The term breast cancer in pregnant women is used when the disease has been diagnosed during pregnancy or within first 12 months after delivery. The frequency of this type of breast cancer is about 7% of all cases in reproductive period. We present a case of breast cancer that occurred in pregnant 35 year old woman. We performed histological and immunohistochemical tests of excised tumor formation. We did not find sufficient evidence of both carcinoma in situ and invasive ductal carcinoma. The lesion was consisted with encapsulated/intracystic carcinoma, solid papillary variant with a low degree of differentiation-G3. Young age of patient, receptor status of the tumor the characteristic morphology of hereditary cancer, the presence of inflammatory infiltrates intratumorally, absence of reaction to IHC protein product of the tumor suppressor gene BRCA1 in combination with a positive p53 IHC makes this case suitable for genetic testing of BRCA1/BRCA2 susceptibility genes. The case is interesting because of the rarity of the histological variant, the young age of the patient, the combination with BC and pregnancy and the triple-negative phenotype.