Neuro Teaching Set

Portions of the tissue contain large cells that are immunoreactive for placental alkaline phosphatase (PLAP). In these areas, there is also an admixture of lymphocytes.

The morphology of this neoplasm is unusual. There are giant cells present in spaces separated by paucicellular fibrillary septae containing abundant Rosenthal fibers.

The excised tumor consists of a cystic mass with both solid and thin membranous areas of the wall.

This malignant neoplasm is composed of large neoplastic lymphocytes. CD-45, CD-20, and CD-45RO are positive. CD-3 is negative.

The signs of anaplasia are very atypical neoplastic cells and focal high cell density. There are no substantial endothelial reaction or tumor necrosis evident.

The tumor is focally cellular, but mitotic figures are rare and Ki-67 is no greater than 1%. PCNA is equivocal due to technical factors.