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Pilocytic astrocytoma - with hemorrhage

Case contributed by Frank Gaillard
Diagnosis certain

Presentation

Sudden onset headache.

Patient Data

Age: Young adult

MRI brain

mri

There is a large cystic lesion in the posterior fossa, to the left of the midline. It has a fluid fluid level and does not attenuate on FLAIR. Intrinsic high T1 signal and peripheral hemosiderin is in keeping with blood produces. Inferiorly, a number of nodules are present which do not however demonstrate clear contrast enhancement. There are no abnormal flow voids. 

Case Discussion

In a young adult, the differential for a cystic lesion in the posterior fossa is really between a pilocytic astrocytoma and a hemangioblastoma. The absence of flow voids favors the former. Both lesions can uncommonly hemorrhage. 

The patient went on to have a resection. 

Pathology

MICROSCOPIC DESCRIPTION: The  sections show  cerebellar  tissue  containing  tumor  with greatly variable  appearances.   The  cerebellar  tissue itself  is  atrophic, with  marked gliosis.   The tumor contains  areas of organizing  old hemorrhage  and extensive areas of calcification, including a large calcified nodule as described    macroscopically.      Calcification    appears  to  relate  to proliferated, small,   thick-walled  blood  vessels.   There are  areas of proliferation  of  piloid  astrocytes, with  fine elongated  cytoplasm and fairly regular oval  nuclei, with  scattered granular  bodies and Rosenthal fibers evident.   In  places   there  is a  well   developed   fascicular architecture.  Neither mitotic figures  nor microvascular proliferation are apparent.   

FINAL DIAGNOSIS: Pilocytic astrocytoma, WHO grade 1.

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