In retinoblastoma, 'trilateral retinoblastoma' refers to which combination?

• A Bilateral retinoblastoma with metastasis to the liver
• B Bilateral retinoblastoma with an associated intracranial midline (pineal or suprasellar) PNET ✓
• C Unilateral retinoblastoma with bilateral optic nerve involvement
• D Retinoblastoma with osteosarcoma and melanoma (three primary tumours in germline carriers)

Explanation

Trilateral retinoblastoma consists of bilateral retinoblastoma plus an intracranial primary neuroectodermal tumour (PNET), usually in the pineal gland (pineoblastoma) or suprasellar/parasellar region. It occurs in germline RB1 mutation carriers. The intracranial component arises from undifferentiated neuroectodermal cells in midline structures that share susceptibility to RB1 loss. It carries a very poor prognosis. Germline carriers are also at risk of secondary osteosarcoma (with radiation), but that is separate from trilateral retinoblastoma.

Reference: Khurana Comprehensive Ophthalmology, 7th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.