Multimodal imaging of combined hamartoma of the retina and retinal pigment epithelium.

Abstract

We evaluated the structural and functional features of combined hamartoma of the retina and retinal pigment epithelium using multimodal imaging technologies, including the new technique of optical coherence tomography (OCT) angiography, which has previously not been used to examine this rare condition. Nine eyes of nine Caucasian patients (median age at presentation: 8 years; range: 1−36 years) were evaluated in the Eye Clinic of the University of Naples ‘Federico II’ between September 2014 and February 2015. Patients underwent complete ophthalmic examination, bulbar echography, enhanced depth imaging optical coherence tomography (EDI-OCT), wide-field en-face OCT, multicolour imaging, fluorescein and indocyanine angiography and OCT angiography. The mean best-corrected visual acuity was 20/40 ± 4.2 Snellen. At standardized A-scan echography, the mean tumour basal dimension was 3 mm. All tumours were in the temporal quadrant, and seven affected the left eye. The OCT findings revealed a mean foveal retinal thickness of 522 ± 248 (mean ± standard deviation) μm in affected eyes versus 226 ± 22 μm in unaffected eyes. The mean retinal thickness through the tumour epicentre in affected and unaffected eyes was 809 ± 269 μm and 361 ± 44 μm, respectively. The mean tumour thickness was 752 μm. On EDI-OCT, the mean choroidal thickness below the tumour epicentre was significantly less in affected eyes than the mean choroidal thickness in unaffected eyes (251 ± 50 μm versus 388 ± 38 μm). Both intraretinal and subretinal fluid was present in two affected eyes, intraretinal fluid alone in three affected eyes, retinal striae overlying the tumour in two eyes and retinal schisis in two eyes. Based on multicolour images, hamartomas were classified green or grey, indicating more or less abundant tissue, respectively. En-face OCT revealed an epiretinal membrane and vitreoretinal traction in all patients. Fluorescein and indocyanine angiography in the early phase showed such vascular irregularities as dilation or vascular tortuosity which were not visible in the later phase due to leakage. However, at OCT angiography, vascular irregularities were clearly seen in the tumoral area. Moreover, OCT angiography showed that the main superficial retinal vessels lose most of their collateral branches and present many loops; capillaries were rare and there were anomalies in vessel size. At deep plexus level, changes in vessel size and morphology were evident and the capillary fans were irregular. No functional or anatomic changes versus baseline were identified at the 24-month follow-up observation, except in a 21-year-old man in whom visual acuity decreased. As shown in Fig. 1, multicolour imaging at follow-up in this patient revealed retinal haemorrhage and increased retinal traction. A-scan echography and OCT showed an increase in the size of the tumour base, retinal thickness and retinal traction, which can cause retinal haemorrhage. Optical coherence tomography angiography revealed vessel stretching and a slight reduction in anastomosis. In this patient, the hamartoma slowly increased in size thereby causing shrinkage of the internal membrane of the tumour, which in turn leads to deformation of the retinal vessels as they are attracted towards the centre of the neoplasm (Mele et al. 1984). Surgery in the management of combined hamartoma remains controversial (Bruè et al. 2013). In fact, the surface glial membrane causing the retinal distortion is often an integral part of the tumour, which can mean that is difficult or impossible to strip the membrane and that there is little chance of central vision (Chhablani et al. 2015). In conclusion, our results indicate that the new OCT angiography technique is a non-invasive, reliable method with which to evaluate vascular irregularities in the tumour area without the injection of any dye. Consequently, OCT angiography is an ideal procedure with which to evaluate this condition in young patients.