All are X-ray findings of retinoblastoma except –
**Core Concept**
Retinoblastoma is a malignant tumor of the retina, often presenting with characteristic X-ray findings due to the calcification within the tumor. The X-ray manifestations of retinoblastoma are crucial for early detection and diagnosis.
**Why the Correct Answer is Right**
Retinoblastoma typically presents with a characteristic "salt and pepper" appearance on X-ray due to the calcification within the tumor. This is caused by the deposition of calcium in the tumor, which can be visualized on X-ray. The calcification is often seen as multiple small, scattered opacities within the globe, resembling the appearance of salt and pepper. This is due to the high density of the calcified tumor, which is visible on X-ray.
**Why Each Wrong Option is Incorrect**
**Option A:** Typically, retinoblastoma presents with a "salt and pepper" appearance, but other retinal tumors like Coats disease may present with a "tram track" sign due to retinal detachment and calcification, but not typically as characteristic as retinoblastoma.
**Option B:** While vitreous seeds may be seen in retinoblastoma, they are not a characteristic X-ray finding.
**Option C:** Choroidal melanoma may present with a characteristic "dome-shaped" or "eggshell" calcification, but this is not a typical X-ray finding of retinoblastoma.
**Option D:** Leukokoria (white pupillary reflex) is a clinical sign of retinoblastoma, but not an X-ray finding.
**Clinical Pearl / High-Yield Fact**
Retinoblastoma is the most common primary intraocular malignancy in children, and early detection is crucial for treatment and survival. The "salt and pepper" appearance on X-ray is a classic sign of retinoblastoma, and should prompt further investigation and treatment.
**Correct Answer:** D. Leukokoria (white pupillary reflex) is a clinical sign of retinoblastoma, but not an X-ray finding.