CLINICALLY INVISIBLE RETINOBLASTOMA RECURRENCE IN AN INFANT Krystal Park, BS, Kareem Sioufi, MD, Carol L. Shields, MD Purpose: To report a case of clinically invisible retinoblastoma recurrence detected only on spectral-domain optical coherence tomography. Methods: Case report. Results: A 3-week-old girl with bilateral familial retinoblastoma underwent six cycles of intravenous chemoreduction. Both eyes showed tumor regression. After 6 cycles of chemoreduction, the tumor in the right eye appeared with clinical regression; however, by spectral-domain optical coherence tomography, there was 40 mm increase in thickness and 290 mm increase in basal diameter. Due to tumor proximity of 1.85 mm to the foveola, the recurrence was treated via intraarterial chemotherapy with two cycles of Melphalan 3 mg. After treatment, spectral-domain optical coherence tomography showed complete regression of the recurrent tumor to a flat scar with intact fovea. Conclusion: Precise submillimeter imaging with spectral-domain optical coherence tomography for monitoring retinoblastoma is important and can allow detection of early recurrences that might be clinically invisible otherwise, as well as surveillance of the fovea. RETINAL CASES & BRIEF REPORTS 0:1–3, 2017 From the Ocular Oncology Service, Wills Eye Hospital, Thomas Jefferson University, Philadelphia, Pennsylvania. R etinoblastoma typically presents with leukocoria, most often detected by parents and confirmed by the ophthalmologist as a solid retinal mass on indirect ophthalmoscopy. 1,2 Using ophthalmoscopy, tumors as small as 100 mm to 200 mm are often transparent but can sometimes be identified. 2 However, newer technology has allowed retinoblastoma detection even when the tumor is clinically invisible, using spectral-domain optical coherence tomography (SD-OCT). 3,4 Herein, we describe SD-OCT for detection of clinically invisible retinoblastoma recurrence. Case Report A 3-week-old girl with bilateral familial retinoblastoma, classified as Group B in each eye (both eyes), was treated with intravenous chemoreduction for six cycles, achieving tumor control OU (Figure 1, A and B). One month after completion of chemoreduction (Figure 1, C and D), the macular tumor in the right eye appeared stable clinically, but SD-OCT detected increase in thickness by 40 mm and enlargement in base by 290 mm, suggestive of early subclinical recurrence. This tumor was located 1.85 mm from the foveola. To protect the foveola from tumor invasion, low-dose intraarterial chemotherapy (IAC) with Melphalan 3 mg was provided (two cycles) and tumor regression (Figure 1, E and F) with foveal preservation was achieved and documented on SD-OCT. Discussion New technology, such as SD-OCT, is routinely used in our management of retinoblastoma, to monitor foveal anatomy and to identify new or recurrent clinically invisible tumors. 4,5 This allows for detection of tiny retinoblastomas that might otherwise evade ophthalmo- scopic detection, typically those ,100 mm in basal dimension. 2 The use of SD-OCT also allows for precise monitoring of tumor response after therapy, especially tumors encroaching the perifoveal region. 5 Supported by the Eye Tumor Research Foundation, Philadel- phia, PA (C.L.S.). The funders had no role in the design or conduct of the study, in the collection, analysis and interpretation of the data, and in the preparation, review, or approval of the manuscript. None of the authors has any conflicting interests to disclose. C. L. Shields had full access to all the data in the study and takes responsibility for the integrity of the data and accuracy of the data analysis. Reprint requests: Carol L. Shields, MD, Ocular Oncology Service, Wills Eye Hospital, 840 Walnut Street, Suite 1440, Philadelphia, PA 19107; e-mail: carolshields@gmail.com 1 Copyright ª by Ophthalmic Communications Society, Inc. Unauthorized reproduction of this article is prohibited.