An 80-year-old right-handed man with a history of hypertension and stable coronary artery disease presented with progressive lethargy, confusion, and unsteadiness. Four months previously, he had been admitted to the stroke service following the abrupt onset of severe headache, nausea, vomiting, and ataxia. An axial computed tomographic (CT) scan showed a 3 × 3-cm left cerebellar hemorrhage; magnetic resonance imaging was not performed. He was managed nonoperatively for hypertension-induced intracerebral hemorrhage, transferred to a rehabilitation hospital 1 week later, and discharged at 2 weeks with a normal neurological status.Three months later, the patient noted difficulty in coordinating his walking. Repeat noncontrast axial CT showed a resolving hematoma with minimal mass effect; there was no hydrocephalus. He was stable until 1 week prior to admission, at which point he became diffusely weaker, lethargic, and withdrawn. On the day before admission, he became abruptly more confused and was unable to walk. A nonenhanced CT scan revealed increased cerebellar edema. The patient was transferred to our hospital and steroids were administered, with clinical improvement. Neurological examination noted lethargy, lateral gaze nystagmus, and left hand dysdiadochokinesia. Magnetic resonance imaging, including axial T1-weighted, axial T1-weighted with gadolinium (Figure, A), and coronal, T1-weighted gadolinium-enhanced, demonstrated a solid, homogeneously enhancing 4.5 × 3.5-cm mass in the vermis and left cerebellar hemisphere with associated edema, mass effect, and resolving hemorrhage. Physical examination and detailed CT imaging of the chest, abdomen, and pelvis revealed no primary neoplasm.The patient underwent a suboccipital craniectomy. At surgery, a discrete, firm, pseudoencapsulated mass in the vermis and medial left cerebellum was encountered; there was no attachment to the pia or dura. Contrast and non–contrast-enhanced axial views 1 day postsurgery indicated that gross total resection was accomplished. The patient tolerated surgery and was discharged 4 days later. He was to receive radiation therapy to a total of 60 cGy.Hematoxylin-eosin, reticulin, and glial fibrillary acidic protein (GFAP)–immunostained sections of fixed tissue revealed a predominantly sarcomatous neoplasm populated by fascicles of spindle cells that often appeared to be associated with the adventitia of blood vessels (Figure, B). Mitotic activity in these fascicles was brisk. Reticulin stains and immunohistochemical analysis demonstrated extensive reticulin but no GFAP, HMB-45, desmin, or myoglobin immunoreactivity (Figure, C and D). Neither rhabdomyoblasts nor strap cells were found. Interspersed were islands of anaplastic GFAP-immunoreactive astrocytes with scattered mitoses. Multifocal necrosis was also present.What is your diagnosis?Gliosarcomas are uncommon malignant primary tumors of the brain that contain both glial and mesenchymal elements. They are most commonly encountered in the frontal, temporal, and parietal lobes in patients older than 60 years of age.1–6 Only rare cases of gliosarcomas have been reported in the cerebellum. These include 2 cases that occurred after radiation treatment of extracranial neoplasms78 and 2 primary gliosarcomas of the cerebellum in patients who were 62 and 71 years of age.910 One of these demonstrated multiple homogeneously enhancing masses on contrast-enhanced T1-weighted magnetic resonance images; each mass had extensive contact with the dura mater.9 Computed tomography of the other case demonstrated a single contrast-enhancing lesion that proved upon operation to have an attachment to the tentorium cerebelli. Typically, enhanced T1-weighted MR images of cerebral gliosarcomas demonstrate diffuse, inhomogeneous enhancement or irregular ringlike enhancement.4 Our case and that report by Nitta et al9 indicate that a pattern of more homogeneous enhancement may be encountered in primary gliosarcoma of the posterior fossa.Cerebral gliosarcomas show a predilection for a superficial location and dural invasion and thus may not be considered in the initial workup of parenchymal masses, as depicted here.4 Our case illustrates that gliosarcoma should be included in the differential diagnosis of deep lesions, such as other gliomas and metastatic lesions that present without dural involvement.The diagnosis of gliosarcoma rests on the exclusion of glioblastomas associated with reactive leptomeningeal or vascular changes and sarcomas with entrapped reactive astrocytes. Diagnosis requires identification of a malignant glial (usually astrocytic) component and at least one ×100 magnification field of a sarcoma histologically consistent with a malignant fibrous histiocytoma or fibrosarcoma. Although the source of the sarcomatous component has been debated, Boerman et al6 have now identified similar genetic alterations (ie, gains of chromosome 7, deletions of 9p, and losses of chromosome 10 in both the glial and sarcomatous components), indicating that this component arises from the same progenitor cell as the glial component.We conclude that sporadic primary gliosarcomas may involve the cerebellum in the very old with atypical radioimaging characteristics. Given the rarity of this tumor and the variability of its radiographic appearance, the diagnosis may be apparent only upon biopsy of the lesion.
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Mar 1, 2021
Chun-Yu Chen + 1
Open Access