Ischemic Dermatopathy

Question 1

What is ischemic dermatopathy?

Answer 1

syndrome that results from loss of blood supply from either vasculitis or vasculopathy, “cell-poor vasculitis” (dermatopathologists)

Question 2

Forms of ischemic dermatopathy

Answer 2

post-rabies vaccination scarring, alopecia, and dermatomyositis, similar histologic cell-poor vasculitis changes seen with familial German shepherd dog vasculopathy, some “lupoid” dermatoses, and the disease in greyhounds

Question 3

Five forms of ischemic dermatopathy

Answer 3

1. familial predisposed dermatomyositis
2. juvenile-onset dermatomyositis in non familial recognized breeds
3. post-rabies vaccination panniculitis
4. generalized vaccine-induced ischemic dermatopathy
5. adult-onset ischemic dermatopathy lesions with no temporal association with vaccines

Question 4

Etiology of ischemic dermatopathy

Answer 4

vascular disease is relatively mild or more subtle in onset or severity, leading to tissue hypoxia; leading to follicular, dermal, and epidermal changes without the more typical vascular changes of hemorrhage, edema, and necrosis

Question 5

Lesions of less severe ischemic dermatopathy

Answer 5

scarring alopecia, shiny scaly skin, and comedones

Question 6

Vaccine-associated ischemic dermatopathy

Answer 6

2-8 months after vaccination, various combinations of plaques, nodules, alopecia, scale, erosions, ulcers, crusts, hyperpigmentation, and scarring

Question 7

Locations of vaccine-associated ischemic dermatopathy

Answer 7

may occur at site of vaccination, pinnae (usually the apex and often the concave surface especially at pinnal margins), face, paw pads, tip of tail, periocular region, and over bony prominences, erosions and ulcers may be seen on the tongue; may have associated atrophic myopathy

Question 8

Differentials for ischemic dermatopathy with linear vascular pattern with ecchymosis or petechia

Answer 8

coagulopathy, SLE, cold agglutinin disease, frost-bite, DIC, and lymphoreticular neoplasia

Question 9

Differentials for ischemic dermatopathy with acute necrotic lesions and ulceration

Answer 9

sub epidermal bullous diseases, burns, deep pyoderma

Question 10

Differentials for ischemic dermatopathy with predominantly urticarial lesions

Answer 10

hypersensitivity disorders not associated with vasculitis

Question 11

Differentials for ischemic dermatopathy with early focal lesions

Answer 11

Demodex, dermatophytosis, DLE, dermatomyositis

Question 12

Infectious diseases that can lead to vasculitis and ischemic dermatopathy

Answer 12

Babes, Echrlichia/Anaplasma, Bartonella, Rickettsia rickettsii, Borrelia burgdorferi, and Leishmania infantum; identification does not prove causation but would be suspicious and warrant therapy

Question 13

Sources of septic vasculitis

Answer 13

deep pyoderma, cellulitis, bacterial endocarditis

Question 14

Thrombus formation in ischemic dermatopathy

Answer 14

thrombus formation, fibrin in the thrombus is broken down, results in formation of D-dimers (fibrin degradation products); mAb based assay detects D-dimers in the blood: 15 dogs with vasculitis had thrombi present in skin biopsy and D-dimer levels greater than 500ng/mL (specificity 100%, sensitivity 64%), 11 dogs had no thrombi detected and variable D-dimer levels; fibrinogen levels elevated >normal/287mg/dL in all vasculitis dogs

Question 15

IFA or IHC in vasculitis

Answer 15

not needed or useful for diagnosis bc best done within 4 hours of lesion formation and no later than 24 hours; may demonstrate immunoglobulin, complement, or both in vessel walls and occasionally at BMZ in both neutrophilic and lymphocytic forms of cutaneous vasculitis

Question 16

Clinical course of vasculitis varies depending on syndrome and cause

Answer 16

single episode lasting a few weeks, or may be chronic and lifelong or recurrent; outcome depends on extent of organ involvement (particularly renal and neurologic) and underlying or precipitating factors; once immune complexes and immune system stimulation, even controlling the primary cause may not immediately resolve the vasculitis

Question 17

Treatment of ischemic dermatopathy

Answer 17

underlying or precipitating factor treatment + pentoxifylline, glucocorticoids with or without azathioprine, cyclosporine, in combination, Vitamin E as an adjunct, may be stopped after 4-6 months or continued lifelong

Question 18

Proliferative thrombovascular necrosis of the pinnae

Answer 18

slowly progressive and usually unresponsive to most medical therapies, though some respond to pentoxifylline, if that is ineffective tx of choice is partial surgical removal of the pinna, relapses more common when attempt to leave tissue

Question 19

Focal cutaneous vasculitis and alopecia subsequent to injections

Answer 19

may respond to pentoxifylline (up to 75% reduction in lesion size) or may be treated by complete surgical excision, or occasionally spontaneously resolve; topical tacrolimus can be effective in some cases, logical NOT to repeat the vaccine unless required by law due to possibility of repeat reactions

Question 20

Solar vasculopathy

Answer 20

minimize UV exposure (both UVB and UVA though UVB most likely the more problematic), keep pet indoors and minimize sun exposure through glass, use of sunscreen 30spf or greater with UVA blockers and solar-protective garments