Retinoblastoma and the 13q deletion syndrome

13q deletion syndrome and retinoblastoma in identical dichorionic diamniotic monozygotic twins

PURPOSE

To report the case of identical dichorionic diamniotic female twins with unilateral retinoblastoma in 13q deletion syndrome.

METHODS

Clinical and ophthalmoscopic evaluation, combination of multiple ligation-dependent probe amplification, array-comparative genomic hybridization analyses, and magnetic resonance imaging were performed.

RESULTS

Peculiar facial features, marked hypotonia, gastroesophageal reflux, interatrial septal defect with left to right shunt and light dilatation of right chambers, 5th finger hypoplasia, 3rd-5th toes clinodactyly, 2nd toe overlapped to 3rd toe, and cutis marmorata were found. Ophthalmoscopic evaluation revealed unilateral retinoblastoma in both girls. Magnetic resonance imaging detected corpus callosum hypoplasia in both twins. A 34.4-Mb deletion involving bands 13q13.2-q21.33 and including the RB1 gene was identified in both twins. The deletion was not present in the DNA of their parents and older brother.

CONCLUSIONS

Dysmorphic features in children must be always suspicious of 13q deletion syndrome and a short ophthalmoscopic follow-up is necessary to detect the presence of a retinoblastoma.

Brain abnormalities on MR imaging in patients with retinoblastoma

BACKGROUND AND PURPOSE

Although pineoblastoma is the main brain abnormality associated with hereditary retinoblastoma, recent studies suggest an association with pineal cysts. This association is important because some pineoblastomas mimic pineal cysts. If there is a relationship, then radiologists should be aware of it because diagnostic confusion is possible. Mental retardation and congenital brain anomalies are also reported in patients with retinoblastoma, mostly in combination with 13q deletion syndrome. In this retrospective study, the presence of brain abnormalities on MR images in a large group of consecutive patients with retinoblastoma is evaluated.

MATERIALS AND METHODS

Brain MR images of 168 patients with retinoblastoma from 1989 to 2009 were evaluated by 2 radiologists for tumors, structural anomalies, myelinization, and coincidental findings. Clinical records were reviewed for laterality, heredity, and the presence of the 13q deletion syndrome.

RESULTS

The hereditary group (patients with bilateral and unilateral proved RB1-germline mutation) included 90 (54%) of 168 patients. Seven patients had 13q deletion syndrome. Normal findings on brain MR images were seen in 150 (89%) patients. Five pineoblastomas were detected, all in patients with hereditary retinoblastoma (5.5% in the hereditary subgroup). Nine pineal cysts were detected (2.2% in the hereditary subgroup). Corpus callosum agenesis was found in 1 patient and a Dandy-Walker variant in 1 patient, both in combination with 13q deletion syndrome.

CONCLUSIONS

Pineoblastoma is associated with hereditary retinoblastoma, and structural brain abnormalities are restricted to patients with the 13q deletion syndrome. The incidence of pineal cysts in patients with retinoblastomas is similar to that in healthy children and is not associated with hereditary retinoblastoma.

Autopsy case of a patient with 13q- syndrome

Partial deletion of the long arm of chromosome 13 results in 13q(-) syndrome, and phenotypes of affected patients vary widely. We describe an autopsy case of the sudden, unexpected death of a 17-year-old boy with 13q(-) syndrome. He had severe psychomotor retardation and had been receiving follow-up care. One day he was found dead in his house and autopsy was performed to elucidate the cause of death. Autopsy findings revealed lobulation anomalies of the lungs, hypoplasia of the adrenal and thyroid glands, and apituitarism due to hyperplasia of bone in the hypophyseal fossa. No other pathological lesions were observed. Chromosomal analysis confirmed interstitial deletion from the long arm of chromosome 13. Karyotype was 46,XY, del(13)(q14.3q32). We concluded that the patient died of multi-organ dysfunction due to apituitarism. Autopsy cases of 13q(-) syndrome are rare. Furthermore, lobulation anomalies and apituitarism associated with 13q(-) syndrome have not previously been described. This case report offers novel clues to elucidating critical regions of chromosome 13 associated with malformations of the lungs and pituitary gland.

Retinoblastoma and deletion of the long arm of chromosome 13: an underestimated diagnosis?

We report an infant with normal neurological development and phenotype who developed bilateral retinoblastoma (RB). This patient, despite lack of dysmorphic features, demonstrated constitutional abnormality of the long arm of chromosome 13 on standard karyotype. We recommend systematic cytogenetic examinations complemented by fluorescent in situ hybridization as second-line screening in all patients suspected for hereditary RB despite negative RB1 molecular screening and normal phenotype.

Clinical Case Notes. Retinoblastoma, microphthalmia and the chromosome 13q deletion syndrome

A 10-month-old boy, known to have the 13q deletion syndrome, presented with leukocoria in a microphthalmic right eye. He was found to have bilateral retinoblastoma requiring enucleation of the right eye and laser, cryotherapy and external beam radiation to the left eye. This case demonstrates that retinoblastoma may be present in a microphthalmic eye and that more than one imaging modality should be used in the evaluation of suspected retinoblastoma, as calcification may be absent on the computed tomography scan but present on B-mode ultrasound. Children with a known 13q deletion require immediate and serial ophthalmological examinations.