A child successfully treated for bilateral hereditary retinoblastoma develops a mass in the pineal region three years later, histologically similar to the ocular tumors. What is this entity called, and through which structure does spread occur?
- A Trilateral retinoblastoma, via primitive photoreceptor cells of the pineal gland sharing the same germ line mutation ✓
- B Trilateral retinoblastoma, via the optic nerve
- C Metastatic retinoblastoma, via hematogenous dissemination
- D Secondary osteosarcoma, due to external beam radiotherapy
Correct answer: A. Trilateral retinoblastoma, via primitive photoreceptor cells of the pineal gland sharing the same germ line mutation
Explanation
Trilateral retinoblastoma is the occurrence of an intracranial neuroblastic tumor, usually a pineoblastoma or suprasellar primitive neuroectodermal tumor, in a child with bilateral or hereditary retinoblastoma. It arises from the photosensitive cells of the pineal gland, which share embryonic origin with retinal photoreceptors and carry the same germline RB1 mutation. It is not metastatic spread, and radiation-associated second malignancies such as osteosarcoma arise outside the skull midline years later in irradiated fields.
Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.