Brain metastasis of unknown primary: a diagnostic and therapeutic dilemma

The diagnosis of a brain metastasis is usually made during the routine follow up examinations of patients with known cancer, who are under the care of oncology departments. The involvement of the neurosurgeon depends on the philosophy and referral patterns of each oncology group. Patients with brain metastases of unknown primary (BMUP) are much more likely to seek the help of a neurosurgeon or a neurologist before contacting an oncologist, because the presenting clinical features originate from the brain. BMUPs are almost equal in numbers to brain primaries and differ from regular cerebral metastases regarding their site of origin, which will remain unknown in about 50% despite vigorous investigation. The clinical picture is similar to that of primary brain tumours but they seem to show different areas of predilection in the brain parenchyma. By reviewing the literature we are presenting the epidemiology, clinical presentation, diagnostic workup and treatment plan for this group of patients.