Retinocytoma Associated with Calcified Vitreous Deposits

PURPOSE

To report a case of bilateral retinocytoma associated with calcified vitreous deposits.

METHODS

Case report.

RESULTS

On routine examination, a 35-year-old asymptomatic father of a child with bilateral retinoblastoma presented bilateral retinocytoma associated with vitreous calcifications, in the vicinity of the retinocytoma in his left eye. Fundus photographic documentation and fluorescein angiography were performed. The patient has been followed up for 10 years.

CONCLUSIONS

The lesions in both eyes have remained stable without signs of growth or malignant transformation. Calcified vitreous deposits are a recently described feature of retinocytoma in addition to the three classic features: translucent retinal mass, retinal pigment epithelial alteration, and calcification.

Loss of RB1 induces non-proliferative retinoma: increasing genomic instability correlates with progression to retinoblastoma

Retinoblastoma clinical observations revealed the role of tumor suppressor genes in human cancer, Knudson's 'two-hit' model of cancer induction. We now demonstrate that loss of both RB1 tumor suppressor gene alleles initiates quiescent RB1(-/-) retinomas with low level genomic instability and high expression of the senescence-associated proteins p16(INK4a) and p130. Although retinomas can remain unchanged throughout life, highly proliferative, clonal and aneuploid retinoblastomas commonly emerge, exhibiting altered gene copy number and expression of oncogenes (MYCN, E2F3, DEK, KIF14 and MDM4) and tumor suppressor genes (CDH11, p75(NTR)) and reduced expression of p16(INK4a) and p130. We suggest that RB1 inactivation in developing retina induces genomic instability, but senescence can block transformation at the stage of retinoma. However, stable retinoma is rarely clinically observed because progressive genomic instability commonly leads to highly proliferative retinoblastoma.