1. A biopsy from the tongue shows pseudoepitheliomatous hyperplasia with histiocyte like cells underneath, which contain a granular cytoplasm. A diagnosis is suspected and confirmed with S-100 positivity. Which of the following is true with regards to this tumor:

2. EM of an undifferentiated tumor is noted to have long thin microvilli (height to width ~ 10:1). Which of the following tumors is this most consistent with:

3. EM of an undifferentiated tumor shows microvilli with long filamentous core rootlets (electron dense). This finding suggests which diagnosis:

4. Based on the findings in the images below for Case #2, which of the following is the best diagnosis?

5. EM of a CNS tumor shows prominent interdigitating processes without a basal lamina. There are well formed desmosome junctions and prominent cytoplasmic inclusions. These findings are most consistent with:

6. EM of a tumor shows rhomboid crystalline inclusions. Cytogenetics also showed a t(X;17). These findings are consistent with which of the following neoplasms?

7. Based on the findings in the image below for Case #5, which of the following is the best diagnosis?

8. A specimen being prepared for electron microscopy should be fixed in:

9. Based on the findings in the images below for Case #4, which of the following is the best diagnosis?

10. Based on the findings in the images below for Case #3, which of the following is the best diagnosis?

11. EM of a CNS tumor showed intracellular lumens lined by microvilli with specialized junctions between cells and glial features. This is most conisistant with which of the following tumors:

12. An undifferentiated tumor shows prominent profiles of rough endoplasmic reticulum. Which of the following markers would also be positive in this lesion?

13. Based on the findings in the images below for Case 1, which of the following is the best diagnosis?