Development of neuro-Behcet's disease in a patient with operable HER2-positive breast cancer during neoadjuvant chemotherapy: A case report.

Background: Neuro-Behcet's disease (NBD) is a variant of Behcet's disease (BD). To our knowledge, there have been no previous reports on concurrent NBD in breast cancer patients undergoing chemotherapy.

Case presentation: Our patient had a history of BD and was asymptomatic. She was diagnosed with human epidermal growth factor receptor 2-positive breast cancer by core needle biopsy and was administered neoadjuvant chemotherapy. After four courses, in addition to the aggravation of the existing adverse events, headache, fever, dysarthria, and muscle weakness in the upper left and lower extremities appeared. On admission, she was diagnosed with acute NBD, and steroid therapy was initiated. After her symptoms improved gradually, she was discharged. Then, she underwent mastectomy and axillary lymph node dissection for breast cancer. Trastuzumab and pertuzumab plus tamoxifen were administered postoperatively. Two years postoperatively, no recurrence of breast cancer and NBD was noted.

Conclusion: When chemotherapy is administered to breast cancer patients with a history of BD, it is necessary to select chemotherapy with as few adverse events as possible and to continue with treatment while paying attention to the risk of NBD.