Retinoblastoma pathophysiology
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Simrat Sarai, M.D. [2]
|
Retinoblastoma Microchapters |
|
Diagnosis |
|---|
|
Treatment |
|
Case Studies |
|
Retinoblastoma pathophysiology On the Web |
|
American Roentgen Ray Society Images of Retinoblastoma pathophysiology |
|
Risk calculators and risk factors for Retinoblastoma pathophysiology |
Overview
On gross pathology, viable tumor cells near blood vessels and zones of necrosis in avascular areas are characteristic findings of retinoblastoma. On microscopic histopathological analysis, small round-cell tumor of neuroepithelial origin, Flexner-Wintersteiner rosettes and Homer-Wright rosettes are characteristic findings of retinoblastoma.
Pathophysiology
Usually retinoblastoma is caused by mutational inactivation of both alleles of the retinoblastoma (RB1) gene [31]. The RB1 gene maps to chromosome 13q14 and encodes a nuclear protein (Rb) that acts as a tumor suppressor [30,32-34]. This protein (Rb) restricts the cell's ability to progress from the G1 phase to the S phase of the cell cycle [35]. Rb binds to E2F, a transcription factor, when active. Loss of this active, functional protein (Rb) causes cell cycle dysregulation.
Gross Pathology
Macroscopically, viable tumor cells are found near blood vessels, while zones of necrosis are found in relatively avascular areas. Macroscopic examination reveals a white elevated mass with fine surface vessels. Early retinoblastoma presents as a solitary or multifocal, well-circumscribed translucent mass. The tumor becomes more pink in color, with dilated feeding blood vessels, as the disease advances. The tumor may exhibit three patterns of growth:[1]
| Growth patterns | Features |
|---|---|
|
|
|
|
|
|
Microscopic Pathology
Microscopically, both undifferentiated and differentiated elements may be present:[2]
- Undifferentiated elements appear as collections of small, round cells with hyperchromatic nuclei.
- Differentiated elements include:
- Flexner-Wintersteiner rosettes
- Homer-Wright rosettes
- Fluerettes from photoreceptor differentiation
See also
References
- ↑ Retinoblastoma. Radiopedia(2015) http://radiopaedia.org/articles/retinoblastoma
- ↑ Retinoblastoma. Wikipedia(2015) https://en.wikipedia.org/wiki/Retinoblastoma Accessed on October 10 2015