) is a collection of pus within a tissue or skin, usually due to bacterial infection. It may appear as a bulge that eventually drains to the surface.

Furuncle

A furuncle (Latin furunculus = sneak thief, boil) is a small boil due to bacterial infection of a hair follicle.

Carbuncle

A carbuncle (Latin carbunculus = live coal, red tophus) is a group of furuncles that have merged together.

Hyper-Pigmentations

Nevus

Nevus (pl. nevi) is any chronic, benign, circumscribed hyper-pigmented lesion.

Birthmark is a blemish on the skin formed before birth, and visible at birth or few days/weeks after birth. Examples are Port-wine stain or Nevus flameus, strawbery mark, and Mongolian blue spot.

A mole is melanocytic nevus ((formed by pigment producing cells – melanocytes). It appears as dark spot or small growth on the skin. Moles may be acquired or congenital. A beauty mark or beauty spot is a mole appaearing on the face. Mongolian spot is a large, congenital, bluish discoloration on the back of Asian babies.

Lentigo (Latin lentigo (pl. lentigines) = lentile shaped) is brown discoloration on the skin (brown nevus).

Hypo-Pigmentations

Albinism

Albinism (Latin albus = white) is genetic disorder with total lack of pigment melanin in the skin (white skin), eyes (red eyes) and hair (white hair).

Vitiligo – Leukoderma

Vitiligo or leukoderma (Greek leukos = white; dermis = skin) is chronic disorder of melanocytes that appear as multiple pale patches (depigmentation) on various parts of the body.

Related Articles:

References:

  1. Rash definition (nlm.nih.gov/medlineplus)
  2. Rash definition (medterms.com)
  3. James, William; Berger, Timothy; Elston, Dirk (2005) Andrews’ Diseases of the Skin: Clinical Dermatology (10th ed.). Saunders. Page 15. ISBN 0721629210.
  4. James, William; Berger, Timothy; Elston, Dirk (2005) Andrews’ Diseases of the Skin: Clinical Dermatology (10th ed.). Saunders. Page 16. ISBN 0721629210.

  • Share/Save/Bookmark

Further Reading :
  • Itchy Rash
  • Causes of Non-Itchy Rash
  • Itchy Skin Rashes