Pemphigus

From Cat
Crusted pinna in a 5-year-old Domestic shorthair cat with pemphigus foliaceus. Courtesy Dr Jim Euclid
Cat above, close-up of facial lesions. Courtesy Dr Jim Euclid

Pemphigus is a cutaneous auto-immune skin disease which most commonly occurs in middle aged to older cats[1] and is characterized by pustular and crusted lesions commonly observed on the ears, nasal planum, periocular area, chin, and paws[2].

The most common form of this disease in cats is pemphigus foliaceus, but a number of variants have been reported, including pemphigus vulgaris (which involves deeper dermal layers) and focal acantholytic dyskeratosis (more superficial and thought to be a version of Darier's disease in humans)[3].

The condition is caused by production of 'self' antigens against keratinocytes (skin cells), specifically the intercellular cement (glycocalyx) of the stratified squamous epithelium. When autoantibodies bind to the glycocalyx, a series of enzymatic reactions occur that destroy the adhesions of the epidermal cells to one another[4].

The loss of intercellular cohesion leads to acantholysis and vesicle formation. The prematurely keratinised epidermal cells are shed into the vesicle in either singlets or rafts of cells commonly referred to as acantholytic cells. The release of inflammatory mediators is chemotactic for neutrophils, which quickly migrate into the vesicle. Clinically, these vesicles appear as pustules, which rupture very easily. The exudate in the vesicles quickly dries and is the source of the crusting so typical of these diseases[5].

There appears to be no breed predilection with these diseases. In one study, 60% of affected cats were domestic shorthair cats[6].

Clinically, this disease results in the formation of pustules and vesicles in the haired and thinly haired areas. Lesions are usually symmetric; nasal crusting accompanied by periocular crusting is highly suggestive of pemphigus[7]. Intact pustules are rarely observed in animals and are most likely to be seen in the inner pinnae.

Affected cats are often depressed and anorectic and may have a marked peripheral lymphadenopathy, alopecia, paronychia, recurrent otitis externa and pruritus (in about 80% of cases)[8][9].

Diagnosis is readily established on histological examination of skin biopsies, showing subcorneal pustules with nondegenerate neutrophils and acantholytic keratinocytes[10].

Skin swabs and skin cultures are recommended to ascertain any secondary bacterial, fungal or viral involvement.

A differential diagnosis would include external parasites (Cheyletiella spp, Notoedres spp, Demodex spp, Sarcoptes spp), ringworm, Malassezia spp yeast, atopy, paraneoplastic disorders[11] and leishmaniasis[12].

Treatment of pemphigus can be frustrating. Many cats may be refractory to antimicrobial therapy and corticosteroids, although a trial therapy should be commenced with prednisolone 6 mg/kg daily, possibly combined with cephalosporins such as cephalexin or cefovecin. In outdoor cats, mosquito-bite hypersensitivity may exacerbate clinical lesions and it recomended to limit outdoor exposure as much as possible. Additionally, a one-month elimination diet should be considered to exclude dietary allergy as an exacerbating component of the condition.

Cats which are non-responsive to therapy or show worsening clinical signs will require immunomodulatory dose of chlorambucil or cyclosporin[13].

The prognosis for cats with pemphigus diseases is good with respect to quality of life, but may require life-long pharmacological therapy[14][15].

References

  1. Barrs VR et al (2003) Pemphigus foliaceus. J Small Anim Pract 44(6):251, 286-7
  2. Peterson A & McKay L (2010) Applied dermatology-crusty cats: feline pemphigus foliaceus. Compend Contin Educ Vet 32(5):E1-E4
  3. Ackerman, AB (1972) Focal Acantholytic Dyskeratosis. Arch Dermatol 106(5):702-706
  4. Miragliotta V et al (2005) Immunohistochemical analysis of the distribution of desmoglein 1 and 2 in the skin of dogs and cats. Am J Vet Res 66(11):1931-1935
  5. Olivry T (2006) A review of autoimmune skin diseases in domestic animals: I - superficial pemphigus. Vet Dermatol 17(5):291-305
  6. Preziosi, DE et al (2003) Feline pemphigus foliaceous: a retrospective analysis of 57 cases. Vet Dermatol 14(6):313
  7. Favrot C (2010) Skin lesions and their distribution in the cat: lessons to be drawn. Schweiz Arch Tierheilkd 152(3):115-119
  8. Griffin, CE (1991) Recognizing and treating pemphigus foliaceous in cats. Vet Med 86:513-516
  9. Greek JS (1993) Feline pemphigus foliaceous: a retrospective study of 23 cases. Proc 8th Ann AVD/ACVD meeting, San Diego, California
  10. Manning, TO et al (1982) Pemphigus foliaceous in the feline: seven case reports and discussion. J Am Anim Hosp Assoc 183:433-443
  11. Turek MM (2003) Cutaneous paraneoplastic syndromes in dogs and cats: a review of the literature. Vet Dermatol 14(6):279-296
  12. Rüfenacht S et al (2005) Two cases of feline leishmaniosis in Switzerland. Vet Rec 156(17):542-545
  13. Irwin KE et al (2012) Use of modified ciclosporin in the management of feline pemphigus foliaceus: a retrospective analysis. Vet Dermatol 23(5):403
  14. Peterson A & McKay L (2010) Applied dermatology-crusty cats: feline pemphigus foliaceus. Compend Contin Educ Vet 32(5):E1-E4
  15. Mehta JN, Martin AG (2000). A case of pemphigus vulgaris improved by cigarette smoking. Arch Dermatol 136:15-7