Atypical presentations of intracranial dysgerminoma mimicking central nervous system inflammatory or demyelinating disease.

OBJECTIVES: The aim of this study is to report a case series of atypical presentations of intracranial dysgerminoma in which the diagnosis was delayed due to clinical and radiographic findings initially suggestive of CNS inflammatory or demyelinating diseases, such as MS. METHODS: This study is a case series detailing the history, clinical presentations, radiographic and laboratory results, and management of three patients with biopsy-proven intracranial dysgerminoma. RESULTS: All three patients demonstrated hyperintense lesions on MRI that were more suggestive of demyelinating or inflammatory diseases, including lesions involving the midbrain and corpus callosum. All three patients were serum positive for oligoclonal bands and negative for both AFP and beta-hCG (these two markers are commonly seen in dysgerminoma cases). One case involved a steroid-responsive tumor whereas the other two cases either did not respond to steroids or steroids were withheld due to uncertainty of etiology. Following biopsy, all three results were consistent with dysgerminoma. CONCLUSION: Clinicians should be aware that dysgerminoma may mimic the clinical and radiographic presentations of demyelinating diseases such as MS. These lesions can cause acute visual loss or diplopia, have MRI and CSF findings that might mimic MS, and have been shown to respond to steroids. Atypical clinical (e.g., headache, dorsal midbrain syndrome, bilateral optic neuropathy) or atypical radiographic features (e.g., mass effect, hydrocephalus) should prompt consideration for repeat imaging and possible biopsy even if serum or CSF tumor markers (beta-hCG and AFP) are negative for dysgerminoma.

Sacroiliac joint vacuum phenomenon--underreported finding.

BACKGROUND AND PURPOSE: Vacuum phenomenon (VP) is commonly found in sacroiliac joints, and its significance in patients with back pain has been debated. We investigated the prevalence of sacroiliac joint vacuum phenomenon (SJVP) and the rate at which it is reported on abdominopelvic and lumbosacral spine computed tomography (CT) images by body imagers and neuroradiologists. We hypothesized that it would be more common than not and that neuroradiologists would identify it more frequently than body imagers and on spine images more commonly than abdominopelvic studies due to the search for the source of back pain in the former. MATERIALS AND METHODS: CT images of the pelvis and lumbar spine from January to February 2009 were retrospectively reviewed. Six hundred fifty-two patients were studied during this period. Axial thin-section images were reviewed under default lung and bone window settings. Age, sex, and radiologist reports were assessed from electronic medical records. RESULTS: The prevalence of SJVP on CT imaging was 34%, with higher rates found in female (41%, P<.001) and older (39%, P<.05) patients. Eighty-five percent of the phenomena were present bilaterally. Among the 223 patients with SJVP, only 17% were reported. There were no statistically significant differences between reporting rates for body radiologists and neuroradiologists. CONCLUSION: SJVP is a prevalent condition with higher rates among older and female individuals. The phenomenon is underreported on CT images whether the studies performed are abdominopelvic scans or spine studies and whether they are interpreted by body imagers or neuroradiologists.