Neuro Teaching Set

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

The lesion consists of dilated, endothelial-lined, blood-filled vascular spaces surrounded by concentric, loosely organized fibromuscular tissue.

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 EMA stain is focally positive. The Ki-67 stain shows a low proliferative rate (<1%).

This meningioma infiltrates the dura mater extensively. There is nuclear pleomorphism and rare mitotic figures. There is no necrosis.

The tumor consists of well-differentiated keratinizing squamous epithelium in a papillary architecture.

The tumor is predominantly the tall cell variant of papillary thyroid carcinoma. There is no evidence of a follicular carcinoma component in this specimen.