Late onset retinoblastoma in a child with 13 q deletion syndrome.

A nine-year-old boy presented with right leukocoria, prompting an ophthalmic evaluation that revealed an exophytic group E retinoblastoma. Initial systemic assessment revealed intellectual disability and dysmorphic facies. Conventional cytogenetic analysis of peripheral blood lymphocytes revealed male karyotype (46, XY). Fluorescence in situ hybridization (FISH) using a locus-specific probe targeting the RB1 gene at chromosome 13q14 demonstrated a deletion in approximately 90% of interphase nuclei and consequently the diagnosis of 13 q deletion was established. Chromosomal microarray identified a ~ 20-Mb deletion at 13q13.3-q21.1 (×1) and a ~ 20-Mb duplication at 13q21.31-q31.1 (×3). MRI orbit and brain showed no optic nerve or intracranial extension. Metastatic work up including CSF sample and BM aspirates was free. Due to advanced group E retinoblastoma, the decision was to perform enucleation. Subsequent histopathological examination revealed high risk features in the enucleated eye and the child received post enucleation chemotherapy. One year afterward, there are no detectable recurrences. To our knowledge, this represents one of the oldest reported cases of retinoblastoma in association with 13q deletion syndrome.