Department of Pathology, University of Oklahoma Health Sciences Center

NeuroTest Sample Question #48 Next question Previous question

Answer: C (Medulloblastoma)  Level of difficulty: 2 NeuroTest NeuroLearn NeuroHelp

Discussion: 

• Pathology of the case: Cells spread out nicely. The nuclei are round and had a dirty "salt and pepper" like chromatin. Nuceoli are not readily seen. There is a mild variation in size. Some nuclei are grooved (Þ). Many nuclei are naked. A thin rim of cytoplasm is seen in the remaining cells (Þ). The cytologic features, the age and location of the tumor are very suggestive of a medulloblastoma.
• Langerhans' histiocytosis: The cerebellum is an extremely rare location for primary or secondary Langerhans's histiocytosis. The neoplastic Langerhan's cell has characteristic nuclear groove and do not usually exhibit the degree of pleomorphism being illustrated here. In addition, Langerhans's histiocytosis are accompanied by some acute and chronic inflammatory cells and eosinophils in most cases. These  cells are entirely lacking here. [Click here to see Langerhans's histiocytosis]
• Atypical teratoid/ rhabdoid tumor: 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. For this reason, rhabdoid cells must be carefully search and the personal experience of the author is that the cytologic preparation is a very good tool for this purpose. AT/RTs 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. This provide an effective mean in separating medulloblastoma and AT/RT in questionable cases. [Click here to see a similar case]
• Ependymoma: The age and location are hightly compatible with ependymoma. .In contrast to medulloblastomas, ependymoma typically have elongated cytoplasmic process. The nuclei of ependymoma tend to be more monotonous. open and with clumpy chromatin. Small and indistinct nucleoli are common findings.. [Click here to see comparison of cytologic features] [Click here to see an ependymoma]
• Ewing's sarcoma: Primary Ewing's sarcoma in the cerebellum is extremely rare if it exists at all. Metastatic lesions, however, can occur. Similar to medulloblastoma, Ewing's sarcoma also appear as small blue cells. The large amount of glycogen in the Ewing's sarcoma cells may lead to cytoplasmic bubble formation. [Click here to see a cytologic preparation of Ewing's sarcoma from the spine, cytoplasmic bubbles are illustrated by arrow]. This feature is very subtle and is best appreciated in DiffQick stained sections. Although helpful, this feature is not consistent or every very reproducible. Ewing's sarcoma carry characteristic t(11;22)(q24;q12) translocation and is a helpful diagnostic tool.

Comment: KarMing-Fung@ouhsc.edu