An osteogenesis imperfecta case with breast cancer.

Osteogenesis imperfecta (OI) is a rare connective tissue disease characterized by abnormalities of type 1 collagen and an increased risk of bone fractures. Several OI cases with malignancies have been reported. Herein, we describe an OI case with breast cancer. A 36-year-old premenopausal woman with OI was admitted to our hospital for evaluation of a right breast lump. We diagnosed right breast cancer with axillary and parasternal lymph node metastasis (T2N3M0 stage IIIC). The tumor had increased in size and tumor markers were elevated after 10 months of hormone therapy. We performed a right mastectomy and axillary dissection. She subsequently received adjuvant chemotherapy and radiotherapy. She is currently taking trastuzumab and tamoxifen. Anesthesia is challenging in OI patients because of difficulty with airway control and intubation. We performed the mastectomy in this case without difficulty by working in cooperation with experienced anesthesiologists, orthopedists, and other medical personnel. Some OI patients reportedly have severe 5-fluorouracil (5-FU) toxicity related to dihydropyrimidine dehydrogenase (DPD) deficiency. DPD is the main enzyme involved in the catabolism of 5-FU. Our present case also had low DPD activity and we thus chose epirubicin and cyclophosphamide for chemotherapy. Our search of the literature yielded only two OI cases with breast cancer as of April 2011. To our knowledge, this is the first case reported in Japan.