We report a rare clinical presentation of breast carcinoma metastasis to the ethmoid sinuses, orbit and cavernous sinus in a 70-year-old lady with unsuspected breast carcinoma who presented with clinical features of acute ethmoiditis, orbital cellulitis and cavernous sinus thrombosis. The patient underwent endoscopic ethmoidectomy and histology of the necrotic tissue from the ethmoidal cells was positive for endovascular neoplastic emboli. Subsequent examination revealed a large mass in the left breast, tethered to the skin, which was histologically confirmed to be a carcinoma. The patient died 2 months post-diagnosis. To our knowledge, this is the third case manifesting with combined features of ethmoiditis, orbital cellulitis and cavernous sinus syndrome from an unsuspected breast carcinoma. This case highlights the importance of imaging and thorough physical examination when a dramatic clinical picture presents in the paranasal sinuses of an otherwise healthy individual. Such manifestation of breast carcinoma is difficult to diagnose, and therefore, a high index of suspicion should be maintained. Skull base metastases from breast carcinoma behave aggressively and if diagnosed early, treatment may prolong survival and improve quality of life.