Derm 3: Immune-mediated, cutaneous crusting/misc skin disorders, nodular dermatoses (E2) Flashcards
How are immune-mediated skin disorders diagnosed?
Histopathology of multiple biopsies
+/- IHC
Label these layers
A: Stratum corneum
B: Stratum lucidum
C: Stratum granulosum
D: Stratum spinosum
E: Stratum basale
F: Dermis
Cats Love Going Sun Bathing (Daily)
What are the 2 first-choice immunosuppresive drugs to treat immune-mediated skin disorders?
Glucocorticoids
Cyclosporine A
_______ ______ is a vesiculobullous to pustular group of disorders of the skin or mucus membranes characterised by the loss of cohesion between keratinocytes, known as _______.
Pemphigus complex
Acantholysis
What is the benign form of pemphigus? Which breeds are predisposed? What are the classical clinical signs and where do they occur?
Pemphigus erythematosus
Collies and GSD
Erythema, pusular dermatitis of face and ears
Transient lesions (oozing crusts, scales, alopecia, eorsions, epidermal collarettes)
Depigmentation of nose
What are the differential diagnoses for pemphigus erythematosus?
Bacterial folliculitis
Dermatophytosis
Demodicosis
Facial pemphigus foliaceus
DLE
SLE
Dermatomycositis
Leishmania
Zinc responsive dermatitis
Drug rxn
T?F: Sun avoidance and systemic glucocorticoids or cyclosporin are the accepted treatments for pemphigus erythematosus.
False, sun avoidance and TOPICAL glucocorticoids or cyclosporine
The most common immune-mediated condition is ______ ________. The major antigen is the adhesion molecule ________.
Pemphigus foliaceus
Desmoglein 1
Where are lesions typically found in a dog with pemphigus foliaceus? Cats?
Dogs: Starts at face and ears, commonly involves feet, clawbeds, footpads and groin
Cats: Nail beds, nipples
Also nasal depigmentation
Where does cellular infiltration in pemphigus foliaceus occur? Which skin layers loss adhesion in pemphigus vulgaris and bullous pemphigoid?
Foliaceus: Between stratum corneum and granulosum
Vulgaris: Stratum spinosum and basale
Bullous pemphigoid: Epidermis and dermis
Where is the most common lesion location for an animal with pemphigus vulgaris? Where are cutaneous lesions common? What is the claw bed lesion?
Which other condition causes lesions in these areas?
Oral cavity (75-90% have lesions in mouth)
Axillae and groin
Ulcerative parochyia (clawbeds)
Bullous pemphigoid
What drugs are used to treat pemphigus vulgaris?
High dose prednisolone an azathioprine PO
Cats: Chlorambucil
What condition involves autoantibodies against antigens of the basal cell hemidesmosomes of the skin and mucosa? What drugs predispose to this condition?
Bullous pemphigoid
Sulphonamides, Penicillins, Furosemide
Which cells predominate in lupus erythematosus? Which specifically in DLE and SLE?
T-cells
DLE: T-Helper
SLE: T-Suppressor
Damage to which cells activate T cells in DLE and what do the damaged cells have high levels of? What type of antibody is often formed?
Keratinocytes
ANA (Anti-nuclear antibody)
IgM
Pemphigus vulgaris can involve antibodies reacting against a certain molecule, what is this molecule and in what species is it found?
Desmoglein 3
(“V” (vulgaris) rhymes with “Three”)
Dogs
What are some breeds predisposed to DLE? What are the lesions?
Collies, GSDs
Shetland sheepdogs, Siberian huskies, Brittany spaniels, German shorthaired pointers
Lesions: Depigmentation, erythema, scaling of nose, progress to erosions, ulceration and crusting
What part of the skin is thickened in DLE due to cellular infiltration?
Basement membrane
What clinical signs occur in dogs with SLE? Is there a sex prediliction in dogs or cats?
Fever
Polyarthritis
Proteinuria
Alopecia, erythema, vesciculobullous to ulcerative lesions
Dogs- males over-represented
Cats- no sex prediliction
Your canine patient with SLE has developed glomerulonephritis. What do you expect and what is the prognosis?
Progressive renal failue
Poor prognosis
What is the drug that most commonly causes cutaneous adverse drug reactions? What does it mean if this reaction is idiosyncratic?
Penicillin
Idiosyncratic: unpredictable, dose-independent, related to host immune system (opposite of predictable reaction which is drug- and dose-dependent)
Your patient acutely develops erythematous macules which have spread peripherally and cleared centrally. There are also urticarial plaques. Lesions are primarily on the ventrum, axillae, and groin. What type of degeneration is occuring and what is this condition called? How is it treated?
Hydropic degeneration (all levels of epidermis)
Erythema multiforme
Tx: Eliminate trigger, wait for it to spontaneously regress.
What will a skin biospy from an animal with toxic epidermal necrolysis reveal?
Full-thickness epidermal nercolysis
Minimal inflammation
What do the lesions that characterize vasculitis look like and where do they occur?
Purpura, wheals, edema, papules, plaques, nodules, alopecia, scarring, necrosis and ulceration (punched out ulcers)
Extremities- paws, pinnae, lips, tail, scrotum, oral mucosa
Other than determining the underlying disease, what drugs are used to treat vasculitis?
Pentoxifylline (increases erythrocyte flexibility and reduces inflammation.)
Immunosuppressive and immunimodulatory drugs
What 3 conditions commonly cause seborrhea, crusts or scales WITH pruritus? What if there is no pruritus?
Allergies (FAD, AD, FA)
Parasites (sarcoptes, cheyletiella)
Infections (pyoderma, malassezia) *+/- pruritus*
No pruritus: demodicosis, dermatophytosis, endocrine diseases (hypothryoid, HAC, alopecia X)
What is the difference between syndrome 1 and syndrome 2 of zinc-responsive dermatosis?
Syndrome 1 is decreased capacity to absorb zinc from GIT
Syndrome 2 is RARE and caused by dietary deficiency
What breeds get breed-related zinc-responsive dermatosis?
Siberian huskies
Alaskan Malamutes
Bull terriers
What clinical signs are associated with zinc-responsive dermatosis? Where do they occur and when do they start?
Pruiritus and scales/crusts
Mouth, chin, eyes, ears, elbows, pressure points, scrotum, prepuce, vulva
Hyperkeratotic foodpads
Signs begin around 1-3yrs of age
What are some speculated causes of sebaceous adenitis?
Inherited sebaceous gland destruction
Cell-mediated immunological rxn
Defect in keratinization/obstruction of sebaceous ducts
Abnormal lipid metabolism
What clinical signs occur in dogs with sebaceous adenitits? Cats?
Dogs: Bilaterally symmetrical alopecia and/or dry brittle coat, ‘moth eaten’ look, silvery dandruff, ceruminous ottitis externa, some get rat tail, non-pruritic
Cats: multifocal annular lesions of scale, crust, brokem hair casts, alopecia (starts around head and moves caudally)
What is primary ideopathic seborrhea? What does it cause?
Vitamin A responsive dermatosis - hereditary disorder of keratinization that starts weeks to months after birth as mild scaling which worsens with age
Causes abnormal cornification and desquamation with prominent follicular casts and ceruminous otitis
Categorize these as either moisturizing or degreasing (shampoos):
Chlorheiderm
Allergroom
Oxydex
Selsun Blue
Epi-soothe
Moisturizing:
Chlorheiderm
Allergroom
Epi-soothe
Degreasing:
Oxydex
Selsun Blue
A schnauzer presents to you with comodones covering its back. The eruptions are sharp crusted papular lesions that span from the neck to the base of the tail. What inherited disorder could this be and what seocndary lesions do you expect?
Schnauzer Comedo Syndrome
Folliculitis and furunculosis
(Inherited dysplasia of hair follicle)
A dachshund presents with scaly lesions around the edges of the ears. You note follicular casts and alopecia on most of the ears. Considering the breed, what condition could this be? How would you treat it if it was mild? What if the condition is complicated by other organisms?
Ear Margin Dermatosis
Mild: moisturizers, sulfur salicylic acid shampoo, topical glucocorticoid cream
Complicated: Pentoxifylline
A 10 year old Yorkie presents with hyperkeratotic, crusty, cracking footpads. The lesions are also infected with yeast. What diseases do you fear may develop in this dog? What condition does the dog have?
Hepatic or pancreatic disease
Superficial necrolytic dermatitis
What blood chemistry changes can be caused by SND? What unique liver pattern may you see on US?
Increased ALT, ALP, AST, Bilirubin
Decreased BUN, ALB, GLU
US Liver: Honey-comb pattern
What is the behavioral dermatosis caused by self-induced trauma of the skin through excessive licking and chewing?
Acral lick granuloma
What lupus-like disease resuts in acute claw loss? In what species is this the most common nail disorder?
Idiopathic Lupoid Onychodystrophy
Cats
What sample would you submit for histopathology if you suspect idiopathic lupoid onychodystrophy? Aside from treating secondary infections, what is used to treat this condition? If that doesn’t work, what can you try next?
Amputated dew claw (best) or P3
EFAs and vit E
Niacinamide/Tetracycline and steroids
What should you include when creating a cytology to diagnose a nodule?
FNA of nodule and LN draining the area
Make impression smear of discharge or ulcerated lesion
T/F: Papillomatosis usually causes solitary lesions.
True
You sample a nodule and find that it is made up of necrotic fat. What is this called and what does it indicate?
Nodular panniculitis or steatitis
Indicates systemic disease
How does a histocytoma usually look and how is it diagnosed?
Round, alopecic, red
Aspiration cytology
What histocytic proliferative disease causes single to multiple non-pruritic firm papules, nodules or plaques on the legs, feet and face of cats?
Feline Proliferative Histiocytosis
A 5 year old GSD presents with multiple cutaneous nodules consisting of mature collagen hyperplasia. What is the disorder and what underlying condition do you fear may be affecting the dog as well?
Nodular dermatofibrosis
Renal disease
What disorder to which young Gordon Setters, Golden Retreivers, and Dachshunds are prediposed, causes acute, non-pruritic, pyoderma-like clinical signs, as well as facial and submandibular swelling? What are the key rule-outs?
Juvenile Cellulitis/Puppy strangles
R/O: Demodex, deep bacterial pyoderma, angioedema
Should juvenile cellulitis be treated and if so with what?
Yes, mjst be treated or could cause scarring or death
Pred 2mg/kg SID q1-4 weeks (remission) then EOD q2-3weeks
What do you call an epithelial lined cavitiy with either solid or fluid material within?
Cyst
What causes a sebaceous cyst and how is it treated?
Hair follicle or skin pore gets blocked by dirt, debris, scar tissue or infection
Excision is curative
T/F: Keratin inclusion cysts should be manually expressed to hasten resolution.
False, can cause subepidermal rupture and subsequent furunculosis (can just monitor or remove it causing problems)
What is attracted to the smell of urine and feces and causes myiasis? What is the predilication site?
Cobylobia anthrophaga (Tumbu/Mango fly)
Tail base, ventral abdomen
Where does myiasis caused by biting flies usually occur and how do the lesions look?
Tips of ears
Erythema, bleeding, oozing, crusting lesions
How is fly bite dermatitis/myiasis treated generally and if caused by Tambu flies or mosquitos? What if there are maggots?
Topical fly repellants
Tambu: Cover breathing holes with vasoline, gently squeeze out if problematic but avoid damaging larvae
Mosquito: avoidance, ectoparastitic drugs
Maggots: clip and clean, flush out maggots, extra-label ivermectin
