Occult breast cancer presenting as axillary metastases

We report the case of a 52-year-old woman with occult breast cancer who presented with a hard metastatic nodule in the left axilla. Although histology identified a metastatic adenocarcinoma in the lymph nodes, numerous tests failed to detect the primary tumor. Immunohistochemistry showed that the resected lymph node was positive for both estrogen and progesterone receptors, suggesting the breast as the site of the primary tumor. Left modified radical mastectomy was performed. Pathology revealed an invasive ductal carcinoma (1.5x1 mm in size) with extensive lymphatic involvement, which strongly expressed both vascular endothelial growth factor-C (VEGF-C) and VEGF-D.