Substantial Interobserver Variation Among Morphopathological Diagnosis Of Canine Mammary Gland Tumours From Veterinary And Human Pathologists

Abstract

Because the morphopathological diagnosis for the benignity or malignance of tumours has played a key role of therapeutic decisions and prognosis, the reproducibility and coherence among pathologists is important. To determine the level of interobserver variation for comparative studies among veterinary and human pathologists for the diagnosis of canine mammary gland tumours (MGTs), one hundred and thirty-six selected canine MGTs with histological slides were randomly divided into two groups: 68 cases were evaluated independently by three veterinary pathologists and one human pathologist; other 68 cases were reviewed blindly by one veterinary pathologists and three human pathologists. All the participating pathologists designated whether the canine MGTs are benign or malignant. Kappa (κ) statistics were calculated to evaluate the level of agreement. For three human pathologists involved in this study, moderate to good levels of agreement among their diagnosis (κ=0.68-0.81). However, three veterinary pathologists participated in this study show less than chance to slight levels agreement (κ= -0.06 to 0.25). In this study, human pathologists tend to diagnosed canine MGTs as benign lesions while veterinary pathologists tend to diagnose as malignant lesions. We conclude that substantially high interobserver variations do exist among pathologists and will greatly influence the research result and therefore; internationally accepted pathological diagnostic definitions with high accuracy and reproducibility among pathologists are required to assist global researchers in characterizing the tumour biology, natural history, and the comparison of treatment modalities of canine MGTs.