Metastases and Primary Brain Tumors Affecting the Fornix of the Brain.

Background The aim of this study is to evaluate the clinical and radiological findings of metastatic tumors and primary brain tumors affecting the fornix. Methods  Between January 2015 and March 2023, we retrospectively evaluated 1087 patients of both sexes who underwent cranial magnetic resonance imaging (MRI) for a preliminary diagnosis of intracranial malignancy in the radiology department of our hospital. Two radiologists with six and 10 years of experience in MRI examination assessed the relationship between primary and metastatic tumors and the fornix. Results  Involvement of the fornix was diagnosed in 29 of the 1087 patients (2.66%), of which fornix was affected by metastatic lesions in 14 patients (48.2%) and primary tumors in 15 patients (51.7%). The majority of metastatic lesions were from lung and breast cancers, with other tumor types including osteosarcoma, renal cell carcinoma, pancreatic adenocarcinoma, pleomorphic sarcoma, and diffuse large B-cell lymphoma. Among all primary tumors, glioblastoma was the most common primary brain tumor invading the fornix, with other diagnoses including diffuse astrocytoma, medulloblastoma, and anaplastic oligodendroglioma. Metastatic and primary brain tumors affecting the fornix were detected over a broad timeline, from the time of diagnosis up to 120 months after diagnosis. A retrospective evaluation of medical records revealed memory deficits in four patients. Conclusion The fornix can be affected by both metastatic and primary brain tumors. It is crucial to understand the relevant neuroanatomical relationships when evaluating lesions that affect the fornix.