La d A 7-year-old presented with a white pupillary reflex for which enucleation was done. The histopathological examination of the specimen showed Flexner Winterstein rosettes. What is the most likely diagnosis?

Explanation

## Correct Answer: D. Retinoblastoma Retinoblastoma is the most common intraocular malignancy in children, presenting with **leukocoria** (white pupillary reflex or "cat's eye reflex") in 60% of cases. The histopathological hallmark is the presence of **Flexner-Winterstein rosettes**, which are primitive neural structures formed by photoreceptor-like cells arranged around a central lumen. These rosettes are pathognomonic for retinoblastoma and distinguish it from other neural tumours. The clinical presentation of a 7-year-old with white pupil reflex (leukocoria) is classic for retinoblastoma; enucleation is performed when the eye is blind and painful or when there is no hope of vision preservation. Histopathology confirming Flexner-Winterstein rosettes (along with Perivascular rosettes and Homer Wright rosettes) definitively establishes the diagnosis. In India, retinoblastoma accounts for 3–4% of childhood cancers and is a leading cause of childhood blindness. Early detection through screening and prompt treatment (chemotherapy, radiotherapy, or enucleation) have improved survival rates significantly in tertiary centres. ## Why the other options are wrong **A. Rhabdomyosarcoma** — Rhabdomyosarcoma is a soft-tissue sarcoma that can occur in the orbit or eyelid but does NOT arise from the retina itself. It presents as orbital mass with proptosis and lid swelling, not leukocoria. Histology shows cross-striations and desmin positivity, NOT Flexner-Winterstein rosettes. This is a common trap for students confusing orbital tumours with intraocular ones. **B. Medulloblastoma** — Medulloblastoma is a cerebellar tumour in children, not an ocular lesion. While it can show rosette formation (Homer Wright rosettes), it arises from the posterior fossa, not the retina. Leukocoria is NOT a presenting feature of medulloblastoma. The clinical context of white pupil reflex and enucleation specimen rules this out entirely. **C. Astrocytoma** — Astrocytoma is a CNS tumour arising from astrocytes, typically in the brain or optic nerve. While retinal astrocytomas exist, they are rare and typically benign. They do NOT produce Flexner-Winterstein rosettes (which are specific to retinoblastoma). Astrocytomas show GFAP positivity and glial fibrillary structures, not neural rosettes characteristic of retinoblastoma. ## High-Yield Facts - **Leukocoria** (white pupil reflex) is the most common presenting sign of retinoblastoma in children, occurring in ~60% of cases. - **Flexner-Winterstein rosettes** are pathognomonic histological structures in retinoblastoma—primitive neural rosettes with a central lumen lined by photoreceptor-like cells. - **Retinoblastoma** is the most common intraocular malignancy in children and accounts for 3–4% of childhood cancers in India. - **Enucleation** is indicated when the eye is blind, painful, or has no salvageable vision; chemotherapy and radiotherapy are used for vision-preserving approaches in bilateral or early-stage disease. - **RB1 gene mutation** (chromosome 13q14) is responsible for retinoblastoma; ~40% are bilateral or familial, requiring genetic counselling and screening of siblings. ## Mnemonics **FWR = Flexner-Winterstein Rosettes** FWR is the pathognomonic histological finding in retinoblastoma. Remember: **F**lexner-**W**intersteinrosettes = **R**etinoblastoma. Use this when you see 'rosettes' + 'child' + 'white pupil' in a question. **LEUKO = Leukocoria** **LEUKO**coria (white pupil) is the classic presentation of retinoblastoma. When you see 'white pupil' or 'cat's eye reflex' in a 7-year-old, think retinoblastoma first. ## NBE Trap NBE pairs "rosette formation" with medulloblastoma to trap students who know rosettes are seen in CNS tumours but forget that Flexner-Winterstein rosettes are SPECIFIC to retinoblastoma, not medulloblastoma (which shows Homer Wright rosettes). The clinical context of leukocoria and enucleation specimen should anchor the answer to retinoblastoma. ## Clinical Pearl In Indian paediatric practice, any child presenting with leukocoria (white pupil reflex) or strabismus should undergo urgent dilated fundoscopy and imaging (ultrasound B-scan, MRI) to rule out retinoblastoma. Early detection before extraocular spread is critical for vision preservation and survival—many cases in India are diagnosed late due to delayed presentation and limited access to screening in rural areas. _Reference: Robbins Ch. 29 (Neoplasms of the Eye); Harrison Ch. 375 (Neoplastic Diseases of the Eye)_