Low back pain as an initial symptom of pregnancy-associated breast cancer: a case report

Background Low back pain during pregnancy and postpartum is common and might not arouse clinical interest. Pregnancy-associated breast cancer is often found as a breast mass, but its diagnosis is difficult during pregnancy and postpartum. As more women delay their first pregnancies, its incidence may increase in the future. Case presentation The patient was a 30-year-old gravida 3, para 3. She had low back pain from the second trimester of her previous two pregnancies, which improved spontaneously after delivery. In her third pregnancy, she again developed low back pain in the second trimester. Her delivery was normal. However, her low back pain continued for up to 7 months postpartum and then worsened sharply. A whole-body scan revealed a compression fracture due to multiple spinal metastases of breast cancer. As she had not complained about her breasts, they had not been closely examined. Conclusions This case shows the importance of considering bone metastases from breast cancer in the differential diagnosis of patients with low back pain during pregnancy and postpartum.