Infectious disorders Skin Inflammatory disorders6 Scabies Burrow •31 Skin Pathology Outline • Introduction • Infectious disorders • Inflammatory disorders •32 • Common,

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Kristine Krafts, M.D.

SkinPathology

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Skin Pathology Outline

• Introduction

• Infectious disorders• Inflammatory disorders

• Bullous disorders

• Benign neoplasms

• Malignant neoplasms

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• Introduction

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corneum

lucidum

granulosum

spinosum

basale

Thick skin

Thin skin

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Erythema: redness

Macule: flat lesion

Patch: a large macule (<1cm)Papule: a raised lesion

Plaque: a large papule (>1cm)Vesicle: a blister

Bulla: a big blisterPustule: a blister that contains pus

Clinical Terms You Should Know

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• Introduction

• Infectious disorders

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Impetigo

• Staph aureus or Strep pyogenes

• Children

• Face

• “Honey-crusted” pustules

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Impetigo

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• Staph aureus or Strep pyogenes

• Adults

• Face/scalp

• Sharply-circumscribed, erythematous plaques

Erysipelas

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Erysipelas

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• Many potential organisms

• Excessive pain following small injury

• Rapidly progressive tissue necrosis and gangrene

• Need early, aggressive treatment (surgery and IV antibiotics)

Necrotizing Fasciitis

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Necrotizing fasciitis

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• Proprionibacterium acnes

• Sebaceous glands get plugged, then bacteria cause inflammation of the hair follicle/sebaceous gland

• Comedones and/or pustules

Acne vulgaris

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Types of Acne Lesions

Sebaceous gland

Bacteria

Not covered by skin

Covered by skin Neutrophils

Dead cells and debris

Open comedone

(whitehead)

Closed comedone (blackhead)

Pustules

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Acne vulgaris

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Acne vulgaris

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• Immune-mediated disease (no known microbial trigger)

• Follicles are inflamed and plugged

• Four stages: 1. Flushing episodes2. Persistent redness and telangiectasias3. Pustules4. Rhinophyma

Acne rosacea

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Rosacea

Redness and telangiectasia Rhinophyma

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• Caused by dermatophytic (skin-loving) fungi likemicrosporum and trichophyton

• Red, scaly, “ring-shaped” lesions

• Named by anatomic site • tinea corporis = ringworm on body in general• tinea pedis = ringworm of foot (athlete’s foot)• tinea cruris = ringworm in groin (jock itch)

Ringworm (tinea)

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Tinea corporis

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• Fungus: Sporotrichum schenkii

• “Rose gardener’s disease”

• Painless papule, then open sore

Sporotrichosis

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Sporotrichosis

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• HPV (usually serotypes 2 and 4)

• Common wart

• Most common on extremities

• Most regress spontaneously

Verruca vulgaris

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Verruca vulgaris

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• Pox virus

• Centrally-umbilicated red papules

• Very contagious

Molluscum contagiosum

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Molluscum contagiosum

Umbilication

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• Usually HSV; sometimes drug-related

• “Target” lesions and/or vesicles on skin, mucous membranes

• Stevens-Johnson syndrome is a related disease characterized by skin necrosis.

Erythema multiforme

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Erythema multiforme

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• Parasite: Sarcoptes scabei

• Hands/wrists, abdomen/groin

• Itchy rash, may see “burrows”

• Highly contagious

Scabies

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Scabies

Burrow

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• Introduction


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• Common, inherited, autoimmune disease

• Itchy red lesions with silvery scales

• Most common on elbows, knees, scalp

• Patients may also have arthritis

Psoriasis

•33Psoriasis

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• Common, chronic, immune-mediated disease

• Skin: purple polygonal papules

• Mucous membranes: lacy-appearing lesions (Wickham’s striae), erosions, or white patches

Lichen planus

•35Lichen planus

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Wickham’s striae

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• Introduction



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• Antibodies against spot desmosomes

• Superficial bullae

• Mouth first, then skin

Pemphigus vulgaris Bullous pemphigoid

• Antibodies against hemidesmosomes

• Subepidermal bullae

• Groin, axillae, arms

Two bullous diseases

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Antibodies against spot desmosomes

(between epidermal cells)

Antibodies against hemidesmosomes

(beneath epidermal cells)

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Separation between epidermal cells

Separation between epidermis and dermis

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Ruptured bullae Intact bullae

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• Introduction




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Nevus (mole)

• Benign neoplasm of melanocytes

• Round, evenly-pigmented

• Progresses from junctional to compound to intradermal over time

• Melanoma occasionally develops in nevi –so watch for changes (size, shape, color)

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Junctional nevus Compound nevus Intradermal nevus

Melanocytes at dermal-epidermal junction

Melanocytes at junction AND in dermis

Melanocytes in dermis

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• Common benign tumor of blood vessels

• “Strawberry hemangioma” occurs at birth, usually regresses within a year

Hemangioma

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Hemangiomas Strawberry hemangiomas

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Keratoacanthoma

• Rapidly-growing, crater-like nodule

• May evolve into squamous cellcarcinoma (must be removed)

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Keratoacanthoma

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Seborrheic keratosis

• Common benign epidermal tumor

• Increasing incidence with age

• Brown-grey, velvety-waxy plaque

• “Stuck-on” appearance

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Seborrheic keratoses

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Actinic keratosis

• Dysplastic epidermal cells

• Ill-defined, rough patches

• Related to sun exposure (“actinic”)

• Considered pre-malignant

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Actinic keratosis

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• Introduction




• Malignant neoplasms

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Basal cell carcinoma

• Malignant tumor of cells in basal layer of epidermis

• Raised, “pearly” nodule

• Older patients, sun-exposed skin

• Locally aggressive, but almost never metastasizes!

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Basal cell carcinoma “rodent ulcer”

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Squamous cell carcinoma

• Malignant tumor of squamous cells

• Reddish nodule or plaque

• Older patients, sun-exposed skin

• Can metastasize

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Melanoma

• Malignant tumor of melanocytes

• All ages, sun-exposed skin

• Worst prognosis of all skin cancers

• Prognosis directly related to depth of invasion

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Asymmetry (in shape or color)Border (irregular)Color (variegated) Diameter (usually >6mm)Elevation (or textural change within lesion)

Is it melanoma, or just a mole?

Look for:

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More examples of melanoma

Amelanotic melanoma

•65Oral melanoma

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Acral melanoma

•67Melanoma

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Melanoma prognosis

• Depth of invasion = most important factor

• Measure depth by Clark levels or Breslow thickness

• Presence of metastases = worse prognosis

• Ulcerated surface = worse prognosis

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Clark levels and 10-year survival

90%

70% 60% 30%

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Breslow thickness and 10-year survival

90% 1 mm2 mm3 mm4 mm5 mm

80%60%50%40%

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Documents

Infectious disorders Skin Inflammatory disorders6 Scabies Burrow •31 Skin Pathology Outline • Introduction • Infectious disorders • Inflammatory disorders •32 • Common,