Axillary schwannoma mimicking lymph node metastasis-associated breast cancer: a case report

Background Axillary schwannoma associated with breast cancer is an extremely rare disease, and previous reports have been limited. In this setting, there is great concern about whether a tumor in the axillary region is lymph node metastasis. Herein, we report a unique case of axillary schwannoma that mimicked lymph node metastasis associated with breast cancer. Case presentation A 68-year-old woman who underwent mastectomy and axillary lymph node dissection for right breast cancer over 20 years ago presented to our hospital with numbness and weakness in the right arm for 6 months. Ultrasonography, computed tomography, and magnetic resonance imaging showed a 20-mm well-circumscribed round tumor in the right axillary region. Initially, she was suspected of having lymph node metastasis-associated breast cancer, but the result of the core needle biopsy was a schwannoma. The patient underwent tumor enucleation. The patient has had no recurrence 1 year after the operation. Conclusion Axillary schwannomas often mimic lymph node metastasis in patients with a history of malignancy, particularly breast cancer. To select the optimal treatment, the clinicians should make as accurately as possible a diagnosis, with histopathological examinations, when examining patients with cancer who develop tumors in the axillary region.