A nasopharyngeal inflammatory polyp in a cat: histopathology, immunohistochemistry, and CT scan findings

Abstract

The etiology of feline nasopharyngeal inflammatory polyps (FNIPs) has not been completely understood. To the best of our knowledge, there is no study having evaluated the immunohistochemical features of FNIPs. More studies about the histopathological characteristics of such lesions can play a pivotal role in further understanding the disease. We present the clinical manifestations, computed tomography (CT) scan, histopathology, and immunohistochemistry features of a FNIP in a 7-year-old male neutered domestic shorthair cat. CT scan examination showed nasopharyngeal space occupation with some parts of destruction in nasal cavity. Immunohistochemical study of the sections demonstrated the presence of CD3$^{+}$ lymphocytes, and no reactivity was seen with CD79a. Masson's trichrome staining of the sections showed focal deposition of collagen fibers, and no goblet cells were observed in PAS staining. In conclusion, the significant neutrophilic and lymphocytic infiltration along with tissue edema and increased fibrin and collagen deposition probably point to the involvement of both innate and probably adaptive immune systems in FNIPs. Furthermore, in histopathological studies, there were no remarkable findings of allergic reactions.