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

Question 1 Clinical 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

Answer Intradural intramedullary heterogenously contrast enhancing mass behind the L2 vertebral body.

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

Answer Ependymoma Subependymoma Astrocytoma Paraganglioma a. Myxopapillary b. Cellular c. Giant Cell d. Tanycytic Subependymoma Astrocytoma a. Diffuse b. Pilocytic Paraganglioma

Question 3 The 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? Click here to view slide.

Answer Neoplasm 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)

Answer Neoplasm Myxopapillary Ependymoma

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

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

Answer GFAP EMA Ki-67

Question 7 What do you see on this GFAP immunostain slide? Click here to view slide.

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

Question 8 What do you see on this EMA immunostain slide? Click here to view slide.

Answer EMA is negative in the tumor.

Question 9 What do you see on this Ki-67 (MIB-1) immunostain slide? Click here to view slide.

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

Question 10 What is your final diagnosis in this case?

Answer Myxopapillary Ependymoma

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

Answer WHO Grade 1