RESUMO
To propose a diagnostic work-up specifically tailored to the undiagnosed primary [UDP] tumor patients. To investigate the distribution of primary tumors and presenting symptoms in UDP versus diagnosed primary [DP] patients, 50 consecutive patients with diagnosis of brain metastasis in Shohada Hospital, Tehran, Iran from January 2001 to December 2005 were included in this study. Univariate analyses were performed to assess the difference of various variables between DP and UDP patients. The UDP patients represented 46% of all. Aphasia was significantly more common in the UDP group [p=0.0008] and ataxia in the DP group [p=0.04]. The source of the metastases proved to be different between the 2 groups of interest [p=0.0006]. The lung was the most frequent primary site in both groups. Among all UDP patients, a primary tumor in a location other than the lung was only found in 17% of patients. This study validated the hypothesis that the distribution of primary tumors differs between DP and UDP patients. If lung investigation fails to disclose the location of primary tumor, the patient is unlikely to benefit from extensive paraclinical investigation. In such a situation, a neurosurgical procedure should be considered the most appropriate second step to be taken