Metastatic breast cancer can have protean manifestations. Here we present a case of a woman with recurrent breast cancer who presented with acute dyspnea and evidence of right heart strain. Diagnoses of myocardial ischemia and of pulmonary embolus were ruled out and the patient ultimately succumbed to respiratory failure. At pathology she was found to have tumor emboli clogging capillaries and arterioles, consistent with the diagnosis of embolic carcinomatosis. While a rare diagnosis, clinicians must be aware of this phenomenon in patients with breast cancer who present with rapidly deteriorating pulmonary function.