Rossets are not seen in

Discussion in 'AIIMS Nov 2013' started by samuel, Dec 14, 2014.

  1. samuel

    samuel New Member

    Rossets are not seen in:
    a) Retinoblastoma
    b) Medulloblastoma
    c) PNET
    d) Neuro-cysticercosis
    Answer: Neuro-cysticercosis

    Explanation:
    Rosettes are little round groupings of cells
    found in tumors. They usually consist of cells in
    a spoke-wheel or halo arrangement
    surrounding a central, acellular region.
    Homer Wright rosette:
    1. This rosette is typically seen in
    neuroblastoma, Medulloblastoma, and primitive
    neuroectodermal tumors (PNETs).
    2. It consists of a halo of tumor cells
    surrounding a central region containing
    neuropil (hence its association with tumors of
    neuronal origin).
    Flexner-Wintersteiner Rosette:
    1. This rosette is characteristic of
    retinoblastomas. It consists of tumor cells
    surrounding a central lumen that contains
    cytoplasmic extensions from the tumor cells.
    True Ependymal Rosette:
    1. This rosette is seen in ependymoma and
    consists of tumor cells surrounding an empty
    lumen.
    Peri-vascular Pseudo-rosette:
    1. This rosette consists of tumor cells collected
    around a blood vessel. It’s called a pseudo-
    rosette because the central structure isn’t part
    of the tumor.
    2. These rosettes are common in
    ependymomas, but also see in
    medulloblastoma, PNET, central neurocytomas,
    and glioblastomas.

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