Case Study 31

1. Case Study 31 Julia Kofler, M.D.

2. A 6-year-old boy was followed for several years for a slowly growing brain lesion. Describe the findings in his MRI scan.

6. Homogeneously contrast-enhancing mass in the frontal horn of the left lateral ventricle Minimal mass effect with slight shift of the septum pellucidum A smaller contrast-enhancing mass is also seen in the frontal horn of the right lateral ventricle (best seen on the axial image) No evidence of surrounding brain edema No evidence of hydrocephalus

7. Question 2 What is your differential diagnosis based on the imaging findings?

8. Answer Ependymoma Subependymal giant cell astrocytoma Choroid plexus tumors Pilocytic astrocytoma Central neurocytoma Meningioma Subependymoma is usually non-enhancing

9. Question 3 A resection of the mass was performed. Describe the findings in the following representative permanent H&E slide. Click here to view slide.

10. Answer Clusters of polygonal cells with abundant glassy cytoplasm and eccentric nuclei with prominent nucleoli Tumor cells vary in size; giant cells and multinucleated cells are present Tumor cells are embedded in fibrillary background Focal perivascular pseudopalisading Rare mitotic figures are present Scattered infiltrating mast cells are noted No necrosis or vascular endothelial proliferation is present

11. Question 4 Representative images of immunohistochemical stains can be seen in the following figure. The Ki-67 proliferation index was 1-3%. What is your diagnosis?

13. Answer Subependymal giant cell astrocytoma

14. Question 5 Throughout the tumor, there are scattered cells with a different morphology and pale blue cytoplasm as highlighted in the following figure. What are these cells? Which stain was used to highlight them? Which immunohistochemical stains could be used to highlight these cells

16. Answer Mast cells Giemsa stain Tryptase or CD117 (c-kit)

17. Question 6 Further review of the patient�s MRI scan reveals additional findings. The patient also has a history of seizures. Describe the radiologic findings and give the most likely diagnosis.

21. Answer Multifocal subcortical T2/flair hyperintensities and minimal thickening of the overlying cortex Cortical tubers

22. Question 7 Other clinical features in this patient include an asymptomatic cardiac tumor, mild learning disability and multiple white patches on his skin. Based on the clinical, radiological and pathological findings, what is your diagnosis? What is the most likely diagnosis for the patient�s cardiac tumor?

23. Answer Tuberous sclerosis Cardiac rhabdomyoma

24. Question 8 Which genetic test would you order to confirm you diagnosis?

25. Answer Mutational analysis of TSC1 and TSC2 genes, encoding for hamartin and tuberin.

26. Question 9 Name the major clinical features of tuberous sclerosis.

27. Answer Facial angiofibromas Nontraumatic ungual or periungual fibroma Hypomelanotic macules (>3) Shagreen patch Retinal nodular hamartomas Cortical tubers Subependymal nodules Subependymal giant cell astrocytoma Cardiac rhabdomyoma Lymphangiomatosis Renal angiomyolipoma

28. Question 10 What are the histopathologic findings in a cortical tuber?

29. Answer Giant cells (similar to subependymal giant cell astrocytoma) Dysmorphic neurons Dysmorphic neurons and giant cells may be seen in all cortical layers and underlying white matter Disrupted cortical lamination Gliosis Calcification of blood vessel walls and/or parenchyma Myelin loss