Multiple Lymph Node and Bone Metastases From An Occult Breast Cancer: A Case Report

Cancer of unknown primary is defined as cancer with an unknown primary origin. Occult breast cancer (OBC) is a rare diagnosis in which physical examination, imaging methods, and even surgical procedures are insufficient to put on a primary tumoral site in the breasts. This definition leads to only 0.3-1% of all breast cancer cases. The diagnosis of OBC is usually obtained with an axillary lymph node biopsy. A 52-year-old female presented with right arm weakness and a neck lump. On the physical examination, multiple masses were palpated at the right axillary, right supraclavicular, and anterior cervical areas. Mammography, breast ultrasonography, breast magnetic resonance imaging, and 18-fluorodeoxyglucose positron emission tomography (18-FDG PET) scan could not show a suspicious tumoral area as the primary origin. 18-FDG PET scan put on the massive tumoral burden at multiple bones and lymph nodes, but there were no lesions to suspect as the tumoral origin. Finally, the supraclavicular lymph node biopsy result has revealed the diagnosis; hormone receptor-positive and C-erbB2 positive occult breast cancer. Cervical lymph node metastasis is also a scarce condition for breast cancer. The lymphatic drainage pathway is not clear in explaining the breast cancer involvement of the cervical.