Nasopharyngeal Carcinoma With Bilateral Breast Metastasis: A Report of an Elusive Case.

Nasopharyngeal carcinoma is a prevalent head and neck cancer, especially in Southeast Asia. Although its potential for distant metastasis is well established, metastasis to the breast has seldom been reported. To the best of our knowledge, this is the fourth report of a case of nasopharyngeal carcinoma metastasizing to bilateral breasts. A 35-year-old patient presented with left nasal obstruction, epistaxis, and a palpable mass in her left breast, without any cervical or axillary lymph nodal enlargement. Radiological examination with contrast-enhanced computed tomography scan and magnetic resonance and imaging of breast revealed the presence of enhancing mass lesions in bilateral breasts. Histopathology of the nasal mass was suggestive of undifferentiated nasopharyngeal carcinoma. Breast fine needle aspiration revealed an abundance of metastatic squamous cells. Immunohistochemistry examination was positive for chromogranin A, synaptophysin, and cluster of differentiation-56, confirming the diagnosis of a primary nasopharyngeal malignancy metastasizing to bilateral breasts. Differentiation between metastatic disease and a coexisting second primary is imperative for planning appropriate treatment and defining the further outcomes.