Department of Pathology, University of Oklahoma Health Sciences Center

NeuroTest Question #14 Next question Previous question

Answer: D (Pleomorphic xanthoastrocytoma) Level of difficulty: 3 NeuroTest NeuroLearn NeuroHelp

Discussion: 

• Lesion under discussion: The lesional tissue is composed of neoplastic cells with substantial pleomorphism. The salient diagnostic clue is the large cell with foamy cytoplasm located at the upper part of the field; a typical feature in pleomorphic xanthoastrocytoma (PXA).
• Dyembryoplastic neuroepithelial tumor (DNET): The histology can be quite variable but the large cells and cytologic atypia being shown here is not a feature of DNET.
• Large cell medulloblastoma: Large cell medulloblastoma essentially maintains the appearance of medulloblastoma but with large nuclei and increased pleomorphism. The large nucleus in large cell medulloblastoma often "hug" on a smaller nucleus. The tumor being illustrated here has no resemblance to medulloblastoma.
• Pleomorphic xanthoastrochtoma (PXA): This is an uncommon tumor that accounts for less than 1% of all astrocytic tumors; most of them are seen in children and young adults. Although they have favorable prognosis, about one-fifth of the cases may have malignant transformation. They tend to occur in supratentorial locations as superficial tumors with leptomenigeal involvement. Histologically, there is a variegated appearance of the tumor with spindly elements intermingled with mono- or multinucleated giant cellls, the nuclei of which display great variation in size and staining. Mitotic activity is not very conspicuous, if present. Necrosis is not seen. As being illustrated here, there is intracellular accumulation of lipid droplets that often occupy much of the cell body; the nuclei and the more basophilic cytoplasm are often pushed to the side. As a result, immunostaining often demonstrate crescents of cytoplasm that are immunoreactive for GFAP. Reticulin fibers can be well demonstrated in the tumor and in leptomeninges being invaded by tumor cells.

Comment: KarMing-Fung@ouhsc.edu