IMMUNOHISTOCHEMICAL DISTRIBUTION PATTERN OF INTERMEDIATE FILAMENT PROTEINS IN 50 FELINE NEOPLASMS

Twenty-eight epithelial and 22 nonepithelial feline tumors were studie d immunohistochemically. Epithelial tumors were 10 squamous cell carci nomas, two basal cell tumors, two sebaceous gland carcinomas, three ap ocrine gland carcinomas, three thyroid papillary carcinomas, one thyro id solid carcinoma, one renal clear cell carcinoma, one renal papillar y carcinoma, one endometrial carcinoma, and four lung bronchioloalveol ar carcinomas. Nonepithelial tumors were 10 fibrosarcomas, one liposar coma, one leiomyosarcoma, one rhabdomyosarcoma, one hemangiosarcoma, t wo mast cell tumors, one osteosarcoma, three melanomas, and two lympho mas. Commercially available antibodies directed against high- and low- molecular-weight keratins (keratin, RCK-102, NCL-5D3), vimentin, desmi n, glial fibrillary acidic protein (GFAP), and neurofilament intermedi ate filament (IF) proteins were used in the avidin-biotin-peroxidase c omplex technique on formalin-fixed, paraffin-embedded tumor tissue sam ples. All epithelial tumors except the endometrial carcinoma expressed some type of keratin protein. Squamous cell carcinomas expressed high -molecular-weight keratins exclusively. Coexpression of high- and low- molecular-weight keratins was observed in one basal cell tumor, sebace ous and apocrine adenocarcinomas, and thyroid, renal, and lung carcino mas. In addition to keratins, vimentin immunoreactivity was found in a ll basal cell tumors, all sebaceous gland, thyroid papillary, renal, a nd lung adenocarcinomas, and one of the apocrine gland adenocarcinomas . Immunoreactivity with GFAP antibody was found in one basal cell tumo r and one sebaceous gland adenocarcinoma. The endometrial carcinoma di d not react with any of the antibodies applied. Nonepithelial tumors a nalyzed expressed either vimentin (fibrosarcomas, liposarcoma, haemang iosarcoma, mast cell tumors, osteosarcomas, melanomas) or vimentin and desmin (leiomyosarcoma, rhabdomyosarcoma, one fibrosarcoma) IF protei ns exclusively. Lymphomas did not react with any of the antibodies emp loyed. These findings indicate that IF proteins antibodies can be incl uded in diagnostic panels of antibodies for immunocharacterization of feline tumors. In addition, they can be used as a basis for the diagno ses of poorly differentiated or undifferentiated feline neoplasms.