Retinal Astrocytic Hamartoma Arises in Nerve Fiber Layer and Shows "Moth-Eaten" Optically Empty Spaces on Optical Coherence Tomography

Abstract

Purpose: To evaluate the specific spectral-domain (SD) optical coherence tomography (OCT) features of retinal astrocytic hamartoma (RAH) and the relationship of these features with tumor size and location.

Design: Retrospective case series.

Participants: Forty-seven eyes of 42 patients with RAH.

Methods: All patients with clinically confirmed RAH were imaged with fundus photography and SD OCT.

Main outcome measures: Precise OCT location of RAH features and the relationship of patient age, visual acuity, tumor size, and tumor location to the presence and size of intralesional optically empty spaces (OESs), appearing as so-called moth-eaten spaces.

Results: Of 42 patients with RAH, 36 (86%) had unilateral disease and 6 (14%) had bilateral disease. Systemic tuberous sclerosis complex was present in 8 patients (19%). The largest tumor (per eye) demonstrated a mean basal diameter of 3.0 mm (median, 2.0 mm) and a mean thickness of 1.9 mm (median, 1.8 mm). The mean tumor proximity to the foveola was 3.0 mm and that to the optic disc was 1.8 mm. Related features included subretinal fluid (n = 9; 19%), cystoid retinal edema (n = 6; 13%), retinal traction (n = 11; 23%), intralesional cavities (n = 28; 60%), and intralesional calcification (n = 29; 62%). On SD OCT, the tumor epicenter was in the nerve fiber layer (n = 47; 100%), with all other retinal layers appearing thinned or compressed. The tumor showed OESs (n = 43; 91%), representing intralesional calcification or cavitation, and each OES showed a mean diameter of 327 μm (median, 200 μm). When comparing the number of OESs per SD OCT cut through the mass, we found no relationship with patient age, tumor diameter and thickness, distance to the foveola or optic disc, tumor calcification, central macular thickness, or logarithm of the minimum angle of resolution (logMAR) visual acuity. However, a correlation of OES number with OES size (P = 0.01) and macular tumor location (P = 0.03) was found. Further analysis demonstrated OES size correlated with tumor basal diameter (P < 0.01), tumor thickness (P < 0.01), tumor calcification (P = 0.01), and logMAR visual acuity (P = 0.02).

Conclusions: Retinal astrocytic hamartomas arose in the nerve fiber layer in every case and demonstrated moth-eaten OES, related to intrinsic calcification or cavitation, in 91% of cases. Macular tumors have a greater number of OESs, whereas larger calcified tumors have larger OES diameter.