Retinoblastoma

Findings

CT of the orbits with contrast demonstrates 7 x 4 mm mildly enhancing left retinal mass with associated focal, coarse calcification.

Differential diagnosis:
- Retinoblastoma
- Retinoma – benign variant
- Persistent hyperplastic primary vitreous
- Retrolental fibroplasia
- Toxocariasis (no calcification)
- Coat's disease


Diagnosis: Retinoblastoma


Key points

Rare, malignant, congenital tumor – arises from neuroectodermal cells of retina.
Clinical findings – leukocoria 60 % (reflection from white mass within the eye, giving the appearance of a white pupil)
Incidence – 1:15k – 1:34k live births. Most common intraocular neoplasm in childhood; 1% of all childhood malignancies.
70% < 3 years of age; mean age of presentation - 18 months.
30% bilateral, 30% multifocal within one eye
66% non heritable form; Heritable sporadic form (20-25%); 10% familial history of retinoblastoma


Radiology

Intraocular mass
High density (calcification, hemorrhage); enhancement usual
Dense vitreous humor (commonly)
Calcifications (90%); in absence of calcification, suspect other mass lesions

Primary role of imaging is to determine tumor spread:
- Optic nerve extension (25%)
- Scleral break-through
- Metastases; meninges, liver, lymph nodes