WBR0613

Author	[[PageAuthor::Rim Halaby, M.D. [1]]]
Exam Type	ExamType::USMLE Step 1
Main Category	MainCategory::Pathology
Sub Category	SubCategory::Neurology
Prompt	[[Prompt::A 10-year-old child was brought by his mother to the neurology clinic for worsening chronic headache and gait disturbance. A well-circumscribed mass with solid and cystic component is detected in the cerebellar region on CT-scan. Shown below is a pathology image of the tumor following resection. The tumor is most likely derived from cells that have which of the following functions? ]]
Answer A	AnswerA::Reactive gliosis
Answer A Explanation	[[AnswerAExp::Astrocytes play a role in reactive gliosis.]]
Answer B	AnswerB::Phagocytosis
Answer B Explanation	[[AnswerBExp::Microglia play a role in phagocytosis.]]
Answer C	AnswerC::Myelin production
Answer C Explanation	[[AnswerCExp::Schwann cells and oligodendrocytes produce myelin.]]
Answer D	AnswerD::Action potential generation
Answer D Explanation	[[AnswerDExp::Neurons are responsible for the generation and propagation of action potentials.]]
Answer E	AnswerE::Production of CSF
Answer E Explanation	[[AnswerEExp::Ependymal cells in the inner lining of the ventricles produce CSF.]]
Right Answer	RightAnswer::A
Explanation	[[Explanation::The age of the patient, the location of the mass in the cerebellar lesion and the cystic and solid characteristic of tumor increase the suspicion of a pilocytic astrocytoma. The pathology image of the tumor reveals Rosenthal fibers which are eosinophilic corkscrew fibers that are found in pilocytic astrocytoma. The diagnosis can be confirmed with GFAP staining. Astrocytes play a role in the maintenance of the blood brain barrier, regulation of potassium metabolism and reactive gliosis. Shown below is an image depicting Rosenthal fibers. Educational Objective: Pilocytic astrocytoma is a tumor arising from astrocytes and usually affects children. It is commonly located in the posterior fossa, but can be found in the supratentorial area. It is pathologically characterized by the presence of Rosenthal fibers which are eosinophilic corkscrew fibers. Astrocytes play a role in the maintenance of the blood brain barrier, regulation of potassium metabolism and reactive gliosis. References: First Aid 2014 page 489]]
Approved	Approved::No
Keyword	WBRKeyword::Pilocytic astrocytoma, WBRKeyword::brain tumor, WBRKeyword::astrocytes, WBRKeyword::reactive glioma
Linked Question	Linked::
Order in Linked Questions	LinkedOrder::