tation occurs early in the developmental stage in the immature retinoblast, a .... cance of retinoma and phthisis bulbi for retinoblastoma. Ophthal- mology. 1982 ...
Short Subjects A Rare Case of Retinocytoma Occurring in a 12-Year-Old Child Aylin Yaman, MD Kaan Gündüz, MD Osman Saatci, MD Nilüfer Koçak, MD Abstract. A 12-year-old girl with a translucent, partially calcified retinal mass in the posterior pole surrounded by a rim of pigment epithelial changes and chorioretinal atrophy was diagnosed as having retinocytoma. The patient received a single treatment of transpupillary thermotherapy at the slit lamp to prevent malignant transformation. The dimensions of the lesion and the visual acuity remained unchanged at 3.5 years of follow-up with no further treatment. Retinocytoma is a benign retinal tumor that carries the same genetic implications as retinoblastoma. Regular follow-up is necessary because the tumor can demonstrate malignant transformation. J Pediatr Ophthalmol Strabismus 2008;45:49-50.
Introduction Retinocytoma or retinoma is a benign tumor of retinocytic origin that is caused by mutation of the retinoblastoma gene. This condition was first described by Gallie et al. in 1982.1 They theorized that a benign variant of retinoblastoma arises if inactivation of supressor genes occurs late in a relatively mature retinoblast and named this tumor retinoma. In contrast, if the mutation occurs early in the developmental stage in the immature retinoblast, a retinoblastoma develops. The alternate term retinocytoma was subsequently proposed by Margo et al.2 Other terms such as spontaneously regressed retinoblastoma, spontaneously arrested retinoblastoma, and retinoblastoma group 0 have also been used to describe these tumors.3-5 From the Department of Ophthalmology (AY, OS, NK), 9 Eylül University Faculty of Medicine, Izmir; and the Department of Ophthalmology (KG), Ankara University Faculty of Medicine, Ankara, Turkey. Originally submitted January 19, 2005. Accepted for publication October 12, 2005. Address correspondence to Kaan Gündüz, MD, Mesa Koza Plaza 18/24, GOP 06700, Ankara, Turkey.
Figure. Fundus photograph showing partially calcified translucent retinocytoma in the posterior pole associated with surrounding chorioretinal atrophy.
We describe the clinical features of a case with retinocytoma and elaborate on the clinical features of this entity.
Case Report A 12-year-old girl was examined due to decreased vision in the right eye. The best-corrected visual acuity was 20/200 in the right eye and 20/20 in the left eye. Anterior segment examination was normal in both eyes. Funduscopically, there was a translucent, partially calcified mass in the posterior pole that was surrounded by a rim of pigment epithelial changes and chorioretinal atrophy in the right eye (Figure). The lesion measured 8.0 3 8.0 mm in base diameter and 2.0 mm in thickness by Aand B-mode ultrasonography. Based on these clinical features, a diagnosis of retinocytoma was made. Fundus examination of the left eye was normal. Because retinocytoma has the potential to become malignant, the patient received a single treatment of transpupillary thermotherapy (3.0 mm spot size, 600 mW power, 3 minutes’ duration) at the slit lamp. There was poor heat uptake by the lesion during the procedure. The dimensions of the lesion and the visual acuity remained unchanged at 3.5 years of follow-up. No further treatment was given. Results of ocular examination of the patient’s siblings and parents were normal. The implications of this tumor for the patient’s possible offspring were explained to the patient and parents.
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Discussion Although retinocytoma is an uncommon tumor, its frequency among families with a history of retinoblastoma is higher and has been reported to vary between 1% and 10%.6-9 Singh et al. reported that the median age at diagnosis was 15 years, ranging from 4 to 45 years.9 The authors noted that the diagnosis was made in 82% of patients after 5 years of age in contrast to retinoblastoma, which is usually diagnosed in children younger than 5 years.9 The diagnosis of retinocytoma is made on the basis of a characteristic clinical appearance and absence of documented growth during the follow-up. Retinocytoma appears as a translucent retinal mass, which is commonly associated with calcification and alterations in retinal pigment epithelium.9 Other tumor features include surrounding chorioretinal atrophy and normal caliber supplying and draining blood vessels.9 Retinocytoma commonly simulates a type 3 regressed retinoblastoma, as in our case.9,10 Rarely, it can also simulate types 1, 2, and 4 regressed retinoblastoma.9,10 Retinocytoma usually presents in the midperipheral fundus, followed by the posterior equator and peripheral retina.9 In the macular area, retinocytoma usually does not involve the foveola.9 The tumor in our case also occurred in the macular area and spared the foveola. There can be multiple foci of retinocytoma in the same eye.9,11,12 Moreover, some patients may have retinoblastoma in one eye and retinocytoma in the fellow eye.6,7 The diagnosis of retinocytoma can be made in symptomatic cases based on the symptoms of visual loss or strabismus, as in our case. However, retinocytoma can also be discovered in asymptomatic patients on routine eye examination. In some cases, retinocytoma is found in patients who come for an eye examination because they have family members with retinoblastoma. Singh et al. reported that 10 of their 17 patients (59%) were asymptomatic at the time of diagnosis.9 Retinocytoma is a benign tumor and many cases remain stationary at follow-up. Retinocytoma can rarely develop progressive resorption over several years.13 The most dreaded complication of retinocytoma is malignant transformation.7-9,12 Singh et al. found that malignant transformation developed in 1 of 24 (4%) retinocytomas in their series.9 Eagle et al. previously reported the same situation with rapid enlargement of the tumor and vitreous seeding at age 7 years after a follow-up of 3 years.8 The results 50
of histopathologic examination in their case showed undifferentiated retinoblastoma in the newer elevated part of the tumor overlying the base with benign histopathologic features of retinocytoma. Vitreous seeding does not indicate malignant transformation in a retinocytoma and such cases may remain stationary for many years.12 Retinoblastoma in adults or older children may develop due to the malignant transformation of a previously unsuspected retinocytoma. Retinocytoma carries the same genetic implications as retinoblastoma. Patients with multiple or bilateral retinocytomas should be considered to have germline mutation of the retinoblastoma gene.14,15 These patients have a 45% risk of passing the gene to their children. Patients with a unifocal unilateral retinocytoma usually have a somatic mutation and these patients have a 1% risk of passing the gene to their children. Families and the patients themselves should have genetic counseling. Regular follow-up is necessary because the tumor can demonstrate malignant transformation.
References 1. Gallie BL, Phillips RA, Ellsworth RM, Abramson DH. Significance of retinoma and phthisis bulbi for retinoblastoma. Ophthalmology. 1982;89:1393-1399. 2. Margo C, Hidayat A, Kopelman J, Zimmerman LE. Retinocytoma: a benign variant of retinoblastoma. Arch Ophthalmol. 1983;101:1519-1531. 3. Aaby AA, Price RL, Zakov ZN. Spontaneously regressing retinoblastomas, retinoma or retinoblastoma group 0. Am J Ophthalmol. 1983;96:315-320. 4. Abramson DH. Retinoma, retinocytoma, and the retinoblastoma gene. Arch Ophthalmol. 1983;101:1517-1518. 5. Shields JA, Shields CL. Intraocular Tumors: A Text and Atlas. Philadelphia: W. B. Saunders; 1992:319. 6. Gallie BA, Ellsworth RM, Abramson DH, Phillips RA. Retinoma: spontaneous regression of retinoblastoma or benign manifestation of the mutation? Br J Cancer. 1982;45:513-521. 7. Balmer A, Munier F, Galloud C. Retinoma: case studies. Ophthalmic Pediatr Genet. 1991;12:131-137. 8. Eagle RC Jr, Shields JA, Donoso LA, Milner RS. Malignant transformation of spontaneously regressed retinoblastoma, retinoma/ retinocytoma variant. Ophthalmology. 1989;96:1389-1395. 9. Singh AD, Santos CM, Shields CL, Shields JA, Eagle RC Jr. Observation on 17 patients with retinocytoma. Arch Ophthalmol. 2000;118:199-205. 10. Singh AD, Garway-Heath DF, Love LS, Plowman PN, Kingston JE, Hungerford JL. Relationship of regression pattern to recurrence in retinoblastoma. Br J Ophthalmol. 1993;77:12-16. 11. Lommatzsch PK, Zimmerman W, Lommatzsch R. Spontaneous growth inhibition in retinoblastoma [article in German]. Klin Monatsbl Augenheilkd. 1993;202:218-223. 12. Lueder GT, Héon E, Gallie BL. Retinoma associated with vitreous seeding. Am J Ophthalmol. 1995;119:522-523. 13. Lam A, Shields CL, Manquez ME, Shields JA. Progressive resorption of a presumed spontaneously regressed retinoblastoma over 20 years. Retina. 2005;25:230-231. 14. Gallie BL, Dumm JM, Chan HSL, Hamel PA, Phillips RA. The genetics of retinoblastoma: relevance to the patient. Pediatr Clin North Am. 1991;38:299-315. 15. Draper GJ, Sanders BM, Brownbill PA, Hawkins MM. Patterns of risk of hereditary retinoblastoma and applications to genetic counselling. Br J Cancer. 1992;66:211-219.
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