Plasma cell pododermatitis and mast cell tumor in a cat

A four-year-old neutered male Domestic Shorthair cat was presented for an inflamed mass into left central metatarsal footpad. The mass was noticed 3 months after the surgical treatment to the femoral fracture by closed reduction, with a rod insertion into the bone by retrograde way, associated with a plate fixed by screws to a frame. Dermatological examination showed soft, spongy swelling footpad and regional lymphadenopathy. Routine hematology and blood chemistry values were in the physiological range. The cat was FIV/FeLV negative. Treatment was started with steroids (prednisolone 4 mg/kg q 24 h for 7 days) and doxycycline (10 mg/kg q 24 h for 4 weeks) administered orally. It wasn’t noticed any improvement so the mass was surgically removed. Histological examination revealed an intense inflammatory infiltrate composed of mature plasma cells, in a predominantly perivascular pattern and interspersed trough the hyperplasic derma. Interestingly, the central area of the removed tissue showed an heavy infiltration of well differentiated mast-cells associated to scanty eosinophils. Plasma cell pododermatitis, a rare feline disorder, recognizes immune-mediated mechanisms and a inflammatory condition that lasts over time. The skin chronic inflammation may play a role in the development of cutaneous mast cell tumors (MCT), but only in dog and in rare cases have been documented MCT associated with chronic dermatitis, scar formation or application of skin irritants (Welle e coll., 2008). There are, to the author's knowledge, no previous descriptions of a plasma cell pododermatitis associated to a mast-cells tumor in the same footpad, appeared after an orthopedic surgery in the cat.