Skip to content

Cancer Health Center

Font Size

Retinoblastoma Treatment (PDQ®): Treatment - Health Professional Information [NCI] - Tumor Pathology of Retinoblastoma

Retinoblastoma arises from the photoreceptor elements of the inner layer of the retina. Microscopically, the appearance of retinoblastoma depends on the degree of differentiation. Undifferentiated retinoblastoma is composed of small, round, densely packed cells with hypochromatic nuclei and scant cytoplasm. Several degrees of photoreceptor differentiation have been described and are characterized by distinctive arrangements of tumor cells. The Flexner-Wintersteiner rosettes are specific for retinoblastoma; these structures consist of a cluster of low, columnar cells arranged around a central lumen that is bounded by an eosinophilic membrane analogous to the external membrane of the normal retina. The lumen contains an acid mucopolysaccharide similar to that found around normal rods and cones. These rosettes are seen in 70% of tumors. Homer-Wright rosettes, on the other hand, are composed of irregular circlets of tumor cells arranged around a tangle of fibrils with no lumen or internal-limiting membrane. Horner-Wright rosettes are infrequently seen in retinoblastoma and are most often seen in other neuroblastic tumors, such as neuroblastoma and medulloblastoma.

Retinoblastomas are characterized by marked cell proliferation, as evidenced by high mitosis counts, extremely high MIB-1 labeling indices, and strong diffuse nuclear immunoreactivity for cone-rod homeobox, also known as CRX, a useful marker to discriminate retinoblastoma from other malignant, small, round cell tumors.[1,2]

Recommended Related to Cancer


This complementary and alternative medicine (CAM) information summary provides an overview of the use of Essiac and Flor Essence, which are proprietary herbal tea mixtures, as treatments for people with cancer. The summary includes a brief history of the development of Essiac and Flor Essence; a review of laboratory, animal, and human studies; and possible side effects associated with Essiac and Flor Essence use. This summary contains the following key information: Essiac and Flor Essence...

Read the Overview article > >

Cavitary retinoblastoma, a rare variant of retinoblastoma, has ophthalmoscopically visible lucent cavities within the tumor. The cavitary spaces appear hollow on ultrasonography and hypofluorescent on angiography. Histopathologically, the cavitary spaces have been shown to represent areas of photoreceptor differentiation.[3] These tumors have been associated with minimal visible tumor response to chemotherapy, which is thought to be a sign of tumor differentiation.[4]


  1. Terry J, Calicchio ML, Rodriguez-Galindo C, et al.: Immunohistochemical expression of CRX in extracranial malignant small round cell tumors. Am J Surg Pathol 36 (8): 1165-9, 2012.
  2. Schwimer CJ, Prayson RA: Clinicopathologic study of retinoblastoma including MIB-1, p53, and CD99 immunohistochemistry. Ann Diagn Pathol 5 (3): 148-54, 2001.
  3. Palamar M, Pirondini C, Shields CL, et al.: Cavitary retinoblastoma: ultrasonographic and fluorescein angiographic findings in 3 cases. Arch Ophthalmol 126 (11): 1598-600, 2008.
  4. Mashayekhi A, Shields CL, Eagle RC Jr, et al.: Cavitary changes in retinoblastoma: relationship to chemoresistance. Ophthalmology 112 (6): 1145-50, 2005.

    This information is produced and provided by the National Cancer Institute (NCI). The information in this topic may have changed since it was written. For the most current information, contact the National Cancer Institute via the Internet web site at http:// cancer .gov or call 1-800-4-CANCER.

    WebMD Public Information from the National Cancer Institute

    Last Updated: May 28, 2015
    This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.
    Next Article:

    Today on WebMD

    Colorectal cancer cells
    New! I AM Not Cancer Facebook Group
    Lung cancer xray
    See it in pictures, plus read the facts.
    sauteed cherry tomatoes
    Fight cancer one plate at a time.
    Ovarian cancer illustration
    Real Cancer Perspectives
    Jennifer Goodman Linn self-portrait
    what is your cancer risk
    colorectal cancer treatment advances
    breast cancer overview slideshow
    prostate cancer overview
    lung cancer overview slideshow
    ovarian cancer overview slideshow
    Actor Michael Douglas