Intraventricular metastases are a rare occurrence, particularly from a primary colorectal malignancy. To our knowledge, this is the first report of intraventricular metastasis from rectal cancer. A 72-year-old male presented with a new diagnosis of multiple intraventricular lesions, an anterior mediastinal mass and a rectal mass. His workup revealed rectal adenocarcinoma with intraventricular metastases and an incidental thymoma. Ommaya reservoir placement was performed via an awake procedure rather than under general anesthesia due to airway concerns. Cerebrospinal fluid (CSF) cytology was positive for malignancy and consistent with adenocarcinoma. Two weeks postoperatively, the patient underwent whole brain radiation. Although rare, this diagnosis should always be considered in the differential for solitary or multiple intraventricular lesions. CSF sampling is a useful alternative to intraventricular biopsy for diagnosis of intraventricular metastases. Awake placement of Ommaya reservoir is a safe option in the management of patients with intraventricular metastases, especially those who cannot undergo general anesthesia.
Keywords: Ommaya reservoir; cerebral metastasis; cerebrospinal fluid sampling; colorectal cancer; intraventricular tumors.