L61: distribution of dermatology patterns pt. 1

what the patterns of distribution?

1. focal

2. multi-focal

3. generalized

focal distribution

lesion is limited to one area

focally extensive

spread of lesion locally within the region of the body where it originally appeared

multi-focal

one or more focal lesions develop elsewhere on the body

generalized distribtution

lesions are extensive and cover most of the body

what are examples of generalized lesions?

1. allergic dermatitis

2. ectoparasites

what are some examples of focal distributions?

1. fungal infection

2. traumatic wounds, hot spots

3. localized demodicosis

4. injection-site reactions, pressure sores

symmetrical lesions typically arise from…

internal causes

asymmetrical lesion distribution typically arises from…

external causes

what categories do you think of when thinking of causes for symmetric lesions?

1. allergies

2. endocrine

3. metabolic

4. immune-mediated

what categories do you think of for causes of asymmetric pattern distribution?

1. infectious

2. neoplasia

3. trauma

what things cause unilateral otitis externa?

1. foreign body

2. mass (polyp or neoplasia)

what things cause bilateral otits externa?

allergies

what causes generalized symmetric lesion distribution?

allergies

what causes pruritic patterns around the feet or face?

1. atopy

2. food allergy

what causes pruritic pattern around the ears in cats?

otitis externa → parasites

what causes pruritic pattern around the ears in dogs?

otitis externa → allergies

what causes pruritic pattern around the tail?

flea allergy dermatitis

what causes pruritic pattern around the ventral abdomen?

contact dermatitis

where in dogs will lesions from atopic dermatitis appear?

1. paws

2. muzzle

3. axillae

4. inguinal

where in dogs will lesions from flea allergy dermatitis appear?

“pants zone”

where will lesions from cushing’s appear in dogs?

flank

where will lesions from eosinophilic granuloma complexes appear in cats?

1. lips

2. thighs

3. abdomen

where will lesions form miliary dermatitis appear in cats?

trunk

where will lesions appear from flea allergy dermatitis in cats?

1. head and neck

2. pants zone

what are the categories for infectious skin disease?

1. bacterial

2. fungal

3. viral

4. parasitic

what are the key diagnostic tools for bacterial skin diseases?

1. cytology

2. culture and susceptibility

what are the superficial bacterial infections?

1. canine superficial pyoderma

2. impetic (“puppy pyoderma”)

3. canine mucocutaneous pyoderma

4. superficial spreading pyoderma (“hot spot”)

what is the infectious agent of canine superficial pyoderma?

staphylococcus pseudintermedius

what gross lesions appear from canine superficial pyoderma?

1. erythema

2. macules

3. papules

4. pustules

5. crust

6. colarettes

what histological features appear with canine superficial pyoderma?

1. inter-epidermal pustules with serocellular crusts

2. superficial suppurative luminal folliculitis

what is the infectious agent of impetigo?

coagulase-positive staphylococcus

what areas are affected on the body from impetigo?

areas of thin coat → abdomen, inguinal, and axillary

how do gross lesions from impetigo appear?

1. erythema

2. macules

3. papules

4. pustules

5. crusts

6. collarettes

what are the histological features of impetigo?

NON-FOLLICULAR subcorneal pustules with serocellular crusting

what is the most common areas affected by canine mucocutaneous pyoderma?

lips and nose

what gross lesions appear from canine mucucutaneous pyoderma?

1. erythema

2. swelling

3. crusting

4. ulceration

5. pigmentation

what histological features are seen with canine mucocutaneous pyoderma?

1. inflammation at dermoepidermal junction

2. pigmentary incontinence

what gross lesions appear IN ORDER OF OCCURENCE with superficial spreading pyoderma?

1. erythematous macules/pustules

2. transient papules

3. epidermal collarettes, crusts, and alopecia

what histology features occur IN ORDER for superficial spreading pyoderma?

1. early spongiosis / epidermal pustules

2. crusts with debris/cocci and perivascular inflammation in the dermis

what is the area of infection for deep pyoderma (deep bacterial infections)?

deep hair follicle, dermis, and subcutis

what is the MOST COMMON infectious agent for deep pyoderma?

staphylococcus pseudintermedius

what histology features are seen with deep pyoderma?

1. folliculitis

2. furunculosis → pyrogranulomatous inflammation = typical

3. paniculitis

what are the infectious agents of septicemia?

1. e. coli

2. salmonella

3. klebsiella

4. staphylococcus aureus

what type of dermatological signs appear with septecemia?

CUTANEOUS

1. petechaie

2. ecchymoses

3. purpura

4. necrosis

what type of dermatologic signs appear with streptococcal toxic shock-like syndrome?

SKIN LESIONS

1. rapidly spreading cellulitis

2. necrotizing fascilitis

3. cutaneous hemorrhage

what is the most common cause of subcutaneous abscess in cats?

puncture wounds with subsequent bacterial infections

what gross lesion is associated with subcutaneous abscesses?

draining tracts that then will heal by scarring

what do you have to do to see bacterial granulomatous dermatitis under the microscope?

acid fast staining

1. ziehl-neelsen

2. fite-faraco stain

what is the cause of bacterial granulomatous dermatitis in cats?

mycobacterial lepraemerium (leprosy)

what lesions are seen with bacterial granulomatous dermatitis?

1. cutaneous/subcutaneous nodules

2. ulcerated draining tracts

what are the types of non-mycobacterial granulomas?

1. non-filamentous bacterial granuloma

2. filamentous bacterial granuloma

which non-mycobacterial granuloma creates the “splendore-hoeppli” phenomenon?

non-filamentous bacterial granuloma