Nervous System- Tumor and Tumor-like lesion I
Question No. 17. The Answer is: (E) All of the above.
Discussion: The structures being shown here are Homer Wright rosettes. They are typically seen in extracranial neuroblastomas and, less commonly, in medulloblastomas. Although Flexner-Wintersteiner rosettes are typical for retinoblastomas, Homer Wright rosettes can also be found in some retinoblastomas. Expression of neuorendocrine markers such as synaptophysin and, less commonly, neuronal markers such as neurofilament can be seen in medulloblastomas and neuroblastomas with or without Homer Wright rosettes. Expression of photoreceptor specific antigens such as S-antigen, rod opsin, and inter-retinal binding protein (IRBP) have been well documented in medulloblastomas with or without Homer Wright rosettes.