Department of Pathology, University of Oklahoma Health Sciences Center

NeuroTest Sample Question #60 Back to NeuroTest Previous question

Answer: B (Meningioma)  Level of difficulty: 3 NeuroTest NeuroLearn NeuroHelp

Discussion: 

• Pathology of the case: The radiologic information is very useful. "Superficially located, frontal mass" is not too much of a help. "A rim of high T2 signal separate the mass from the the brain parenchyma" indicates that the tumor is not inside the brain parenchymal (so-called "extraxial"). This is highly suggestive of a meningioma or dural based tumor. Homogeneous enhancement is typical for meningioma. These radiologic features are highly suggestive of a meningioma although a dural based tumor such as solitary fibrous tumor and metastatic dural based carcinoma can also fit. Cytologically, the tumor cells have small to medium sized, rather monotonous nuclei. They do have a moderate amount of cytoplasm. In contrast to the cytoplasm of glial neoplasm that have characteristic elongated cytoplasmic process, the cytoplasm of the tumor cells are very well defined and the processes are short. I like to call these sickle-knife shaped cytoplasmic processes. A nuclear groove is present in some nuclei (ß). Pseudonuclear inclusion, another commonly seen feature in meningioma are not here. These two nuclear features are suggestive but far from diagnostic for meningioma. The most diagnostic structure is the formation of cellular whorls (ß). To increase the challenge level of this case, I did not include the best formed whorls. [Click here to see a better formed whorl] [Click here to see a whorl with psammoma body] These whorls may not be present in every case and tend to be found in cases with meningothelial pattern. When present, they are diagnostic for meningiomas. [Clicl here to see histology of a meningothelial meningioma] Meningiomas have rich diversification in architectural pattern. The characteristics of these pattern may be well reflected in the cytologic preparations. [Click here to see a meningioma case] [Click here to see another meningioma case with cytologic preparation]
• Metastatic adenocarcinoma: Metastatic adenocarcinoma, particularly those without necrosis and with bland morphology, may be confused with meningioma. In most cases, metastatic adenocarcinoma have more prominent nucleoli. The cytoplasm may appear bubbly in those with mucin production. They tend for form irregular clusters and cells arranged in the whorls that are typical for meningiomas should not be present. [Click here to see a metastatic renal cell carcinoma and compare the irregular cell cluster to the  whorls of meningioma]
• Metastatic melanoma: Metastatic melanoma and meningioma share the common feature of pseudonuclear inclusion. However, metastatic melanoma have significantly more nuclear pleomorphism. Prominent nucleoli are also common. [Click here to see a melanoma]
• Lymphoma: They appear as monotonous cells in smears and do not form cellular whorls. [Click here to see a lymphoma]
• Oligodendroglioma: Similar to other glial neoplasms, oligodendrogliomas have long cytoplasmic processes. Their nuclei tend to appear more monotonous then other glial neoplasms. However, they could be easily separated from meningiomas. [Click here to see a cyotologic preparation of an oligodendroglioma]

Comment: KarMing-Fung@ouhsc.edu