Flow cytometric DNA ploidy analysis of feline mammary tumors.

Flow cytometric DNA analysis was performed on biopsies from 9 nonmalignant and 111 malignant (primary and metastatic) feline mammary lesions. In our series, 46.3% of the primary mammary carcinomas appeared to be aneuploid, whereas all but one benign breast lesion were diploid. The degree of aneuploidy in carcinomas was low, with a relatively high number of primary tumors (12 of 82) displaying hypodiploidy. Aneuploidy was not found to be correlated with any specific histological tumor type, vascular invasion, tumor size, or histological malignancy grade or with the separate components thereof. Comparison of the ploidy in primary and metastatic tumors from the same cases revealed a remarkable stability, both in time and location of appearance of the metastases. It is concluded that with respect to DNA ploidy feline mammary carcinoma has more in common with canine mammary carcinoma than with human mammary carcinoma. Further prospective studies are necessary to clarify the implications of aneuploidy in feline mammary carcinoma for tumor behavior and prognosis.

The accuracy of cytology in diagnosis and DNA analysis of canine mammary tumours.

Fine-needle aspirates from 84 spontaneous canine mammary tumours were used to assess the accuracy of this method in flow cytometric DNA analysis and cytological diagnosis. Defined samples from different tumour parts were analysed for histological diagnosis and DNA ploidy as a control. The DNA ploidy in cytology specimens and those obtained from the defined tumour samples, when testing for independence, was highly significant (P = 0.0001). The total accuracy of cytology was 79 per cent, with a sensitivity of 65 per cent and a specificity of 94 per cent. The results show the possibility of combining cytology and DNA analysis of fine-needle aspirates from canine mammary tumours. The method is suitable for preoperative diagnosis of canine mammary tumours as well as for measuring DNA ploidy, which makes it useful if DNA ploidy turns out to be of diagnostic and prognostic value in these tumours.

The expression of intermediate filaments in canine mammary glands and their tumors.

Monoclonal antibodies specific for different types of intermediate filaments (cytokeratin, vimentin, desmin and neurofilaments) were used to study the histogenesis of canine mammary glands and 57 canine mammary tumors by immunocytochemistry. The intra- and interlobular duct epithelium, acinar, and intralobular myoepithelial cells stained positively for cytokeratin. Peripheral ductal and acinar cells, as well as interstitial cells, stained positively for vimentin. A similar staining pattern was seen in adenomas, complex adenomas, benign mixed tumors, ductular carcinomas, and one myoepithelioma-like tumor. Additionally, cytokeratin positive cells were scattered interstitially in one single adenoma, most complex adenomas, some benign mixed tumors, complex carcinomas, and in the malignant mixed tumors. All stromal cells stained positively for vimentin. The fibrosarcomas were positive only for vimentin, while the following expressed both desmin and cytokeratin: epithelial-like cells in one adenoma, three complex adenomas, the myoepithelioma-like tumor, the single comedo carcinoma, two complex carcinomas, the single lobular carcinoma, one malignant mixed tumor, and three osteosarcomas. Epithelial-like cells in one adenoma, six complex adenomas, two benign mixed tumors, two complex carcinomas, the lobular carcinoma, and the malignant schwannoma stained for neurofilaments. Three tumors, one adenoma, one complex adenoma, and the lobular carcinoma expressed both desmin and neurofilaments in addition to cytokeratin and vimentin. The results show the expression of different types of intermediate filaments and indicate that there might be a stem cell origin in most of the canine mammary tumors.