Retinal Disorders
retinoblastoma Figure 5-37.╇ Retinoblastoma demonstrating discrete round tumor. (From Kaiser PK, Friedman NJ, Pineda II, R: Massachusetts Eye and Ear Infirmary Illustrated Manual of Ophthalmology, 2nd edn, Philadelphia, WB Saunders, 2004.)
Figure 5-38.╇ Homer-Wright rosettes. (From Augsburger JJ, Bornfeld M, Giblin ME: Retinoblastoma. In Yanoff M, Duker JS [eds]: Ophthalmology, London, Mosby, 1999.)
Exophytic: arises from outer retina and grows toward choroid causing solid RD; can extend through sclera; can simulate Coats’ disease or traumatic RD Tumor necrosis when outgrows blood supply, then calcification (seen on CT and ultrasound); may develop NV glaucoma (17%); no macular tumors after 1.5 months of age
ON involvement: present in 29% of enucleated eyes
Risk for ON invasion: exophytic tumors >15╯mm, and eyes that have secondary glaucoma
Second tumors: commonly present around age 17; osteogenic sarcoma of femur (most common), malignant melanoma of eye or orbit, leiomyosarcoma of eye or orbit, lymphoma, leukemia, rhabdomyosarcoma, medulloblastoma
Trilateral retinoblastoma: bilateral RB with a pinealoblastoma or parasellar neuroblastoma; occurs in 3% of children with unilateral RB and 8% with bilateral RB; 95% have a positive family history and / or other tumors; spontaneous regression occurs with subsequent necrosis and phthisis
Pathology: rosettes are histologic markers for tumor differentiation In order of increasing differentiation: Homer-Wright rosette: no lumen; nuclei surround tangle of neural filaments; reflects low-grade neuroblastic differentiation; can be found in other types of neuroblastic tumors (adrenal neuroblastoma, medulloblastoma) (Figure 5-38) Flexner-Wintersteiner rosette: ring of single row of columnar cells around central lumen; cells have eosinophilic cytoplasm and peripheral nuclei; photoreceptors contain cilia with a 9 + 0 pattern; represent early retinal differentiation; attempt of outer photoreceptor production; special stains show hyaluronidase-resistant acid mucopolysaccharides in lumen; also present in medulloepitheliomas (Figure 5-39)
Figure 5-39.╇ Flexner-Wintersteiner rosettes. (From Augsburger JJ, Bornfeld M, Giblin ME: Retinoblastoma. In Yanoff M, Duker JS [eds]: Ophthalmology, London, Mosby, 1999.)
Fleurettes: bouquet of pink bulbous neoplastic photoreceptor inner segments; highest degree of differentiation in retinoblastoma; found in relatively eosinophilic areas of tumor (photoreceptor differentiation) Pseudorosettes: circumferential arrangements of viable tumor cells surrounding a central vessel Cells have round, spindle-shaped hyperchromatic nuclei and very little cytoplasm; high mitotic activity; as tumor grows, outgrows blood supply creating necrosis with areas of calcification (80%) H&E stain: BLUE AREAS: represent viable tumor; differentiated cells that have basophilic nuclei and little cytoplasm PINK AREAS: represent necrotic tumor; lose basophilic nuclei and appear eosinophilic (pink) PURPLE AREAS: represent calcified tumor; occur in necrotic areas; calcium stains purple (Figure 5-40)
DDx: (DDx of leukocoria): cataract, retrolental mass (PHPV, ROP, Norrie’s disease, RD), tumor (choroidal metastases, retinal astrocytoma), exudates (FEVR, Coats’ disease, Eales’ disease), change in retinal pigment (incontinentia pigmenti, high myopia, myelinated nerve
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