Background:
Retinoblastoma is the most common primary ocular
malignancy of childhood.
The first description of a tumor resembling retinoblastoma was by Peter
Pawius of Amsterdam. He wrote of a malignancy invading the orbit, the temporal
region, and the cranium, a picture now strongly suggestive of untreated
retinoblastoma. The tumor was described to be filled with a "substance similar
to brain tissue mixed with thick blood and like crushed stone."
In 1805, William Hey coined the term fungus haematodes, which he used to
describe a fungating mass affecting the globe of the eye and destroying its
internal organization.
In 1809, the Scottish surgeon James Wardrop pieced together the random
isolated facts and observations of previous authors. Despite not having a
microscope at his disposal, his meticulous dissection and astute interpretations
of some of these eyes led him to conclude that in most instances the tumor arose
from the retina. Wardrop documented the extension of the tumor to the optic
nerve and brain. Later, he described metastasis to different parts of the body.
In 1836, Langenbech, Robin, and Nystin of Paris confirmed by microscopic
studies that the tumor definitely arose from the retina.
In 1864, Virchow named it a glioma of the retina, supporting glial cells as
the cell of origin of the tumor.
In 1891, Flexner of Johns Hopkins was first to notice rosettes within the
tumor. A few years later in 1897, Wintersteiner concurred with Flexner and
proposed the name neuroepithelioma noting its resemblance to rods and cones and
traced one tumor to the photoreceptor cell layer. Presently, their names are
attached to these rosettes.
Most cells comprising the tumor histologically resembled the cells of an
undifferentiated retina of the embryo called retinoblasts. This resemblance
prompted Veorhoff to coin the term retinoblastoma, which later was adopted by
the American Ophthalmological Society in 1926 as a general term for this entity.
In 1970, Tso and colleagues established that the tumor arises from
photoreceptor precursors.
Pathophysiology:
The most widely held concept of
histogenesis of retinoblastoma holds that it generally arises from a
multipotential precursor cell (mutation in the long arm of chromosome 13 band
13q14) that could develop into almost any type of inner or outer retinal cell.
Intraocularly, it exhibits a variety of growth patterns, which classically have
been described, as outlined below. (See
