pathology of the skin

8/10/2019 Pathology of the Skin

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into a crust

BULLOUS AND

VESICULAR

DERMATITIS

$esicles are fluid filled

ca&ities less than *mm indiameter !ull are greater than

*mm !oth structures are short

li&ed and turn into crust

Spongiosus +dema !etween keratinocytes(intercellular)

Intrace!ar edema $esicles form when edema is

se&ere enough thatkeratinocytes are lost or

displaced

ydropic degeneration +dema within the !asal

epiderdmal cells causes

depigmentation of the skin

utoimmune d, lupus

erythematosis and

dermatomyositis, drugreactions

Ballooning degeneration "ntracellular edema within

superficial keratinocytes

$iral skin diseases (po- &irus,

foot and mouth, &esicularstomatitis, &esicular

e-anthema, swine &esicular

disease)

Pemphigus &ulgaris Supra!asilar &esicle

containing acantholytic cellsskin and oral ca&ity

! directed against

keratinocyte

Bullous pemphigoid Su!epidermal &esicle skin

and oral ca&ity

! against the !asement

mem!raneNECROTI"IN#

DERMATITIS

Necrosis of epidermal cellsleads to ulceration of the skin

macule is a flat discolored

area of the skin, papule isslightly raised area !oth are

usually red (erythema)


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e&entually progress to a crust

phase

+rythema multiforme Necrosis of singlekeratinocytes throughout

epidermis

d&erse drug reaction inassociation with systemic

infection or neoplasia

(immune mediated)

Small animals

o-ic epidermal necrolysis More se&ere form, fullthickness epidermal necrosis

d&erse drug reaction inassociation with systemicinfection or neoplasia

(immune mediated)

Small animals

Burns +pidermis and dermis are

necrotic

Photosensitiation Non pigmented areas of skin

necrotie

"ngestion of photodynamic

agent in the feed or secondary

to chronic li&er disease

/arge animals

E$UDATIVE ANDULCERATIVE

DERMATITIS

Produce crusts or secondaryulcers on the skin, may !e

se&ere spongiosus of theepidermis, due to edema

Aer%ies "ntensely pruritic, may !e

seasonal

ypersensiti&ity reaction to

antigen that is inhaled oringested. Most common cause

of e-udati&e dermatitis.

+osinophils in cats and horses

!ut not dogs.

atopy Name gi&en to inhalant allergy Most common

'ood allergy Not as common

+osinophilic granulomacomple-

Nodules or papules in the skinalong with ulcers

0 histologically differentdiseases

%at and horse, sometimes dog

llergic contact dermatitis /esions &ary from papules to

crusts and are commonlyfound on sparsely haired

regions (feet, &entral !elly)similar to poison i&y

%ontact of skin with an

allergic su!stance (chemicals,plastics)


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"rritant contact dermatitis /esions in sparsely haired

regions, erythematous papulesor ulcers and crusts of

e-udati&e dermatitis

1irect contact of the skin with

irritating o!2ect3 soap, drug,acid, detergent

Pyotraumatic dermatitis

4hot spots5

Se&ere e-udati&e dermatitis Self inflicted trauma of !iting

and scratching due to pain and

pruritis of allergic skin disease

1og

&'PER(ERATOTIC

DISEASES

yperkeratosis +-cess keratin, flakes orscales (se!orrhea)

# orthokeratotic hyperkeratosis(keratinied cells lack a

nucleus)

Parakeratosis +-cess keratin#parakeratotic hyperkeratosis

(nucleus of the cell is retained)

6inc or $itamin deficiency

Se!orrhea 1ry or oily # rare primary disease#inherited defect of keratin

cells

# secondary disease iscommon# after allergy,

parasites, infection, endocrinedisease

# %ocker spaniel

# ll dogs

&'PERPLASTIC

DERMATITIS

%haracteried !y histologic

appearance two lesions ofchronic skin disease

canthosis yperplasia of the epidermis,

skin thickened grossly withleathery te-ture

(ichenification), there is also

increased melanin pigmentmaking the skin appear darker


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(h)perpi%mentation)

1iseases of the 1ermis

PERIVASCULAR

DERMATITIS

Most skin diseases ha&e this,

peri&ascular inflammation

may lead to diffuse or nodular

"nterface dermatitis "nflammation of the

superficial dermis at the

epidermal7dermal 2unction(o!scuring the distinction

!etween these two layers)

utoimmune skin diseases

/ichenoid dermatitis 1ense !and of inflammation

in the superficial dermis,

distinct and sharplydemarcated from the ad2acent

tissue

utoimmune skin disease

NODULAR DERMATITIS 'irm swellings in the dermisor su!cutis, palpate as a mass,

secondary ulceration of the

o&erlying skin

"nfections %hronic inflammation Bacterial, fungal, parasitic

Sterile

8ranulomatous7pyogranulomatous

nodular dermatitis

"nflammation of the dermis

centered on adne-a

Not infectious, responds to

steroid therapy

1og

'urunculosis Secondary to folliculitis3 whenhair follicles rupture hair andkeratin are released into the

dermis causing se&ere

inflammation.9: when follicles are

traumatied (scratching,


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!iting, licking)

Panniculitis (superficial muscle) "nflammation of the su!cutis

without in&ol&ement of thedermis or epidermis

Physical in2ury, infection,

nutritional ($it + deficiency),idiopathic

%ats and dogs

Neoplasia

ALOPECIA /oss of hair Primary or secondary, occurs

in any of the skin diseasesalready discussed

+ndocrine Skin 1isease Bilaterally symmetrical

(perineum, !ack, flanks),histologically there is no

dermatitis, atrophy of the hairfollicles and se!aceous glands

Most important cause of

primary alopecia,hypothyroidism,

hyperestrogenism,hyperadrenocorticism,

hyposomatostatin

/ess common causes of primary

alopecia

'eline psychogenic, e-cessi&e

licking, post clipping, telogenefflu&ium due to stress or

systemic disease, folliculardysplasia

%utaneous Neoplasia3 the skin has more neoplasms than any other organ system, many of these neoplasms are uni;ue to the dog

Name %haracteristics


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stomach

%ow3 eye%at3 nose, pinna

Melanoma Melanocytes of epidermis

in&ol&ed, !enign or

malignant, pigmented or

non

1og3 skin (!enign),

mouth (malignant)

orse3 perineum of

grays (!enign !ut large,multiple masses)

Papilloma Se!aceous glandtumors

:are, adenoma or#carcinoma (more

common)

1og

Sweat gland tumors :are, adenoma or

#carcinoma (notaggressi&e)

1og


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> Perianal 8land tumors $ery common, !enign

may ulcerate, the tumorrecurs

Male 1ogs

nal Sac umors Malignant and aggressi&e 'emale 1ogs

DERMAL

NEOPLASMS

> istiocytoma Benign, &ery common,grow ;uickly, red, will

regress

'rom langerhan cells ofthe epidermis

=9UN8 dogs

> Mast cell tumors $ery common, !enign ormalignant, need to resect a

wide area for remo&al

1ogs, also cats andhorses

'i!roma :are, !enign 'rom fi!ro!lasts 1og and cat

'i!rosarcoma %ommon, malignanttumor, locally in&asi&e,

recurs fre;uently

Spontaeneously, orsecondary to

&accination or sarcoma&irus

%ats and dogs

Sarcoid 'i!ro!last tumor, &ery

common, !enign, high rate

of local recurrence

Bo&ine papilloma &irus orse

/ipoma $ery common, !enign 'at cells or adipocytes 1og

Plasma %ell umor Uncommon, !enign Skin and oral ca&ity

emangioma %ommon, !enign $ascular endothelium 1og

emangiosarcoma Uncommon, malignant

recurs locally, maymetastasie

> ccount for ?*@ of the tumors in dogs >

pathology of the skin

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