Dermatology - Autoimmune

sihirlifil's version from 2017-09-25 16:03


Question Answer
Diagnostic plan for crusting/ulcerative skin diseases:History
Physical exam
Skin scrapings (r/o demodex)
Impression smears
Fungal culture
Skin biopsy
CBC/Chem/UA (UTI, problems with meds)
(Can do ANA titers, therapeutic trials)
Problem with diagnosing skin diseases?Many look alike! Need definitive diganosis (biopsy & histopath) before putting on lifelong immunosuppressive therapy
Really common CS for autoimmune?Hypopigmentation
Lots like to extend to planum nasale: ulcerated, crusted, lose cobblestone appearance
Something all immune diseases are exacerbated by?UV light! Need to turn the dog into a vampire and keep them out of the sunlight
Pemphigus foliaceus: signalment?Middle aged-older dogs
Akita, chow chow
Pemphigus foliaceus: pathogenesis?Autoantibodies agains desmosomal proteins in SPINOUS CELL LAYER
Autoantibody binds to antigen (desmoglein), antibody is internalized, release of keratinocyte proteolytic enzyme into extracellular space, hydrolysis of adhesion molecules, intraepidermal acantholysis and pustule formation
T/F Acantholysis always means pemphigusFalse- severe pyodermas can also cause acantholytic cells (treat then biopsy)
Primary lesion of pemphigus foliaceous:Subcornual pustule (filled with neutrophils, rupture easily)
Turns to crust, epidermal collarette
Important to remember about bacteria + acantholysis:Clear infection first! Can't tell if autoimmune or bacterial cause otherwise
Pemphigus foliaceous neutrophils are...Happy! Not toxic
A pemphigus foliaceous Diffquik slide looks likeBig round cells, centered nucleus, acantholytic cells are bigger than neutrophils (like massive)
Best thing to biopsy for PF?Intact pustule (if you can't, send crust)
Secondary lesions of pemphigus foliaceous:Crust, epidermal collarette
Distribution of pemphigus foliaceous?*Planum nasale, foot pads sloughing, ear pinna (not margins!), generally multifocal
Causes of pemphigus foliaceous?May be induced by ANY systemic or topical medication (drug reaction)
Diagnosis of PF:Histopathology (full thickness biopsy)
Lab bloodwork
How to biopsy for PF?Nose: Anesthetize, punch biopsy, suture (gushes blood)
Footpad: DON'T! Doesn't heal well. Can do soft tissue on side of foot pad
You should never biopsy what kind of tissue?Horny layer e.g. footpads
Ddx PF from scabies based on distribution:Scabies likes ear margin, PF likes whole ear
Treatment for pemphigus foliaceous in dogPrednisolone/prednisone (HUGE DOSE) until remission, then taper dose and monitor Chem/UA
Cyclosporine: takes more time to be effective
Azathiaprine: hepatotoxic
Avoid UV
How can you use cyclosporine in combo to tx PF more effectively?Start with Pred & cyclo together, then taper Pred first when remission. Taper cyclo later (less severe SEffx)
When would you use azathiaprine for PF?If no remission with Pred/Cyclosporine; extreme PU/PD
Prognosis of PFGuarded to Very good
What affects the prognosis of PF?Side effects of medications
Cost of treatment
Cost of monitoring
Owner effort
Drug-induced side effects
Feline PF: what does it look like?Pustules rare
Generalized crusting
Recurrent paronychia (inflammation of nail beds)
Affected nipples
Extra thing you have to do when testing for PF in cats?Tell the lab you're suspecting PF! Cat's don't make a lot of acantholytic cells, histopath can miss dx
T/F Cats can be cured of PFTrue!
Treatment options for feline PFPrednisolone
Chlorambucil ($$$)
Why do cats get prednisOLONE?Can't convert prednisone to prednisolone... so just give them prednisolone to start with
Who else can get PF?Horses, goats
Pemphigus Erythematosus: 'cross-over disease' between what?PF & Lupus erythematosus
Dx by biopsy & histopath
Pemphigus vulgaris: common or not?RARE
Pemphigus vulgaris: CSVesicles & ulcers of mostly mucosal surfaces
Pemphigus vulgaris: prognosisPoor
Characteristic micro lesions of pemphigus vulgaris:Tombstone cells from basal cells sloughing
Sub-basilar clefting, fluid-forming vesicles, DEEPER than PF pustules
What kind of cells does pemphigus vulgaris affect?Basal cells (attached to basement membrane)
(Memory trick for PF/Vulgaris lesions)(P = pustules, V = vesicles)
Diseases that cause vesicles: DdxSystemic lupus
Pemphigus vulgaris
Bullous pemphigoid
Drug eruption
How to biopsy for pemphigus vulgaris:Use scalpel blade to keep vesicle intact, go across long axis of lesion (surgical ellipse), get transition from normal to abnormal skin
Treatment of pemphigus vulgarisSteroids! Aggressive doses
CHG rinses in mouth for secondary infections
Systemic lupus erythematosus (SLE): does it exist?No? lol
Signs of SLE (lesions & systemic):Ulcerations/crusts/vesicles
How to diagnose SLE:Skin biopsy
ANA titers (antinuclear antibody- worthless)
Joint tap/biopsy
Rule out everything else
Discoid lupus erythematosus (DLE) simple termsBenign SLE, skin only
DLE: common or rare?Very common in dogs
DLE: distributionPlanum nasale- can be confined here only
Loss of cobblestone appearance, hypopigmentation (permanent!)
Erosions, ulcers
What must you include in your diagnostics for DLE?Bloodwork (need to rule out SLE) (so no anemia, thrombocytopenia, proteinuria, etc etc like in SLE)
Diagnosis of DLE made by Biopsy
Treatment of DLEAvoid UV light! only let out at night
Steroids until remission, then lowest dose possible
Doxycycline & Niacinamide combo
Vitamin E?
How do doxycycline & niacinamide work? (for what disease)Synergistic and steroid-sparing for DLE
Can take a long time to effects, so start steroids at the same time then decrease the dose
Prognosis of DLEGood to guarded

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