Occult Primary Breast Cancer Presenting with Ipsilateral Nodal Metastatic Disease

Occult primary breast cancer is a rare form of breast cancer that may present as axillary lymphadenopathy.When axillary lymphadenopathy is identified, further workup including biopsy and imaging should be done to rule out malignancy.Treatment for occult breast cancer typically involves axillary lymph node dissection and ipsilateral mastectomy, with a favorable prognosis.We present the case of a 66-year-old female with a past medical history of hemochromatosis who underwent magnetic resonance imaging of the abdomen to assess for iron deposition and was found to have right axillary lymphadenopathy.Breast imaging did not reveal a source for her lymphadenopathy but lymph node biopsy revealed metastatic carcinoma compatible with primary breast cancer.She was treated with multiple rounds of chemotherapy and received targeted axillary lymph node dissection to monitor treatment response.Pathology of the lymph node specimen from this biopsy revealed complete therapeutic response and no further evidence of malignancy.Our goal with this case report is to explore the recommended workup and treatment for occult primary breast cancer.