Feline progressive histiocytosis in four cats: case reports

We describe four cases of feline progressive histiocytosis (FPH) including three females (one intact, two spayed) and one castrated male cat, with a mean age of 5.95 years at diagnosis. Masses were found under the skin of head, lip, neck, and vulva. Histologically, proliferative round cells had ovoid nuclei, foamy eosinophilic cytoplasm, distinct cytoplasmic processes, and mitotic figures. Immunohistochemically, all cases were positive for Iba1 and MHC II (Dako). One case showed cytoplasmic positive staining for E-cadherin. To the best of our knowledge, this is the first documented report of FPH in Korea.