MC intraocular malignant tumour of childhood: March 2013
**Core Concept**
Retinoblastoma is a malignant tumor of the retina, the light-sensitive tissue at the back of the eye. It is the most common primary intraocular malignancy of childhood, typically affecting children under the age of 5.
**Why the Correct Answer is Right**
Retinoblastoma arises from the primitive neuroectodermal cells of the retina. The tumor may be unilateral or bilateral and can be accompanied by leukocoria (white reflex) or strabismus. The genetic basis of retinoblastoma involves mutations in the RB1 gene, which is a tumor suppressor gene that regulates cell cycle progression. Inheritance of a mutated RB1 gene can lead to a predisposition to retinoblastoma.
**Why Each Wrong Option is Incorrect**
**Option A:** Medulloepithelioma is a rare malignant tumor of the ciliary body or iris, but it is not the most common intraocular malignancy of childhood.
**Option B:** Optic nerve glioma is a type of glioma that affects the optic nerve, but it is not typically classified as an intraocular malignancy.
**Option C:** Melanoma is a type of skin cancer that can metastasize to the eye, but it is not the most common primary intraocular malignancy of childhood.
**Clinical Pearl / High-Yield Fact**
Retinoblastoma can be treated with a combination of chemotherapy, radiation therapy, and surgery, depending on the stage and extent of the tumor. Early detection is crucial for improving prognosis and preserving vision.
**Correct Answer: D. Retinoblastoma**