1/30/2007 Case 4: Atypical astrocytic neoplasm

Clinical History:

A cerebellar mass was incidentally discovered in a neurologically normal 2 year old boy who was being worked up for short stature. The mass as seen by MRI was non-cystic, well circumscribed, hyperdense, and with minimal contrast enhancement. There was some surrounding "edema" but there was no compression of the fourth ventricle. A complete excision was achieved.

Diagnostic Notes:

The circulated slide showed a glial neoplasm with some elongate piloid astrocytes, but no biphasic spongy/compact pattern. In some areas it appeared that normal parenchyma may have been infiltrated. There was mild to no more than moderate atypia, and the cell density was low to at worst moderate. However there were easily found mitotic figures, and Dr Rao reported and showed that a MIB1 immunostain showed a high proliferative index.

Discussion centered around diagnoses of pilocytic astrocytoma versus anaplastic astrocytoma. Emphasis was placed on the clinical setting, of a child with a cerebellar tumor with some piloid features. Some in the room refused to accept a diagnosis of pilocytic astrocytoma, but then among those there was disagreement as to whether the child should receive adjunctive therapy given an apparent gross total excision.

Dr Rosenblum had been sent the case and offered a diagnosis of Atypical Astrocytic Neoplasm with a "worrisome level of proliferative activity". He declined to use the diagnosis of JPA and equally that of anaplastic astrocytoma.

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