JPC SYSTEMIC PATHOLOGY
Signalment (JPC 2614951): Nine-year-old domestic shorthair cat
HISTORY: This cat had a swollen, soft, discolored footpad.
HISTOPATHOLOGIC DESCRIPTION: Skin, footpad: Multifocally infiltrating the dermis, separating and surrounding footpad adipose tissue and collagen bundles, and surrounding adjacent adnexa are numerous plasma cells and fewer lymphocytes and neutrophils. Frequently, plasma cells are packed with globular eosinophilic intracytoplasmic vacuoles (Russell bodies within Mott cells). There is increased clear space separating collagen fibers and ectatic lymphatics (edema) which occasionally contain aggregates of lymphocytes. There is minimal multifocal epidermal spongiosis characterized by increased intercellular clear space and accentuation of intercellular bridges.
MORPHOLOGIC DIAGNOSIS: Skin, footpad: Pododermatitis, plasmacytic, diffuse, marked, domestic shorthair, feline.
CONDITION: Feline plasma cell pododermatitis
- Rare skin disease of cats; rarer in dogs
- No breed predilection, typically affects cats 6-months to 12-years of age, possibly neutered males are predisposed
- A minority of affected cats also have plasma cell stomatitis, immune-mediated glomerulonephritis, or renal amyloidosis; may have concurrent indolent ulcers or eosinophilic granulomas
- Both medical and surgical treatment is curative
- Recent reports often document a concurrent FIV infection
- Pathogenesis is unknown
- Possibly immune-mediated because there is:
- Persistent hypergammaglobulinemia
- Plasma cell infiltrate
- Beneficial response to glucocorticoid treatment
- Recurrence in warm weather supports an allergenic origin
- Immunohistochemistry and PCR studies have not revealed any infectious agents
TYPICAL CLINICAL FINDINGS:
- Non-painful unless there is ulceration
TYPICAL GROSS FINDINGS:
- Commonly affects multiple pads on multiple feet; larger metacarpal and metatarsal pads most commonly affected
- Uniform swelling that does not disturb normal pad architecture
- Web-like cross-hatched appearance
- Ulceration is common
TYPICAL LIGHT MICROSCOPIC FINDINGS:
- Diffuse dermal plasma cell infiltrate obscures normal architecture
- Plasma cells containing Russell bodies (Mott cells)
- Epidermal acanthosis, erosion, or ulceration
- Variable number of neutrophils independent of ulceration
ADDITIONAL DIAGNOSTIC TESTS:
- With classic clinical appearance and aspiration cytology reveals predominately plasma cells, biopsy may not be necessary
- Immunoelectrophoresis - hypergammaglobulinemia
- Eosinophilic granuloma: Features eosinophils and collagen degradation; will not involve multiple foot pads
- Neoplasia: Eccrine carcinoma, metastatic pulmonary bronchioloalveolar carcinoma (multiple feet), plasmacytoma (typically only one foot)
- Infectious or sterile granuloma
- Insect bites
- Bettenay SV, Lappin MR, Meuller. An immunohistochemical and polymerase chain reaction evaluation of feline plasmacytic pododermatitis. Vet Pathol. 2007;44(1):80-83
- Breathnach, R.M., Baker, K.P., Quinn, P.J., McGeady, T.A., Aherne, C.M., and Jones, B.R. Clinical, immunological and histopathological findings in a subpopulation of dogs with pododermatitis. Veterinary Dermatology. 2005:16:364–372.
- Dias Pereira P. Faustino, AMR. Feline plasma cell pododermatitis: a study of 8 cases. Veterinary Dermatology. 2003:14: 333–337.
- Gross TL, Ihrke PJ, Walder EJ, Affolter VK. Diseases of the dermis. In: Skin Diseases of the Dog and Cat. 2nd ed. Ames, IA: Blackwell; 2005:363-364.
- Guaguere E, Hubert B, Delabre C. Feline pododermatoses. Vet Dermatol. 1992;3(1):1-12.
- Mauldin EA, Peters-Kennedy J. Integumentary system. In: Maxie MG Jubb, Kennedy,and Palmer’s Pathology of Domestic Animals. Vol 1. 6th ed. Philadelphia, PA: Elsevier Ltd. 2016:613-614.
- Pereira PD, Faustino AM. Feline plasma cell pododermatitis: A study of 8 cases. Vet Dermatol. 2003;14:333-337.
- Scott DW, Miller WH, Griffin CE. Miscellaneous skin diseases. In: Small Animal Dermatology.7th ed. Philadelphia, PA: WB Saunders Co; 2013: 718-719.