Moo, a neutered 6-year-old domestic shorthair male cat (Figure 1), presented to Boca Midtowne Animal Hospital for a second opinion on two large, erythematous, infected dermal masses attached to the plantar aspect of two separate digital pads of his left pelvic limb (Figures 2-A, 2-B). The previous veterinarian had recommended amputation of the digits due to the rapid growth of these masses and concern for inadequate surgical margins.
Histopathology of the masses confirmed the diagnosis of plasma cell pododermatitis, chronic active, diffuse and severe with ulceration and granulation tissue (Figure 3). This disease is seen uncommonly in cats and rarely in dogs. Lesions may be confined to a single pad or may involve multiple pads or feet. In some cases, increased vascular fragility may result in secondary hemorrhage. Chronic involvement of a single pad may respond best to surgical removal. The cause of plasmacytic pododermatitis is not known; presumably the lesions result from persistent antigenic stimulation, as seen in chronic plasmacytic inflammation of mucous membranes. A few cats have coexistent plasma cell stomatitis, immune-mediated glomerulonephritis or renal amyloidosis.