Retinoblastoma

Retinoblastoma presentation

1. RETINOBLASTOMA By Dr. Ayush Garg

2. Clinical Anatomy The eye is composed of three layers. Outer fibrous layer formed by the sclera posteriorly and the cornea anteriorly. Inner layer , sensory retina with vision concentrated at the fovea which is lateral to the optic nerve and directly posterior to the lens. In between these vascular layer – the uvea or choroid –which supplies the retina. The iris is the outer continuation of the vascular layer Lens sits just behind iris, suspended from the ciliary body. No lymphatic drainage

3. PATHOLOGY Flexner Wintersteiner rosettes -columnar cells around a central lumen -also seen in med u l l o e p i th e lioma Homer Wright -rosettes around a central neuromuscular core -neuroblastoma, medul l oe p itheli o m a, medulloblastomas Fleurettes Tumor cells with pear shaped eosinophilic processes projecting through

4. LE U K OCORIA

5. FUNDOSCOPIC EXAMINATION Typical appearance of intraretinal retinoblastoma. Opaque, yellow-white macular tumor fed and drained by dilated, tortuous retinal blood vessels.

6. RETINOMA -spontaneously arrested retinoblastoma Limited vascularity Gre y i sh -white Speckled Surrounding chorio-retinal atrophy RPE hypertrophy

7. A computed tomography scan of a large calcified retinoblastoma in the right eye.

8. Transaxial T2-weighted (TR/TE, 3,460/116  ms ) ( a ) and T1-weighted (TR/TE, 374/14  ms ) precontrast ( b ) and postcontrast ( c ) MRI of exophytically growing retinoblastoma with secondary retinal detachment. Retinoblastoma typically has low signal intensity compared to the vitreous body on T2-weighted images and intermediate signal intensity on precontrast T1-weighted images, and it demonstrates marked contrast enhancement

9. ROUTES OF SPREAD

10. O RBITAL IMPLANT

11. RADIOACTIVE PLAQUE APPLICATION Procedure: 1 st USG of eye done: for tumor dimensions: maximum basal diameter, max height → surgical exploration → applicators are applied over sclera overlying the tumor → 1.5-2 mm margin on either side of basal diameter → retention sutures → Rx → Re-exploration for removal of plaques

12. Iodine 125 plaques

13. Ruthen i um plaque sutured to sclera

14. PATTERNS OF GROWTH

15. Radiotherapy

16. External beam radiotherapy Indications Multi-focal retinoblastoma RB close to macula or optic nerve Large tumor with vitreous seeding Positioning Proper immobilization is important thermoplastic or Perspex shell with the patient supine and the chin in a neutral position Treatment is done under anesthesia: Ketamine Energy: Co-60 or 4-6 MV photons

17. Technique Lateral field technique Started in 1930’s D – shaped lateral field with anterior border kept at bony orbit Disadvantage: tumor recurrence at or near ora serrata Modified lateral beam technique Two lateral opposed D-shaped fields are used

18. Direct Anterior Field [Hungerford et al ] Whole eye is treated Disadvantage: Cataract formation Dose exits through brain Lacrimal gland irradiation-impaired tear production Advantages: Simple, easy to setup Reproducible Homogenously irradiates entire retina Anterior lens sparing technique (ALD) [Abramson et al ] Lateral D-shaped field: Day1-Day 4 by photons Anterior electron beam field with central circular contact lens as lens shaped shield: on Day 5

19. Unilateral disease: one lateral field or 2 oblique portals [superior and inferior] Bilateral disease: parallel opposed lateral fields The anterior beam edge is placed at the bony canthus and the beam is angled 1.5 degrees posteriorly if the contralateral eye remains in place.

20. Dose Ideal: 40-45 Gy , 1.8-2 Gy per fraction, 5 days a week For large tumor /vitreous seeding: 48-50 Gy Palliative radiotherapy: Extra-ocular involvement: 20-25 Gy Metastatic disease: CNS, bones: 5 Gy /1#, 15 Gy /3# Unilateral : single lateral field With anterior extension: anterior field + lateral field tilted 5-15° posteriorly Bilateral disease: parallel opposed lateral fields

21. 3D CONFORMAL RADIOTHERAPY TECHNIQUE Based on 3D CT scan planning In unilateral RB, 4 non-coplanar fields are used. fields are anterior oblique: superior, inferior, medial, and lateral. 0.5-cm bolus can be used. entire retina should be treated, including 5 to 8 mm of the proximal optic nerve. Critical structures such as the opposite eye, optic chiasm, pituitary gland, brainstem, posteriormost upper teeth, and upper cervical spine. The tumor volume is treated to the 98% or 95% line,with the aforementioned organs and tissues receiving significantly less dose.

22. bilateral disease, six noncoplanar fields are used: two lateral opposing, and two anterior oblique fields to each eye following the same criteria described previously. 3D CT scan reconstruction image showing beam arrangement for unilateral RB : anterior medial and lateral fields (A), anterior superior and inferior fields (B), sagittal view of composite isodose distribution (C), and axial transverse view of isodose distribution (D)

23. Follow up 1 st 6 months: 4-6 week intervals Upto 3 years: at 4-6 month intervals Later, yearly Family history positive: All family members [other children at birth] should be examined yearly

24. THANK YOU