Canine mammary tumour: Histopathological evaluation at different depths of tumour mass

The present study reports the histopathological evaluation of a well matured long standing case of a massive mammary tumour at different depths of tumour mass in a nine years old non-descript bitch. The massive tumour occupying the posterior pairs of mammary gland weighing around 5.2 kgs was dissected into three circular layers (outer, middle and inner) of two inches in thickness in order to study the histopathology at different depths of tumour mass. Each layer was cut into different pieces and subjected to histopathological evaluation. The outer layer revealed only benign tumours (fibroma and adenoma), middle layer showed mixed benign tumours (fibroadenoma and chondro-adenoma) and the inner layer comprised of only malignant tumours (papillary adenocarcinoma and chondrosarcoma). Transformation of myoepithelium into chondrocytes resulting in chondroma could be observed in the middle layer. It is concluded that in well matured mammary tumour, degree of malignancy increases from the outer area to the centre of the tumour.