Derm 14 - more immune Flashcards
Vasculopathic disease
- pathogenesis
- considered to be a type III hypersensitivity (antigen-antibody complexes become trapped
along the basement membrane of vessel walls and activate the complement cascade) or a condition resulting from direct antibody binding to the vessel wall and the release of toxic mediators, leading to a bystander reaction - Regardless of the pathomechanism, it is characterized by blood vessel damage that results in ischemia of the skin and resultant tissue necrosis
Vasculopathic disease risk factors
o drug therapy (e.g. itraconazole at daily doses above 10 mg/Kg)
o malignancy
o infection (viral, bacterial, fungal, rickettsial)
o immune-mediated diseases (e.g. Systemic Lupus erythematosus - SLE) o insect bites and
o food hypersensitivity (urticarial vasculitis).
Vasculopathic disease lesions distribution for different types, and lesion character
- Lesions can be localized, regional, or multifocal to generalized
- Patients may present with crusted or ulcerative macules or patches
<><> - Typically, rabies vaccine induced vasculopathy will present with a well demarcated alopecic, often scaly and hyperpigmented patch at the site of the rabies vaccine
- Urticarial vasculitis may present with erythematous and often pruritic wheals. These patients are often anorexic and lethargic
- Physical examination of patients with thrombovascular pinnal vasculitis will reveal notching of pinnal margins at tip and/or well-demarcated ulcers on the concave aspect of the pinna
- Those with idiopathic vasculitis well-demarcated necrosis and ulceration, particularly at the extremities and pressure points; may include edema, alopecia, or crateriform ulcers on the central aspect of the footpads. Some of these cases could be a rare manifestation of rabies vaccine-induced generalized ischemic dermatopathy
Vasculopathic disease Dx
Diagnosis is based on biopsy
- Multiple skin biopsies for histopathologic evaluation
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- bacterial serologic titers, hypoallergenic dietary trials should be considered
Vasculopathic disease, goal of treatment
- long term treatment options
improve circulation to the affected area, control self-trauma, and suppress the immune reaction while evaluating for the inciting cause.
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Long-term treatment (4-6 months, sometimes indefinitely) is often needed:
- Pentoxifylline > increase RBC deformability
- Some response has been noted to extra label use of oclacitinib
- In some cases, Tetracycline and Niacinamide
- Refractory cases may need to be treated with prednisone or prednisolone
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- Once control is achieved flares or “stubborn spots” can be treated with Tacrolimus 0.1% topically
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Thrombovascular pinnal vasculitis has a variable response (may wax and wane) and some cases do better with surgical management
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Patients with localized lesions of Rabies induced vasculitis should not be revaccinated whenever possible
> If vaccines are necessary, vaccinate dogs IM. An increased risk of an anaphylactic reaction has been suggested.
Vasculopathic disease treatment success, prognosis
Regardless of the treatment, some cases resolve, whereas others are chronic or recurrent. Damage to other organs (renal, neurologic) will also affect prognosis, of course
Mucous membrane pemphigoid
- how common? what type of disease?
- signalment
- progression
- lesions, clinical signs
- the most common autoimmune blistering disease in the dog, although it is quite rare
- Middle aged to late adult patients are most commonly affected and German Shepherds appear to be overrepresented
- In some cases, this can be a very slowly progressive disease, with the presence of skin lesions before
presentation as short as 2 weeks and as long as 5 years with a median of 4.5 months
<><><><> - Lesions often first arise in the oral cavity and on or around the nose but progress to affect the lips, eyes,
genitalia, concave pinnae and/or the perianal area. Non-mucosal lesions have also been reported
(footpads and around the claws). - These patients do not appear to be systemically ill
Mucous membrane pemphigoid Dx
The diagnosis is based on biopsy
o Subepithelial vesiculation is noted
o When PAS or immunohistochemical staining for collagen IV were performed, they revealed that
clefting always arose above the lamina densa of the epidermal basement membrane zone
Mucous membrane pemphigoid prognosis, treatment
The prognosis is fair to good for MMP.
Tetracycline/Niacinamide has been effective
Others are treated with prednisone with or without azathioprine
There was a response to off label oclacitinib reported
Erythema Multiforme
- how common, what does it look like?
- canine trigger?
- lesions / presentation
- an uncommon disease that presents as a rapid onset inflammatory skin reaction
- most commonly associated with a drug reaction in the dog
- infections, diet, neoplasia have also been implicated
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while the presentation is variable, lesions may appear as: - erythematous macules to patches that spread peripherally and clear centrally leading to annular or arciform patterns
- small papules may be present
- mucosal lesions may present as vesicles, bullae or ulcers
- the ventrum (axillae and groin), mucocutaneous junctions, oral cavity , pinnae and pads may be
affected
Erythema Multiforme Dx
biopsy; apoptosis is typically noted at all epidermal layers
Erythema Multiforme Tx
- rigid investigation for an underlying trigger, including food as identification and removal of the trigger may lead to resolution as quickly as 3 weeks
> many cases idiopathic
<><> - Treatments with glucocorticoids, azathioprine and cyclosporine have been used and there are anecdotal reports of response to pentoxifylline
- intravenous immunoglobulin therapy may be beneficial but there is a risk of serious side effects and it is very difficult to obtain
- severe cases > supportive care
Juvenile cellulitis
- also known as?
- lesions? distribution?
- clinical presentation
- treatment?
- puppy strangles
- sterile granulomatous dermatitis and lymphadenitis
- granulomatous and pustular disorder of the face, pinnae, and submandibular lymph nodes, usually of puppies
- Acutely swollen face, especially the eyelids, lips, and muzzle
- Affected areas are edematous, and lesions typically progress to draining fistulae and crust
- striking submandubular lymphadenopathy
- papules and pustules develop rapidly
- Lesions are most common on the lips, muzzle, chin,
bridge of the nose, and periocular area - Otitis externa is common, and pinnae are frequently
thickened and edematous - firm to flucuant subcutaneous nodules that may be painful or fistulaed may be present
<><> - respond well to glucocorticoids, suggesting an underlying immune dysfunction
juvenile cellulitis signalment
- usually puppies between 3 weeks and 4 months, but can be older
- Although Retrievers,dachshunds, and gordon setters appear to be predisposed, others can be affected
juvenile cellulitis cytology
- pyogranulomatous inflammation with no microorganisms (unless secondary infection)
- carefully performed cultures are negative
