Multiple Intracranial Fibrous Tumors with Multi-Modal and Functional MR Imaging
Intracranial solitary fibrous tumors (ISFTs) are rare neoplasms derived from the mesenchyme. As the name suggests, ISFTs are solitary lesions on initial presentation, and can be found within the supratentorial as well as infratentioral fossae. To our knowledge, ‘multiple’ ISFTs have always been reported in the postoperative population and are thought to be secondary to surgical cerebrospinal fluid (CSF) dissemination. We report the first known case of multiple intracranial ‘solitary’ fibrous tumors in a patient without history of prior surgery. A 52-year-old African American male presented with progressive weakness, pain, and numbness in all extremities, with ataxia, bowel and bladder incontinence, and a 30 pound weight loss in two months. The patient denied headaches, dizziness, blurry vision, double vision. Physical exam revealed weakness in all extremities, decreased sensation to light touch in upper extremities bilaterally, intact reflexes, ataxia, dysmetria, and an intact rectal tone. Past medical history was unremarkable for remote head or spine surgery, chemotherapy, or radiation. Routine serological chemistry was non-contributory. Initial imaging workup included a noncontrast head CT. Upon discovery of a posterior fossa mass lesion, a contrast enhanced MR was performed and additional imaging work-up with catheter angiography, functional MR spectroscopy, and MR perfusion imaging was performed, thereafter. Ultimately, a suboccipital craniotomy was performed for gross total resection. Surgical and histopathology review yielded a diagnosis of Intracranial Solitary Fibrous Tumors (ISFTs) of the dura. There were no signs of recurrence on the one year follow-up contrast enhanced MR examination. On noncontrast head CT imaging, an isoattenuating to slightly hyperattenuating midline posterior fossa mass was identified (Figure 1E). Contrast-enhanced MR imaging revealed two separate T1-isointense, T2-hypointense masses and avid homogeneous enhancement on post-gadolinium administration. The larger mass was epi-centered in the fourth ventricle while the second smaller mass was dural based within the inferior right posterior fossa (Figure 1C). The larger mass demonstrated compression of the adjacent cerebellum and medulla (Figure 1). Functional MR imaging was also used to further characterize the lesion. In our patient, MR spectroscopy (MRS) displayed reversal of the normal choline/creatine and choline/N-acetyl aspartate (NAA) ratios. The spectroscopic profile demonstrated reduced NAA with elevated choline and lipid metabolites (Figure 2A). To our knowledge, only two cases of MRS of ISFT have been previously reported. Both reported an elevated peak of myoinositol as well as elevated peaks of the lipid/lactate complex. MR perfusion revealed increased relative cerebral blood volume (rCBV) when compared to the normal contralateral cerebellar white matter (Figure 2B).