Comparison of effusion cell block and biopsy immunohistochemistry in mesothelial hyperplasia, mesothelioma, and carcinoma in dogs

• Published in: Veterinary clinical pathology 2021-12, Vol.50 (4), p.555-567
• Main Authors: Milne, Elspeth M., Piviani, Martina, Hodgkiss‐Geere, Hannah M., Piccinelli, Chiara, Cheeseman, Michael, Cazzini, Paola, Ressel, Lorenzo, Marcos, Ricardo J., Marrinhas, Carla S., Santos, Marta S., Thomas, Emily K., Drummond, Dawn, Martinez Pereira, Yolanda
• Format: Article
• Language: English
• Subjects: Animals; Biomarkers, Tumor - analysis; Biopsy; Biopsy - veterinary; Cancer; canine; carcinoma; Carcinoma - veterinary; cell block; Diagnosis, Differential; Dog Diseases - diagnosis; Dogs; Hyperplasia; Hyperplasia - veterinary; Immunohistochemistry; IMP3; Mesothelioma; Mesothelioma - diagnosis; Mesothelioma - veterinary; WT1
• ISSN: 0275-6382; 1939-165X
• DOI: 10.1111/vcp.13002

Background Determining the cause of effusions is challenging and might require a biopsy. Whether cell blocks from effusions are representative of biopsies requires investigation. A previously developed immunohistochemical panel aids in the differentiation of hyperplastic and neoplastic mesothelium in canine biopsies but has not been investigated in effusions. Objectives The study aimed to assess cell blocks as an alternative to biopsies and determine whether immunohistochemistry helps distinguish hyperplastic mesothelium, mesothelioma, and carcinoma. Methods Effusions and biopsies were collected from five dogs with mesothelial hyperplasia (group MH), six with mesothelioma (group M), and five with carcinoma (group C). Immunohistochemistry (IHC) for cytokeratin, vimentin, Wilm's tumor protein 1 (WT1), desmin, glucose transporter 1 (GLUT1), and insulin‐like growth factor II mRNA‐binding protein 3 (IMP3) was performed. Sections were scored for staining intensity and the percentage of positively stained cells. Results In paired cell blocks and biopsies, vimentin and WT1 staining were positively correlated for intensity and the percentage of positive cells, although not all paired results were identical. The intensity of IMP3 staining in cell blocks was higher in group M than in group C (P = 0.012), and WT1 staining was higher in group MH than in group C (P = 0.020). For biopsies, the intensity of WT1 staining was higher in group MH than in group C (P = 0.031). In group C, WT1 was negative in all cell blocks and biopsies, and desmin was negative in four of five cases. Conclusions IHC results for the cell blocks and biopsies were comparable for potentially useful markers, such as WT1, which helped discriminate between groups. IHC provided additional information, although results were not always definitive. Further studies on a larger population are required.