Optical Coherence Tomography of Retinoblastoma Shows Origin in Inner Nuclear Layer. Goldfish Tail, Shark Fin, Porpoise Nose Signs.
Carol L. Shields, MD; R. Joel Welch, MD; Raksha Rao, MD; Philip Gordon, BS; Jerry A. Shields, MD
Ocular Oncology Service at Wills Eye Hospital
Introduction: To investigate hand-held optical coherence tomography (HH-OCT) of flat (<1 mm thickness) retinoblastoma.
Methods: Retrospective case series of 20 tumors evaluated with HH-OCT using Optovue iVue.
Results: The mean patient age at examination was 4.1 months (median 4.4, range 0.5-11 months). All tumors were <1 mm thickness. The mean largest tumor basal diameter by HH-OCT was 2.2 mm (median 1.9, range 0.7-4.1 mm) and mean tumor thickness was 468 µm (median 441, range 151-998 µm). By HH-OCT, each retinoblastoma demonstrated epicenter in the inner nuclear layer (INL) in 20/20 (100%) with minute calcification noted in 14 (70%) cases. There were 3 discrete OCT findings included the ‘goldfish tail sign’ where the INL was slightly expanded at the tumor margins (19/20, 95%), the ‘shark fin sign’ where the external limiting membrane (ELM) was pushed into sharp configuration from the mass (15/20, 75%), and ‘porpoise nose sign’ where the tumor herniated and pushed into the outer nuclear layer (ONL) with rounded lateral margins (17/20, 85%). Tumor thickness was correlated with tumor basal dimension yielding a significant linear relationship (height = 0.21 x width, Pearson r=0.89, p<0.001). There was no correlation between tumor size, location, and patient age (all p>0.05). There was no case of subretinal or vitreous seeding.
Discussion: HH-OCT has provided information that suggests retinoblastoma might originate in the inner nuclear layer of the retina.
Conclusion: HH-OCT demonstrated that sub-millimeter retinoblastoma appears to originate from the inner nuclear layer, with typical features of ‘goldfish tail’, ‘shark fin’, and ‘porpoise nose’ signs.|
References: 1. Shields CL, Manalac J, Das C, et al. Review of spectral domain-enhanced depth imaging optical coherence tomography of tumors of the retina and retinal pigment epithelium in children and adults. Indian J Ophthalmol. 2015;63(2):128-32.
2. Rootman DB, Gonzalez E, Mallipatna A, et al. Hand-held high-resolution spectral domain optical coherence tomography in retinoblastoma: clinical and morphological considerations. Br J Ophthalmol. 2013;97(1):59-65.
3. Park K, Soufi K, Shields CL. Clinically invisible retinoblastoma recurrence in an infant. Retina Cases Brief Rep 2017 Feb 28 [Epub ahead of print]