Case of the week Details

• Images 1: Axial T2 and T1 images demonstrate a T2/T1 hyperintense right intraocular mass with large exophytic component, distorting the right globe with proptosis.
• Images 2: Axial T2 and T1 images demonstrate well-defined extra-axial mass lesion in suprasellar region with internal cystic changes.
• Images 3: Oblique sagittal STIR and T2 sagittal images demonstrate extra-scleral extension of lesion along right optic nerve involving the optic chiasma and contiguity with the supra-sellar lesion.
• Images 4: Axial SWI and ADC images demonstrate hyperintensity on DWI with corresponding dark signal on ADC in the intraocular and suprasellar lesion.
• Image 5: Coronal T2 image demonstrates pachy and leptomeningeal spread of lesion along right frontal lobe

DIAGNOSIS:

Right ocular Retinoblastoma – Group F

Discussion:

• Most common intraocular tumor of childhood associated with mutation of Rb1 gene on chromosome 13.
• They can be sporadic (60%) and hereditary (40%).
• Hereditary cases have increased risk of developing osteosarcoma, soft tissue sarcoma, and melanoma in later life.
• Retinoblastoma is classified as:
  1. Unilateral: One globe.
  2. Bilateral: Both globes.
  3. Trilateral: Both globes + Pineal/Suprasellar lesion.
  4. Quadrilateral: Both globes + Pineal + suprasellar.
• MRI is mainstay for diagnosis and grouping of lesion.
• Grouping of lesion is based on International classification of Retinoblastoma.
• Lesions can demonstrate calcifications.
• Important checkpoints are subretinal seeding, choroidal invasion, and scleral / extra-scleral invasion and CNS involvement.
• Choroidal invasion and optic nerve extension are poor prognostic features.

DIFFERENTIAL DIAGNOSIS:

• Coats disease: Absence of calcification or enhancement.
• Persistent Fetal Vasculature: Retrolental mass which demonstrates enhancement and extends into Hyaloid canal.
• Retinal Astrocytic hamartoma: Associated with tuberous sclerosis. Imaging features include exudative retinal detachment, hemorrhage and calcification. Lesion is non-progressive.

REFERENCES:

1. Andreas M, Chirag V, Kristen W, High-Resolution MR Imaging of the Orbit in Patients with Retinoblastoma, RadioGraphics 2012; 32:1307–1326. https://doi.org/10.1148/rg.325115176.

Dr. Anita Nagadi
MD, MRCPCH (UK), FRCR (UK), CCT (UK)
Senior Consultant Radiologist
Columbia Asia Radiology Group.

Dr. Akshay K
DNB Resident
Columbia Asia Radiology Group.