L7: Path of the Integumentary System (Ginn)

Question 1

fxs of skin

Answer 1

• temp/BP regulation
• fluid regulation
• protection
• sensation
• nutrient metabolism
• immune functions: SALT

Question 2

layers of skin

Answer 2

panniculus (deep fat layer)
adnexa (sebaceous, apocrine glands, hair follicles)
dermis (prod. by fibroblasts)
basement membranes
epidermis (surface of skin; composed of s. basal/s. spinosum/s.granulosum/s.corneum)

Question 3

stages of hair follicle

Answer 3

anagen (growth)
catagen (cessation)
telogen (resting)

Question 4

acanthosis***

Answer 4

hyperplasia of the epidermis

-can be regular (ie. drug rxn), irregular, paillated (ie. seborrhea, viral infection) or pseudocarcinomatosis

Question 5

hyperkeratosis

Answer 5

increased width of stratum corneum
-2 types: ORTHOKERATOTIC (cells of stratum corneum develop normally but lose nuclei too quickly; ie. chronic insult to skin) or PARAKERATOTIC (cells haven’t matured normally and haven’t lost nuclei normally; signals epi not returning normally, underlying dz such as chronic liver dz, diabetes, pancreatic tumor)

Question 6

ichthyosis

Answer 6

congenital hyperkeratosis

Question 7

seborrhea

Answer 7

condition in which flakes of dead skin are shed from the epidermis and hair follicles

Question 8

dyskeratosis

Answer 8

• premature keratinization of cells in the epidermis
• often seen in parakeratosis**
• often due to sun damage
• cells taking first steps to neoplasm

Question 9

apoptosis

Answer 9

individual cell necrosis

• programmed cell death
• most common cause = drug rxn
• causes erythema multiforme

Question 10

2 types of epidermal necrosis

Answer 10

• apoptosis

- full thickness epidermal necrosis (also usually drug rxn; ex- toxic epidermal necrolysis)

Question 11

cutaneous atrophy

Answer 11

• not getting enough blood, hormones (most common), etc.
• can affect epidermis, hair follicles, and dermis
• telogen hair follicles –> alopecia
• acantholysis: loss of intercellular connections, such as desmosomes, resulting in loss of cohesion b/w keratinocytes
• epidermis becomes very thin

Question 12

spongiosis

Answer 12

intercellular edema

-type I hypersensitivity rxns

Question 13

hydropic degeneration

Answer 13

fluid accum. in basal epidermis

• type of intracellular edema
• can form blisters

Question 14

ballooning degeneration

Answer 14

keratinocytes w/n epidermis balloon up and can burst

• type of intracellular edema
• often a viral cytopathic effect
• mech. of vesicle formation

Question 15

Acantholysis

Answer 15

loss of intercellular connections, such as desmosomes, resulting in loss of cohesion b/w keratinocytes

• enzymatic destruction (caused by neuts), type II hypersensitivity (ie. pemphigus foliaceus)
• main differentials: bacterial or fungal rxn, true cytotoxic rxn**

Question 16

most common autoimmune disease

Answer 16

pemphigus foliaceus

Question 17

3 locations of vesicles/bullae**

Answer 17

1) subepidermal (worst, ulcerative; bolus phemphigoid, burns, toxic epidermal necrosis, EB or lupus can cause)
2) subcorneal (pemphigus foliaceous)
3) suprabasal (pemphigus vulgaris can cause)

Question 18

path. of vesicles or pustules

Answer 18

• marked spongiosis, hydropic or ballooning degen.
• enzymatic/immune/mechanical or destruction
• genetic structural defects

Question 19

Pautrier’s microabscesses

Answer 19

• collection of lymphocytes in the epidermis –> pustule

- indicative of epitheliotrophic lymphoma aka mycosis fungoides (neoplastic dz. of lymphocytes)**

Question 20

3 possible fillings of pustules

Answer 20

neuts
eos
Pautrier’s microabscesses

Question 21

what causes hypopigmentation?

Answer 21

damage to melanocytes or BM, defects in form. of melanin or lack of melanocytes

Question 22

3 causes of folliculitis***

Answer 22

demodex
dermatophytes
bacteria (staph)

Question 23

urticaria

Answer 23

hives

-compressible, fluid-filled

Question 24

mucinosis

Answer 24

• excess mucin (mucin = glycosaminoglycan substance b/w collagen bundles)
• Sharpeis
• can be caused by hormonal imbalance like hypothyroid or feline eosinophilic plaques

Question 25

infiltrate of eos or mast cells --> collagen

Answer 25

degeneration/collagenolysis

Question 26

2 categories of collagen mineralization

Answer 26

1) dystrophic (hyper?adrenocorticism, chronic renal failure) | 2) metastatic

Question 27

elastosis

Answer 27

added compliance/elasticity of skin by inc. elastin

Question 28

calcinosis cutis

Answer 28

deposition of Ca salts - hyperadrenocorticism - eventually ulcerates

Question 29

things that cause vasculitis

Answer 29

``` thrombosis ischemia edema hemorrhage atrophy ```

Question 30

presence of mononuclear phagocytes indicates:

Answer 30

persistent Ag in tissue

Question 31

perivascular dermatitis

Answer 31

- most common type of dermatitis - generic response of skin to injury - suggests hypersensitivity* - aggregates of inflamm. cells around vessels - acute or chronic - often eos present**

Question 32

Culicoides hypersensitivity

Answer 32

- insect bite hypersensitivity | - pruritis, alopecia, acanthosis, hyperpigmentation

Question 33

interface dermatitis

Answer 33

-hydropic degen/apoptosis in basal layer -leuks at interface b/w dermis and epidermis -usually immune-mediated -pigmentary incontinence +/- vesicles -most common path = T cell attack on keratinocytes or melanocytes or BM components -Discoid Lupus in GSD --> erosions, depig, crusting

Question 34

Uveodermatologic Syndrome

Answer 34

- Akitas | - depig, uveitis

Question 35

Vasculitis

Answer 35

- leuks WITHIN walls of capillaries and venules - edema, hemorrhage, necrosis - type III hypersensitivity (immune complex deposition in vessels) - primary bacterial skin dz, bacterial septicemia (ie. Diamond Pig Skin Dz) or systemic infection w/ endotheliotropic orgs. such as Rickettsia - lesions usually on extremities

Question 36

Nodular to Diffuse Dermatitis

Answer 36

- difuse infiltrates of leukocytes in dermis - path: persistence of Ag in tissue stimulate a cell mediated immune response - grossly: multiple papules, nodules +/- ulceration - causes: fungi, acid fast bacteria, parasites, protozoans, oomycetes, algae, idiopathic, FB, neoplasm

Question 37

Vesicular or Pustular Dermatitis

Answer 37

- vesicles of pustules are w/n or below epidermis(subcorneal, suprabasilar, or subepidermal) - marked spongiosis, hydropic or ballooning degen. - enzymatic/immune/mechanical destruction

Question 38

panniculitis

Answer 38

- SC fat is focus of inflamm. - gross: papules, nodules - histo: inflamm. of subcutis; nodular to diffuse - causes (same as nodular to diffuse): fungi, acid fast bacteria, parasites, protozoans, oomycetes, algae, idiopathic, FB, neoplasm, + pancreatitis

Question 39

Atrophic dermatoses

Answer 39

- symmetric hypotrichosis, thin skin - comedones, telangiectasia, hyperpigmentation - focal atrophic dermatosis - partical ischemia - hormonal imbalance: hyperadrenocorticism, hypothyroidism, sex hormone imbalance - ischemia if focal