We reported a case of miliary brain metastases and reviewed the literature to discuss the definition and the clinical implications.

Miliary brain metastases also called carcinomatous encephalitis, is a rare identity that has been described in several case reports over the past fifty years. The definition is radiologic-pathologic and has been applied to similar clinical presentations but with variable imaging findings. 

After presenting the case of our patient, we reviewed the case reports found in the literature since the mid twentieth century using 'miliary brain metastases' or 'carcinomatous encephalitis' keywords and analyzed the clinical, radiological and pathological findings of the patients.

A 70 year-old man presented with four weeks of confusion, memory impairment, diplopia, shuffling gait and was found with numerous small cerebral supra and infra-tentorial enhancing small lesions, prompting to the discovery of non small cell lung carcinoma. His cognitive functions deteriorated rapidly, limiting the therapeutic options to whole brain radiation therapy and leading to death within three months. The previously depicted cases showed similar clinical presentations with rapid debilitating course including change in mental status, cognitive impairment, seizures or motor deficits and were associated with poor prognosis. Imaging showed multiple small lesions throughout the parenchyma and brainstem. However, some authors pointed out a lack of enhancement and even the absence of lesions on imaging. Pathological studies confirmed the tumoral spread in the central nervous system (CNS) through peri-vascular and sub-pial spaces in most cases.

Miliary brain metastases could be defined by radiological findings of multiple small enhancing or non enhancing lesions of the CNS and should be confirmed by pathology. It is a differential diagnosis of rapidly progressive dementia that should prompt a cancer work-up and its associated poor prognosis should weight in the decision of cancer treatment.