Case Study 40Henry Armah, M.D., M.Phil.

Question 1Clinical history: 40-year-old female with complaint of low back pain radiating to the lower extremities. Describe the abnormal spinal MRI findings?

Sag T2

Sag T1+C

AnswerIntradural intramedullary heterogenously contrast enhancing mass behind the L2 vertebral body.

Question 2What are your differential diagnoses based on the patients’ age and the radiological findings?

Answer1. Ependymoma

a. Myxopapillary

b. Cellular

c. Giant Cell

d. Tanycytic

2. Subependymoma

3. Astrocytomaa

. Diffuse

b. Pilocytic

4. Paraganglioma

Question 3The neurosurgeon performs a L1-2 decompressive laminectomy with resection of the focally encapsulated mass within the cauda equina and/or conus medullaris, and requested an intraoperative consultation. Describe the microscopic findings on this frozen section slide?

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AnswerNeoplasm composed of monomorphic round-to-oval glial cells with focal perivascular pseudorosettes and myxoid degeneration.

Question 4

What is your intraoperative diagnosis? (A: Category such as Defer, Reactive/Non-neoplastic, or Neoplastic; B: More specific diagnosis or statement)

AnswerA. Neoplasm

B. Myxopapillary Ependymoma

Question 5The permanent section has returned from histology. Describe the microscopic findings on this H&E slide?

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AnswerNeoplastic proliferation of monomorphic round-to-oval glial cells forming perivascular pseudorosettes with the tumor cells radially arranged in a vaguely papillary manner around vascularized stromal cores with focal mucoid/myxoid degeneration. The tumor cells show only mild pleomorphism. There are extensive areas of hyalinization and sclerotic vascularized stroma, especially on the periphery suggesting focal encapsulation. There is no evidence of mitotic figures, necrosis, anaplasia, or endothelial proliferation.

Question 6What additional immunohistochemical studies would you need to confirm the final diagnosis in this case?

Answer1. GFAP

2. EMA

3. Ki-67

Question 7What do you see on this GFAP immunostain slide?

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AnswerGFAP is strongly and diffusely positive in the neoplastic glial cell processes radiating to vessel walls.

Question 8What do you see on this EMA immunostain slide?

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AnswerEMA is negative in the tumor.

Question 9What do you see on this Ki-67 (MIB-1) immunostain slide?

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AnswerKi-67 (MIB-1) is positive in the nuclei of 1-2% of the tumor cells.

Question 10What is your final diagnosis in this case?

AnswerMyxopapillary Ependymoma

Question 11What is the corresponding WHO grade of this lesion?

AnswerWHO Grade 1