A 67 year old male presented to our service with right jaw pain and facial numbness. He had a past medical history that included prostatic adenocarcinoma with known bony metastases throughout his appendicular skeleton as well as to his sacrum, multiple ribs, sphenoid bone and frontoparietal region of the skull with relative sparing of the spine. He declined systemic chemotherapy at the time of diagnosis and traveled back to his home country of Jamaica, therefore was being treated only with leuprolide and denosumab, which he had stopped two months prior to presentation.
Clinical examination was notable for right facial numbness with rightward deviation of the tongue. CT scan demonstrated an acute on chronic left sided subdural hematoma with thickening of the overlying dura mater as well as a small right frontal chronic subdural hematoma. MRI demonstrated nodular dural thickening overlying the hematoma as well as leptomeningeal enhancement within the left cerebral hemisphere (image 1). Lumbar puncture demonstrated a mildly elevated protein but no malignant cells on cytology. Leptomeningeal biopsy confirmed the diagnosis of metastatic prostatic adenocarcinoma. The patient opted for palliative whole brain radiation and a short course of dexamethasone with improvement in facial numbness.
Discussion:
Prostate cancer is the most commonly diagnosed cancer among men in the USA, with over 100 000 new diagnoses forecast in 2016. The most common sites of metastasis are to the bones, lungs and liver.
Though spread to the meninges is rare, prostate cancer is the most common primary malignancy identified in leptomeningeal carcinomatosis. Leptomeningeal prostate cancer is being reported with increasing frequency, likely due to improved imaging techniques as well as better treatment options for advanced disease leading to improved survival.
Clinical presentation of leptomeningeal carcinomatosis is variable and patients most commonly present with symptoms of increased intracranial pressure (23.5%), neurological deficits (20%), or seizures (9%). Subdural hematoma is seen in up to 41% of dural metastases of any primary malignancy and have been well described in metastatic prostate cancer.
Cytological diagnosis is hampered by high false negative rates of CSF cytology, although repeated sampling increases sensitivity. Case reports have used CSF PSA levels to support the diagnosis in such cases and new modalities such as rare cell capture technology show promise. Neuroimaging is also hampered by limited sensitivity, with MRI considered to be superior to CT. Some suggest that in the presence of advanced disease, characteristic MRI findings and multiple neurological deficits, therapy should be started even with normal CSF cytology.
Conclusions:
While leptomeningeal metastasis of prostate cancer remains a rare event, clinicians must maintain a high level of suspicion for patients with known metastatic disease who present with subdural hemorrhage. Current diagnostic methods including neuroimaging and CSF cytology are limited by low sensitivity, but CSF PSA levels represent a promising biomarker to support the diagnosis in a patient with characteristic imaging findings and known metastatic prostate cancer, potentially avoiding the need for more invasive diagnostic procedures such as dural biopsy.