Rossettes are characteristically seen in -

Ans. is 'a' i.e., Retinoblastoma Rosettes Rosettes are pathological findings characterized by a halo or spoke wheel arrangement of cells surrounding a central core or hub. Type of Rosette Flexner - Wintersteiner Rosettes o A halo of cells surrounds a largely empty central hub but small cytoplasmic extension from cells project into the lumen. o It is characteristic of retinoblastoma. o May also be seen in --> Medulloblastoma, Primitive neuroectodermal tumor, Pineoblastoma. Homer Wright rosettes o A halo of cells surrounds a central hub that contains a meshwork of fibres (neutrophil rich centre). o Homer-Wright rosettes are characteristic of neuroblastomas and medulloblastomas. o May also be seen in --> Primitive neuroectodermal tumors (PNET), Pineoblastomas, Retinoblastomas. True ependymal Rosette o A halo of cells surrounds an empty lumen. o It is characteristic of ependymomas. Perivascular pseudorosettes o A halo of cells surrounds a blood vessel. o The term pseudo is used because the central structure is not formed from the tumor itself, and represents a nonneoplastic element. o May be seen in - Ependymonas Glioblastomas Medulloblastomas Retinoblastoma Primitive neuroectodermal tumors Monimorphous pilimyxoid astrocytoma Central neurocytoma