Introduction: There is consistent information that suggests the presence of unfavorable clinicopathological characteristics in patients with breast cancer associated with pregnancy that report frequent involvement of nodes, locally advanced disease, less presence of hormone-sensitive tumors and higher incidence of metastatic disease. Case report: A 26 year-old female that, immediately after delivery, developed arm pain associated with functional limitation during the breastfeeding of her son in 2010. After humerous pathological fracture was found, workup started and showed a left breast tumor (5 × 4 cm in largest diameter), without skin involvement, and clinically negative axillary nodes. Biopsy of the breast mass revealed an invasive ductal carcinoma, moderately differentiated, ER and PR positive, and HER2 negative. Bone scan showed bone metastases. The patient was treated with chemotherapy based on 5-fluorouracil/doxorubicin/cyclophosphamide followed by weekly paclitaxel. Partial response was achieved and she continued with tamoxifen, palliative radiotherapy at humerous and monthly zoledronic acid. In July 2014, she presented with back pain and limitation of her daily activities; workup demonstrated disease progression to pelvis and vertebrae. Exemestane and everolimus was started, achieving total pain relief within two weeks. After three months of treatment, partial response was shown in CAT scan. Conclusions: Pregnancy associated breast cancer women have poor outcomes, characterized by the presence of unfavorable clinicopathological characteristics, delay and difficulties in diagnosis, and physiological changes involving pregnancy that affects hormonal status and mammary tissue. In the clinical case that we present, even when she was diagnosed with metastatic disease, after four years of follow-up she has had a good evolution.