Solitary cerebral metastasis from undiagnosed prostate cancer. Potential role of multiparametric MRI prostate in pre-treatment diagnostic protocols

Abstract

A 73-year-old man presented with a three-week history of weakness and loss of co-ordination of the left-hand side and weakness of left-hand grip. MRI brain revealed an enhancing lesion in the right parietal lobe, adjacent to the central sulcus, with surrounding oedema and a small satellite lesion in motor cortex. Body CT and FDGPET CT revealed no obvious primary neoplasm. The patient underwent craniotomy with resection of the lesion, subsequent histopathology confirmed a metastatic carcinoma of likely prostate cancer primary origin. The patient was on 5-ARI (Finasteride) for lower urinary tract symptoms that decrease serum PSA levels to half and had benign feeling prostate on digital rectal examination (DRE). Subsequent MRI prostate confirmed presence of a lesion with very high probability of prostate cancer. The patient’s serum Prostate Specific Antigen (PSA) level was 6.8 (13.6 corrected for Finastride) which is relatively low in the context of metastatic disease. Given the recent NICE guidelines of using pre-biopsy multiparametric MRI (mpMRI) for diagnosis of prostate cancer, we suggest that in patients with cerebral metastases of unknown primary, with negative body CT, FDG PET-CT, low PSA and negative DRE, mpMRI prostate should be included in diagnostic protocol in the selected group of men, to enable early diagnosis and performing more suitable and targeted treatment.

Keywords: Brain metastasis; prostate cancer; multiparametric MRI; metastasis of unknown origin