From the Department of Ophthalmology, University Hospital La Paz, Madrid, Spain.
The authors have no financial or proprietary interest in the materials presented herein.
Address correspondence to Anna Grabowska, MD, Department of Ophthalmology, University Hospital La Paz, Paseo Castellana 261, Madrid, 28046 Spain. E-mail: email@example.com
Coats’ disease is one of the most common conditions simulating retinoblastoma.1 Because both conditions may present in young children with the triad of total retinal detachment, subretinal mass or exudation, and abnormal retinal vessels, clinical differential diagnosis may be difficult.2
Contrast enhanced magnetic resonance imaging (MRI) is the method of choice and should be used to answer any clinical questions.3 It has proven superior to computed tomography (CT) in differentiating primary retinal detachment such as Coats’ disease from secondary retinal detachment due to a possible underlying tumor such as retinoblastoma.4 According to some authors, post-contrast T1-weighted images are reliable in differentiating a solid neoplastic tumor from nonsolid retinal detachment or hemorrhage.3
In this article, we outline a case of advanced Coats’ disease in which MRI findings led to diagnostic confusion. We also discuss the role of MRI in the differential diagnosis between retinoblastoma and advanced Coats’ disease.
A 6-year-old boy presented in the emergency department with a few days’ history of red and painful right eye. Medical, ocular, and family history for retinoblastoma or other ocular diseases was unremarkable.
The affected eye had uncorrected distance visual acuity of light perception. Variable exotropia was present. Pupillary examination demonstrated an afferent pupillary defect.
Slit-lamp examination of the right eye revealed mixed conjunctival injection, severe corneal edema, iris neovascularization, and an intraocular pressure of 36 mm Hg. Ocular examination of the left eye was normal. Funduscopy was impossible due to media opacity. On ultrasonography, the retina appeared detached with a medium to highly reflective mass in its temporal part.
Unenhanced T1-weighted images (Fig. 1A) showed total retinal detachment with the subretinal space occupied by heterogeneous material that was hyperintense compared to the vitreous of the normal eye. T2-weighted images (Fig. 1B) showed membranous structures forming a V in the papilla and temporal quadrant. The detached retina appeared hypointense, thickened, and irregular, with hypointense subretinal fluid. There was a distinct, hypointense nodular lesion in its temporal side measuring 5 mm in diameter. Contrast-enhanced series showed marked enhancement of retinal leaflets and nodular lesions (Fig. 1C). The optic nerve, episclera, contralateral eye, pineal region, and midline structures appeared normal. Diffuse infiltrating retinoblastoma was the suspected diagnosis, but Coats’ disease and other simulating lesions could not be ruled out.
Figure 1. Magnetic Resonance Imaging Findings. (A) Axial Unenhanced T1-Weighted Image. There is Total Retinal Detachment with the Subretinal Space Occupied by Heterogeneous Material, Hyperintense Compared to the Vitreous of the Normal Eye. (B) Axial Unenhanced T2-Weighted Image. Note the Overall Decrease in Signal Intensity. The Detached Retina Appears Hypointense; the Nodular Lesion and the Subretinal Fluid Are Hypointense Compared to the Vitreous of the Normal Eye. (C) Axial Enhanced T1-Weighted Image. Note the Enhancement of Retinal Detached Leaflets and the Nodular Lesions.
After enucleation, histologic examination (Fig. 2) revealed total exudative retinal detachment. The subretinal fluid was predominantly hemorrhagic; lipid-laden macrophages, lipid deposition, and areas of recent hemorrhage were present. In addition to the other findings, the presence of telangiectasic retinal vessels led to the final diagnosis of Coats’ disease.
Figure 2. Histologic Examination Revealed Total Exudative Retinal Detachment. (A) Note the Presence of Telangiectasic Retinal Vessels (arrows) (hematoxylin–Eosin, Original Magnification ×10). (B) The Subretinal Fluid is Predominantly Hemorrhagic; Lipid-Laden Macrophages and Cholesterol Crystals are Present (arrows) (Hematoxylin–Eosin, Original Magnification ×40).
Advanced Coats’ disease is distinguished by total exudative retinal detachment following leakage from congenital retinal telangiectasias.5 If left untreated, it usually progresses to the development of rubeosis iridis and painful neovascular glaucoma, often requiring enucleation. It may be difficult to distinguish from retinoblastoma, especially when media opacity renders retinal visualization impossible.
Ultrasonography, CT, and MRI are the methods of choice when there are doubts arising from clinical examination.3,6 The detection of intraocular calcifications is relevant to the differentiation of retinoblastoma from simulating lesions. Histology reports show that 95% of retinoblastomas calcify.7 CT has a sensitivity of 96% in detecting calcification in retinoblastoma, whereas MRI sensitivity is 91.7%.8 Ultrasonography aids in the detection of intraocular masses and calcification, but is not useful in assessing tumor extent. Generally, MRI is required to detect optic nerve, scleral, and choroid infiltration, as well as extraocular or intracranial disease extension. CT is still the best method of detecting intraocular calcifications, but concern over the cumulative biological effects of radiation makes MRI the safer and thus preferred method.9 Its higher contrast and resolution, as well as multiplanar imaging, aid in the evaluation of tumor extent and detection of metastasis.
On MRI evaluation, patients with advanced Coats’ disease generally have been reported to have homogeneous subretinal fluid of high intensity on both T1- and T2-weighted images.10 The detached thickened retina has been described as a curvilinear hypointense line arising from the optic disc on both T1- and T2-weighted images, showing minimal enhancement in post-contrast sequences. Subretinal fluid does not enhance. Lai et al.10 reported a case of advanced Coats’ disease with hypointense subretinal fluid in T2-weighted images and post-contrast enhancement of the detached retina with a locally nodular appearance.
Some authors claim that low signal images on T2-weighted images are rare in Coats’ disease compared to retinoblastoma.11 Typical MRI findings of retinoblastoma are described as high signal intensity at T1-weighted images and low signal intensity at T2-weighted images. On post-contrast images, the subretinal liquid does not show enhancement but the tumor does. Calcifications are a common finding in retinoblastoma, although usually difficult to find on MRI studies. Brisse et al.12 reported two cases of diffuse infiltrating retinoblastoma showing retinal detachment with hyperintense retinal fluid in unenhanced T1- and T2-weighted images and hypointense, diffusely thickened, irregular detached retina in T2-weighted images. Contrast-enhanced sequences showed marked enhancement of retinal leaflets with a locally nodular appearance.
Diffuse infiltrating retinoblastoma is a rare intraretinal growth pattern of retinoblastoma that can simulate inflammatory or hemorrhagic conditions. Its characteristic lack of tumor mass and calcification, occurrence in older patients, and presentation at an advanced stage may present real diagnostic problems.13
Our case highlights the similarities of MRI findings in diffuse infiltrating retinoblastoma and advanced Coats’ disease. We have attempted to demonstrate that differentiating between the two may be impossible, particularly when ophthalmoscopic examination is not possible and there is no calcification on sonographic or CT examination. It could be concluded that the presence of any irregularities and nodules within the thickened retina on MRI may indicate retinoblastoma; however, enhancement of the detached retina and nodular lesions does not confirm the diagnosis.
- Shields JA, Parsons HM, Shields CL, Shah P. Lesions simulating retinoblastoma. J Pediatr Ophthalmol Strabismus. 1991;28:338–340.
- Shields JA, Shields CL. Differentiation of Coats’ disease and retinoblastoma. J Pediatr Ophthalmol Strabismus. 2001;38:262–266.
- Potter PD, Shields CL, Shields JA, Flanders AE. The role of magnetic resonance imaging in children with intraocular tumors and simulating lesions. Ophthalmology. 1996;103:1774–1783.
- Beets-Tan RG, Hendriks MJ, Ramos LM, Tan KE. Retinoblastoma: CT and MRI. Neuroradiology. 1994;36:59–62. doi:10.1007/BF00599199 [CrossRef]
- Shields JA, Shields CL, Honavar SG, Demirci H. Clinical variations and complications of Coats disease in 150 cases: the 2000 Sanford Gifford Memorial Lecture. Am J Ophthalmol. 2001;131:561–571. doi:10.1016/S0002-9394(00)00883-7 [CrossRef]
- Mafee MF, Goldberg MF, Cohen SB, et al. Magnetic resonance imaging versus computed tomography of leukocoric eyes and use of in vitro proton magnetic resonance spectroscopy of retinoblastoma. Ophthalmology. 1989;96:965–975.
- Bhatnagar R, Vine AK. Diffuse infiltrating retinoblastoma. Ophthalmology. 1991;98:1657–1661.
- Galluzzi P, Hadjistilianou T, Cerase A, De Francesco S, Toti P, Venturi C. Is CT still useful in the study protocol of retinoblastoma?Am J Neuroradiol. 2009;30:1760–1765. doi:10.3174/ajnr.A1716 [CrossRef]
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- Lai WW, Edward DP, Weiss RA, Mafee MF, Tso MO. Magnetic resonance imaging findings in a case of advanced Coats’ disease. Ophthalmic Surg Lasers. 1996;27:234–238.
- Edward DP, Mafee MF, Garcia-Valenzuela E, Weiss RA. Coats’ disease and persistent hyperplastic primary vitreous: role of MR imaging and CT. Radiol Clin North Am. 1998;36:1119–1131. doi:10.1016/S0033-8389(05)70235-9 [CrossRef]
- Brisse HJ, Lumbroso L, Fréneaux PC, et al. Sonographic, CT, and MR imaging findings in diffuse infiltrative retinoblastoma: report of two cases with histologic comparison. Am J Neuroradiol. 2001;22:499–504.
- Materin MA, Shields CL, Shields JA, Eagle RC Jr, . Diffuse infiltrating retinoblastoma simulating uveitis in a 7-year-old boy. Arch Ophthalmol. 2000;118:442–443.