Anaplastic astrocytoma NOS

Case contributed by Dr Ariel Dahan



Patient Data

Age: 70 years
Gender: Female

CT Brain


CT shows an ill-defined hyperintense lesion in the right thalamus with only minor mass effect but no surrounding edema. 

MRI Brain


Brain MRI demonstrates a right thalamic-centered lesion that also extends to the right hippocampus and tectum. It has a low T1 signal and a heterogeneous high T2 signal. It results in mild compression of the adjacent the right lateral ventricle. There is no midline shift. The remainder brain is unremarkable. 

Contrast was not administered due to allergy. 

Case Discussion

Anaplastic astrocytomas (WHO grade III) are high-grade gliomas and hence usually carry a poor prognosis. Given this patient is slightly older for the peak of incidence for these tumors (40-50 years), the differential diagnosis would include a primary CNS lymphoma. Other possible diagnoses would include low-grade gliomas or a glioblastoma. However, the absence of central non-enhancing fluid intensity regions makes the latter less likely.  

Despite there being no clinical history available for this patient, individuals with anaplastic astrocytomas, usually present in a non-specific way with one or more episodes of seizures, focal neurological deficit or intracranial hypertension; clinical presentations shared by most of the brain tumors. In this patient, the lesion was first identified on CT before being more adequately described on MR imaging and surgically resected for histopathological analysis. 

This patient went on to have a biopsy. 


The sections show cerebral tissue which is moderately hypercellular, with a diffuse infiltrate of astrocytic cells. The cell cytoplasm often has gemistocyte morphology. Nuclei are hyperchromatic and moderately pleomorphic. Occasional mitotic figures are identified in what is, overall, a small sample. There is no necrosis and definite microvascular proliferation is not seen. The features are those of diffusely infiltrating astrocytoma, WHO grade 3. No oligodendroglial component is identified.

FINAL DIAGNOSIS: Anaplastic astrocytoma (WHO grade III)

This case predates the 2016 WHO classification of brain tumors and IDH mutation status is not available. It is therefore considered an anaplasic astrocytoma NOS. 

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