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Eye: Retinoma

Written2012-03Helen Dimaras
Division of Hematology, Oncology, The Hospital for Sick Children, Toronto, ON, Canada

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Identity

Atlas_Id 5049
Phylum Head and Neck: Eye::Retinoma
Other namesRetinocytoma
Note Retinoma is the benign precursor to the childhood eye tumor, retinoblastoma. In rare cases, it remains benign for the lifetime of the individual, never progressing to retinoblastoma. Retinoma has three (3) characteristic clinical features: a grey, translucent mass in the retina; cottage cheese-like calcification; and a hyperplastic retinal epithelium/chorioretinal scar (Gallie et al., 1982). Vitreous seeds have also been observed associated with retinoma (Lueder et al., 1995).
Retinoma showing classic features of chorioretinal scar, translucent retinal mass and calcification.

Clinics and Pathology

Note The diagnosis of retinoma is made by clinical observation. Evidence of retinoma in eyes removed for retinoblastoma is often observed by histology (Dimaras et al., 2008; Eagle, 2009), and sometimes clinically after treatment of the overlying retinoblastoma tumor (Dimaras et al., 2009).
Epidemiology Retinoma has been observed clinically in 1.8% (Gallie et al., 1982) to 3.2% (Abouzeid et al., 2012) of retinoblastoma cases and by pathology in 15.6% (Dimaras et al., 2008) to 20.4% (Eagle, 2009) of enucleated retinoblastoma specimens.
Pathology Retinoma is histologically distinct from its malignant counterpart, retinoblastoma. Retinoma displays abundant fleurettes, eosinophilic cytoplasm, foci of calcification and non-proliferative cells (Margo et al., 1983; Dimaras et al., 2008). Retinoma lacks the typical features of retinoblastoma (Homer Wright and Flexner-Wintersteiner rosettes, nuclear molding, abundant mitoses and necroses), and is often observed adjacent to retinoblastoma tumor in enucleated specimens (Dimaras et al., 2008).
 
Retinoma histology showing abundant fleurettes and sparse cells with eosinophilic cytoplasm.
Treatment Frequent ophthalmic examination monitors for potential malignant progression. Malignant progression is more common in children with retinoma than in adults. In a child, the physician may opt to treat retinoma as retinoblastoma if there is even a minor suspicion of malignant progression.
Evolution Because retinomas share the same genetic origin as retinoblastoma and are frequently observed adjacent to retinoblastoma in pathological specimens, it is hypothesized that every retinoblastoma passes through a retinoma stage. However, rare retinomas do not ever progress to retinoblastoma. The difference between the retinomas that progress to malignancy and those that do not is unknown. Benign cystic growth has also been observed in some retinomas (Sampieri et al., 2008; Abouzeid et al., 2012).
Prognosis Retinoma is by definition benign and does not pose any threat to life, thought it may interfere with vision. Regular examination of rare individuals with retinoma is necessary to spot any sign of malignant transformation to retinoblastoma.

Cytogenetics

Note Retinomas identified histologically adjacent to retinoblastomas have been studied by FISH. Retinomas display low level genomic copy number changes in several genes altered to a higher degree in adjacent retinoblastoma tumors (Gain: KIF14, DEK, E2F3, MYCN; Loss: CDH11), suggesting a shared origin (Dimaras et al., 2008). The altered copy number changes in retinoma are not manifested at the expression level as in retinoblastoma.

Genes involved and Proteins

Note Like retinoblastoma, retinoma is initiated by the loss of both copies of the RB1 tumor suppressor gene.
Gene NameRB1 (retinoblastoma)
Location 13q14.2
Note Retinoma is initiated by the loss of both copies of the RB1 gene. Adjacent specimens of retinoblastoma and retinoma display the same mutation(s) in RB1 (Dimaras et al., 2008).
Dna / Rna DNA: 27 exons, 180 kb genomic DNA; RNA: 4840 bp mRNA transcript.
Protein 928 amino acid phosphoprotein.

Gene NameCDKN2A (cyclin dependent kinase 2a / p16)
Location 9p21.3
Note Retinoma is marked by upregulation of p16INK4A mRNA and protein, which is not observed in retinoblastoma. The upregulation of the senescence-associated protein may account for the non-proliferative nature of retinoma (Dimaras et al., 2008).
Dna / Rna DNA: 3 exons, 6.6 kb genomic DNA; RNA: 471 bp mRNA transcript.
Protein 156 amino acid protein.

Bibliography

Phenotypic variability of retinocytomas: preregression and postregression growth patterns.
Abouzeid H, Balmer A, Moulin AP, Mataftsi A, Zografos L, Munier FL.
Br J Ophthalmol. 2012 Jun;96(6):884-9. Epub 2012 Feb 10.
PMID 22328814
 
Retinoma underlying retinoblastoma revealed after tumor response to 1 cycle of chemotherapy.
Dimaras H, Khetan V, Halliday W, Heon E, Chan HS, Gallie BL.
Arch Ophthalmol. 2009 Aug;127(8):1066-8.
PMID 19667353
 
High-risk features and tumor differentiation in retinoblastoma: a retrospective histopathologic study.
Eagle RC Jr.
Arch Pathol Lab Med. 2009 Aug;133(8):1203-9.
PMID 19653710
 
Retinoma: spontaneous regression of retinoblastoma or benign manifestation of the mutation?
Gallie BL, Ellsworth RM, Abramson DH, Phillips RA.
Br J Cancer. 1982 Apr;45(4):513-21.
PMID 7073943
 
Retinoma associated with vitreous seeding.
Lueder GT, Heon E, Gallie BL.
Am J Ophthalmol. 1995 Apr;119(4):522-3.
PMID 7709984
 
Retinocytoma. A benign variant of retinoblastoma.
Margo C, Hidayat A, Kopelman J, Zimmerman LE.
Arch Ophthalmol. 1983 Oct;101(10):1519-31.
PMID 6626001
 
Genomic differences between retinoma and retinoblastoma.
Sampieri K, Mencarelli MA, Epistolato MC, Toti P, Lazzi S, Bruttini M, De Francesco S, Longo I, Meloni I, Mari F, Acquaviva A, Hadjistilianou T, Renieri A, Ariani F.
Acta Oncol. 2008;47(8):1483-92.
PMID 18785023
 

Citation

This paper should be referenced as such :
Dimaras, H
Head, Neck: Retinoma
Atlas Genet Cytogenet Oncol Haematol. 2012;16(9):680-682.
Free journal version : [ pdf ]   [ DOI ]
On line version : http://AtlasGeneticsOncology.org/Tumors/RetinomaID5049.html


Other genes implicated (Data extracted from papers in the Atlas) [ 1 ]

Genes KIF14

External links

arrayMap arrayMap ((UZH-SIB Zurich)   [auto + random 100 samples .. if exist ]   [tabulated segments]
 
 
Disease databaseEye: Retinoma
REVIEW articlesautomatic search in PubMed
Last year articlesautomatic search in PubMed


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