Histochemical study of fibrillar proteins of the extracellular matrix in benign and malignant mammary neoplasms in dogs

The aim of the present study was to study some of the proteins that form the extracellular matrix of 54 benign and malignant mammary neoplasms in dogs, using histochemical methods: Picrosirius and polarization microscopy for collagenous fibers, Gordon -Sweats's method for reticular fibers and Weigert's fucsine-resorcine method for elastic fibers. A large variability in quantity, distribution and characteristics of the matrix components was observed in the different types of neoplasms. Collagen type I, III and elements of the elastic system had different distribution in benign and malignant neoplasms. The simple Picrossirius method and under polarization enabled visualization of collagen as thick fibers irregularly distributed in the stroma of carcinomas and in a more orderly and regular fashion in benign neoplasms. A smaller amount of thin fibers was observed in an irregular and random disposition in carcinomas and in a regular disposition in benign neoplasms . Under polarization, the fibers present different lengths, were yellowish or reddish and strongly birefringent, what suggested that they were collagen type I and in the middle of these fibers, other ones, pale, greenish and weakly birefringent, some of them thinner, possibly collagen type III were observed. In the stroma of carcinoma, fibers were mostly thick, strongly birefringent, yellowish or reddish, disposed in an irregular and random fashion, mainly in the central areas. In condrometaplasic areas, both in malignant and benign neoplasms, there was a collagen population composed by thin fibers in a parallel disposition, limiting narrow regions where condrocytes were aligned. Around this area, there was a collagen population formed by bundles of thick anastomosed fibers, irregularly disposed in carcinomas and orderly, in a parallel fashion in benign neoplasms. Under polarization demonstrated that this population, among condrocytes, was formed by weakly birefringent fibers, pale and yellowish, what suggested a collagen type II pattern. The use of reticular fibers staining by Gordon & Sweats, enabled a visualization of collagen as thin fibers disposed not only in the dense stromas but also in the loose ones. These fibers presented variable density, but were found mainly around acini and tubules. In relation to the presence elements of the elastic system in benign and malignant tumors, it may be observed that they predominate in the malignant ones, mainly in the pseudocapsule and around acini...

Retrospective review and systematic study of mammary tumors in dogs and characteristics of the extracellular matrix

The aim of the present study was to perform a retrospective review, from 1932 to 1999, in order to establish the number of cases of mammary tumors in dogs in the records at the Pathology Department of Faculdade de Medicina Veterinária - USP, as well as the presence of desmoplasia and cartilaginous and bone metaplasia in 578 of these tumors. Among the 537 malignant tumors, 13.05 percent were simple tubular adenocarcinomas, 3.91 percent were complex tubular adenocarcinomas, 7.26 percent simple papillary adenocarcinomas, 4.28 percent complex papillary adenocarcinomas , 23.27 percent simple papillary cystadenocarcinomas ,8.37 percent complex papillary cystadenocarcinomas,16.38 percent simple solid adenocarcinomas ,6.70 percent complex solid adenocarcinomas, 2.04 percent simple spindle cell carcinomas, 1.11 percent simple spindle cell carcinomas ,2.79 percent mucinous carcinomas ,8.19 percent anaplastic carcinomas ,0.93 percent squamous carcinomas, 1.30 percent fibrosarcomas,.0.18 percent chondrosarcoma, 0.18 percent osteosarcoma and among the 41 benign tumors ,51.21 percent were adenoma, 12.19 percent papillary cystadenoma,7.31 percent papilloma, 4.87 percent cystic fibroadenoma and 24.39 percent were fibroadenoma. Both desmoplasia and metaplasia were frequent findings in benign and malignant neoplasms, but they were more frequent among complex tubular adenocarcinomas: 38 percent presented desmoplasia, 57 percent cartilaginous metaplasia and 28 percent bone metaplasia. Among the benign neoplasms, adenoma presented the more frequency: 14 percent presented desmoplasia, 29 percent cartilaginous metaplasia and 24 percent bone metaplasia. Results of this study emphasize the complexity of the inter-relationship between the macromolecules in the extracellular matrix and tumoral cells