Histopathologically rosettes are seen in

Ans. A retinoblastomaRosettes are little round groupings of cells found in tumors.Usually consist of cells in a spoke-wheel or halo arrangement surrounding a central, acellular region seen commonly in Retinoblastoma.In well-differentiated retinoblastomas, the tumor cells are characteristically arranged in rosettes. The rosettes may be of 2 types-- Flexner-Wintersteiner rosettes characterized by small tumor cells arranged around a lumen with their nuclei away from the lumen, and Homer-Wright rosettes having the radial arrangement of tumor cells around the central neurofibrillar structurePNET (Primitive Neuro-Ectodermal Tumour) :A PNET is composed of sheets of uniform small, round cells that are slightly larger than lymphocytes,Medulloblastoma:Individual tumor cells of medulloblastoma are small, with little cytoplasm and hyperchromatic nuclei that are frequently elongated or crescent-shaped