A young child presents with the eye finding shown in the image. Which of the following is the most likely diagnosis?

Explanation

## Image Findings * **Leukocoria** (white pupillary reflex) observed in the right eye (patient's left eye). * Normal black pupillary reflex present in the left eye (patient's right eye). * The image depicts a young child. ## Diagnosis **Key Point:** **Retinoblastoma**, characterized by **leukocoria** (white pupillary reflex) in a young child, which is the most common presenting sign of this malignant intraocular tumor. The image clearly demonstrates a distinct white reflex in the pupil of the right eye, a finding known as **leukocoria**, or "cat's eye reflex." This contrasts sharply with the normal dark pupillary reflex seen in the left eye. In a young child, **leukocoria** is the cardinal sign of **retinoblastoma**, a highly aggressive and potentially fatal intraocular malignancy originating from primitive retinal cells. Early detection is paramount for both vision preservation and patient survival, as untreated retinoblastoma can metastasize and lead to death. ## Differential Diagnosis | Feature | Correct Dx: Retinoblastoma | Alt 1: Congenital Cataract | Alt 2: Ocular Toxocariasis | Alt 3: Retinopathy of Prematurity (ROP) | | :------------------------ | :--------------------------------------------------------- | :--------------------------------------------------------- | :--------------------------------------------------------- | :--------------------------------------------------------- | | **Etiology** | Malignant tumor of retinal photoreceptor precursors. | Opacification of the lens; genetic, infectious (TORCH), metabolic. | Granulomatous inflammation due to *Toxocara canis* larvae. | Abnormal retinal vessel proliferation in premature infants. | | **Leukocoria Appearance** | Often a solid, chalky white mass reflex; can be multifocal. | Diffuse white or grey reflex, sometimes with specific patterns. | Localized white granuloma, often with tractional retinal detachment. | White reflex due to retinal detachment or retrolental fibroplasia. | | **Associated Features** | Strabismus, glaucoma, hyphema, orbital cellulitis (advanced). | Nystagmus, microphthalmia, other systemic anomalies (e.g., rubella). | Unilateral, often history of dog exposure, eosinophilia. | History of prematurity, low birth weight, oxygen therapy. | | **Prognosis** | Potentially fatal if untreated; good prognosis with early treatment. | Good visual prognosis if treated early, but amblyopia risk. | Vision loss due to inflammation/scarring. | Variable, can lead to severe vision loss or blindness. | ## Clinical Relevance **Clinical Pearl:** Any child presenting with **leukocoria** must be urgently referred to an ophthalmologist for a thorough dilated fundus examination to rule out **retinoblastoma**, as it is a life-threatening condition requiring prompt diagnosis and treatment. ## High-Yield for NEET PG **High-Yield:** **Leukocoria** is the most common presenting sign of **retinoblastoma**, accounting for approximately 60% of cases. **Key Point:** The **red reflex test** (Bruckner test) is a crucial screening tool for leukocoria in infants and young children, performed during routine pediatric examinations. ## Common Traps **Warning:** While other conditions like congenital cataract, ocular toxocariasis, and ROP can cause leukocoria, the most critical trap is to delay or miss the diagnosis of **retinoblastoma** due to its high mortality if untreated. Always prioritize ruling out malignancy first. ## Reference [cite:Kanski's Clinical Ophthalmology: A Systematic Approach, 9th Edition, Chapter 16: Retinal Vascular Disease and Tumours]