[en] Objective: To investigate histopathological and immuno phenotypic differences between breast carcinomas sporadic (CM E) and developed in the context of breast cancer (B C) Family (CM F). Methodology: The study included in the CME group (n = 34) patients (pts) with unilateral CM diagnosed after age 30 without family history of CM. In CM F group (n = 26) family members were included pts with 3 or more cases of CM (at least one diagnosed before age 50) or two cases with any of the following sub-criteria: at least one case diagnosed before age 35, paternal transmission, bilateral breast cancer, cancer ovary. Each group was subdivided into 2 subgroups according to age at diagnosis of CM: age equal to or greater than 40 years (subgroup 1) and age under 40 years (subgroup 2). It recorded the clinical characteristics and conventional anatomical and pathological parameters. By immunohistochemistry (IHC) expression of estrogen receptors was studied and progesterone (E R, P R), HER2, p3, bcl-2 and Ki67. Appropriate statistical tests were applied to Univariate and multivariate analyzes. Results: Mean age at diagnosis (45 vs 58, p <0.001) and tumor size (p <0.05) were lower in the CMF group than in the group with CME. In both groups predominant histological type was infiltrating ductal carcinoma NOS. He documented a tendency to higher histological grade and lower E R expression in CMF regarding CME. There were no differences in the expression of Pr, HER2, Ki67, bcl2 and p53. while in the CMF group no differences in tumor characteristics were observed by age diagnosis, in the CME, subgroup 2 showed a predominance of edges expansive growth, lower tubular differentiation, histological grade end stores III, minor component in situ, and low expression of RE. Discussion: Morphologic and immune phenotypic features are similar to the CMF studies documented in the United States and Europe, which agrees with the ancestral origin predominant in our population. Overall, the group presented a phenotype CMF tumor similar to that observed in tumors associated with BRCA2 mutations, or more ratio BRCA2 mutations and / or genes of unknown susceptibility. these results are in agreement with the prevalence of BRCA2 mutations in Uruguayan families recently reported by our group. Within the group with the CME under 40 pts years of diagnosis had a tumor phenotype similar to the tumor-associated BRCA1, so even in the absence of family history of CM, the investigation would be justified Germ line mutations in this gene. Conclusions: phenotypic characterization of breast carcinomas can contribute to selection of pts for conducting genetic tests in our population