Department of Pathology, University of Oklahoma Health Sciences Center

NeuroTest Sample Question #52 Next question Previous question

Answer: A (Pilocytic astrocytoma) Level of difficulty: 3 NeuroTest NeuroLearn NeuroHelp

Discussion: 

• Pathology of the case: The tumor cells here clearly bear some hair like, long stretches of cytoplasmic processes. The nuclei have open chromatid and lack pleomophism. These features are highly suggestive of a glial neoplasm. These features, however, are not diagnostic of pilocytic astrocytoma although this preparation is obtained from a pilocytic astrocytoma. [Click here to see the case]
• Meningioma: Meningioma occuring as an intraxial mass in children is extremely rare. Meningioma cells in cytologic preparations tend to stay in clusters with an epithelioid appearance and they tend to have pseudonuclear inclusion. The cytoplasm of meningioma cannot be usually be stretched to such a long an thin process on cytologic preparation.
• Germinoma: They are characterized by a mixture of large and small cells. The large cells are the germinoma cells are large, atypical, have large nuclei and prominent nucleoli. The small cells are lymphocytes. These are not the features here.
• Atypical teratoid/ rhabdoid tumor (AT/RT): This is a histologic grade IV/IV tumor in the World Health Organization (WHO) classification. The characteristic rhabdoid cells are large, round a hyalinized globule that display the nucleus to the periphery.  The nuclei are pleomorphic, large, and have prominent nucleoli. It is essentially a primary rhaboid tumor of the central nervous system that may occur with or without non-rhabdoid element. The most common associated non-rhabdoid elements are medulloblastoma-like neoplastic component. They occur most commonly in infants under three years of age, they are highly aggressive, and most of them are associated with deletion of chromosome 22q where the INI1 gene is located. [Click here to see a case of AT/RT]
• Medulloblastoma: Medulloblastoma tends to occur in young children and infants and they occur in the cerebellum. The cells in cytologic preparations appear as small blue cell tumor with a minimal rim of cytoplasm. Many of the nuclei are naked. In general the nuclei are relatively monotonous but a higher degree of variation in nucelar size can be appreciated in the cytologic preparations than frozen sections or paraffin sections. Typically, the nuclei have a dirty "salt and pepper" suggestive of neuroendocrine differentiation. Nuclear groove can be seen in some nuclei. Medulloblastoma do not arrange in papillary structures as in this case. The tumor cells in this case has too much cytoplasm and the nuclei lacks the characteristic "salt and pepper" neuroendocrine appearance. These are not features in this case. [Click here to see comparison of cytologic features].

Comment: KarMing-Fung@ouhsc.edu