Special pathology - dermatology

Question 1

The skin provides a protective barrier against? (4)

Answer 1

fluid loss, microbiologic agents, chemicals, and physical injury

Question 2

A myriad of exogenous and endogenous factors influence the skin how?

Answer 2

gross and microscopic appearance of the skin.

Because the skin can respond to these factors in only a limited number of ways,
different skin disorders may have a similar histologic appearance!

Question 3

A pathologic skin pattern description consists of two parts:

Answer 3

a component of the skin (e.g., epidermis) +
a histologic reaction of that component to injury
(e.g., hyperkeratosis)

= pattern (hyperkeratotic diseases of the epidermis).

Question 4

pansteatitis

Answer 4

or yellow fat disease, is a physiological condition in which the body fat becomes inflamed.

Question 5

callus

Answer 5

Thick, firm, hyperkeratotic, hairless plaque with increased skin folds, wrinkles, or fissures.

In haired skin, follicular plugging and comedones also may develop.

Example: Trauma over bony prominence such as elbow, sternum, or side of digit.

Question 6

COMEDO (pl. COMEDONES)

Answer 6

Plug of stratum corneum and sebum within the lumen of a hair follicle that leads to follicular distention.

Examples: Canine solar (actinic) dermatosis, chin acne, Schnauzer comedo syndrome, hyperadrenocorticism, canine palmar and plantar interdigital cysts

Question 7

CRUST

Answer 7

Dried exudate composed of various components, including fluid, blood, pustular debris, scale, or microorganisms on the skin surface.

Example: Chronic stage of pustular disease such as staphylococcal infection

Question 8

CYST

Answer 8

Cavity lined by epithelium
filled with liquid or semisolid material
located in the dermis or subcutis;
may communicate with surface via a pore.

Examples: Follicular cyst, dermoid cyst, apocrine gland cyst

Question 9

EPIDERMAL COLLARETTE

Answer 9

A thin layer of scale that expands peripherally and forms a ring (arrows).

Examples: Superficial bacterial infection, insect bite, fungal infection

Question 10

EROSION

Answer 10

Partial-thickness loss of epidermis resulting in shallow, moist, glistening depression
(arrows).

Examples: Secondary to vesicle or pustule rupture or secondary to surface trauma

Question 11

EXCORIATION

Answer 11

Shallow, vertically oriented linear break in skin surface (epidermis) (arrows)

Example: Abrasion or scratch

Question 12

skin FISSURE

Answer 12

Deep, vertically oriented linear cleft or break (arrow) from the epidermis into the
dermis.

Examples: Pawpad fissure seen in superficial necrolytic dermatitis, or digital hyperkeratosis

Question 13

LICHENIFICATION

Answer 13

Rough, thickened epidermis secondary to persistent rubbing, scratching, or irritation;
may have increased pigmentation.

Example: Chronic dermatitis

Question 14

MACULE

Answer 14

Flat, circumscribed, nonpalpable area that is a change in the color of the skin, < 1 cm
in diameter.

Examples: Hemorrhage, vitiligo

Question 15

NODULE

Answer 15

Elevated, often firm, circumscribed, solid palpable lesion ≥1 cm in diameter. Often
located in dermis or subcutis.

Examples: Bacterial or fungal infection, infectious or sterile granuloma

Question 16

PAPULE

Answer 16

Elevated, firm, palpable, circumscribed area < 1 cm in diameter (arrows), but may
occur grouped together, may coalesce to form a plaque.

Examples: Insect bite, papilloma, superficial folliculitis

Question 17

PLAQUE

Answer 17

Elevated, usually firm, flat-topped, circumscribed, palpable lesion ≥ 1 cm in diameter, may coalesce to form a larger lesion.

Examples: Calcinosis cutis, reactive histiocytosis, eosinophilic plaque

Question 18

PUSTULE, EPIDERMAL

Answer 18

Circumscribed raised superficial accumulation of purulent fluid within the epidermis
(arrow).

Examples: Bacterial infection, pemphigus foliaceus

Question 19

name 3 causes of skin scales

Answer 19

SCALE
Sheets of cornified cells that horizontally split and separate from underlying
epidermis as irregular, thick or thin, dry or oily fragments, may adhere to hairs.
Variations include silvery, powdery, greasy, gritty, and polygonal.

Examples: Cornification disorders, sebaceous adenitis, ichthyosis

Question 20

Sebaceous adenitis is an

Answer 20

Sebaceous adenitis is an immune-mediated disorder in which an inflammatory process is directed against the sebaceous glands in the skin.

Question 21

ULCER

Answer 21

Full-thickness loss of epidermis and basement membrane, and at least a portion of
the dermis with depression of the exposed surface. May extend into deeper tissue.

Examples: Ischemic lesions resulting from vasculitis, feline herpesvirus dermatitis, feline ulcerative dermatitis syndrome

Question 22

VESICLE AND BULLA

Answer 22

Elevated, circumscribed, horizontal, fluid-filled lesions differentiated by size.Fluid may be
clear, tan, or red (hemorrhagic)

Vesicle: < 1 cm in diameter
Bulla: ≥ 1 cm in diameter (arrows)

Examples: Burn, viral infection

Question 23

diff between a vesicle and a bulla

Answer 23

Vesicle: < 1 cm in diameter
Bulla: ≥ 1 cm in diameter

Question 24

WHEAL

Answer 24

Elevated, irregular-shaped area of dermal edema; solid, usually transient, often pale
centrally with an erythematous rim (arrows)

Examples: Insect bites, urticaria, allergic reaction.

Question 25

Dermatitis

Answer 25

nonspecific term used until the dermatologic history, clinical signs, and physical examination can more precisely define the problem.

Many skin diseases look alike and are differentiated by working through diagnostic flow charts and a process of elimination.

Question 26

The most common dermatologic problems include: (8)

Answer 26

alopecia
erosions and ulcerations

nodules or tumors
nonhealing wounds

odor
otitis

pruritus
scaling and crusting

Question 27

Etiology of Alopecia in Animals

Answer 27

any disease that can affect hair follicles can cause hair loss.

1) congenital or hereditary
2) acquired.
- inflammatory
- noninflammatory.

Question 28

the most common cause of alopecia

Answer 28

Inflammatory acquired alopecia

a disease destroys the hair follicle or shaft, interferes with the growth of hair or wool, or causes the animal discomfort (eg, pain, pruritus), leading to self-trauma and loss of hair.

Question 29

Diseases that can directly cause destruction or damage to the hair shaft or follicle: (5)

Answer 29

Bacterial skin diseases
Dermatophytosis
Demodicosis

Severe inflammatory diseases of the dermis (eg, juvenile cellulitis, deep pyoderma)
Traumatic episodes (eg, burns, radiation)

Question 30

Diseases that commonly cause pruritus or pain: (4)

Answer 30

infectious skin diseases (eg, bacterial pyoderma and dermatophytosis)

ectoparasites

allergic skin diseases (eg, atopic dermatitis, food allergy, contact, insect hypersensitivity)

less commonly- neoplastic skin diseases

Question 31

Pruritus in Animals

Answer 31

an unpleasant sensation within the skin that provokes the desire to scratch

It is the most common dermatologic problem in both small and large animals!

most common cause of pruritus is parasites

Infections are common complications of pruritus.