Plasmocitoma extramedular de terceira pálpebra em gato / Extramedullary plasmacytoma of the third eyelid in a cat

ABSTRACT

Background: Extramedullary plasmacytoma is a neoplasm originating from plasmacytes with benign behavior, althoughit can present malignant characteristics such as local invasion and metastases in some cases. Primary extramedullary plasmacytoma in the third eyelid is rare in humans and animals and has not yet been described in cats. Thus, the goal of thepresent study is to describe the cytological and histopathological findings of an extramedullary plasmacytoma in a cat’sthird eyelid.Case A 5-year-old female feline patient with a history of ocular alteration for approximately 30 days was referred tothe ophthalmology service. Upon ophthalmic examination of the left eye, an increase in volume with tissue proliferationwas identified in the third eyelid’s conjunctiva. A collection of material for cytopathological examination was performed.Numerous plasmocytes and atypical lymphocytes with anisocytosis and anisokaryosis were observed, with a possible neoplastic injury being suggested and referred to the patient for surgical removal of the third eyelid. In the histopathologicalanalysis, it was possible to observe several plasma cells and vascular neoformation along the entire conjunctive marginbelow the epithelium. The glands, serous and mucous, present in the fragment, revealed areas of intervening plasmacyticinfiltrate and a large area close to the hyaline cartilage containing intense plasmacytic inflammatory infiltrate with rareneutrophils and macrophages. There was also a structural breakdown of glandular components and lymphocyte cells withmitosis figures and discrete cellular pleomorphism.Discussion: Plasmacytoma is a rare neoplasm in both dogs and cats. The anatomical regions most frequently affected arethe digits, lips, and pinna. Concerning the 3rd eyelid tumor involvement, numerous...