Introduction: Subependymal giant cell astrocytomas (SEGA) are a common manifestation of TSC. We present the SEGA characteristics in TSC patients included in TOSCA.

Methods: TOSCA is a multicenter, international registry for TSC, conducted at 170 sites across 31 countries worldwide. It includes a core section and six research projects. Clinical characteristics, signs and symptoms, and management of SEGA were evaluated. Information on SEGA size was obtained in a separate research project.

Results: A history of SEGA was reported in 553/2211 patients (25%). Median age at diagnosis was 7 years; 19.2% were diagnosed after age 18 years. SEGA growth since previous scan was reported in 92/463 patients (19.9%; 69/292 [23.6%] aged <18, 23/171 [13.5%] aged ≥18 years). SEGA were asymptomatic in 70.4%. The most common symptoms (>10%) were increased seizure frequency and behavioral disturbance. Main treatment modalities included surgery (59.3%) and mammalian target of rapamycin inhibitors (48.1%). MRIs of 24 patients (6 adults) were analyzed in the SEGA research project. Enlarged ventricles/hydrocephalus in the axial plane were observed in 25%. Mean (range) of maximal diameter of the largest SEGA was 12.3(1-32) x 14.1(2-30) x 14.0(2-34) mm on axial, sagittal, and coronal planes.

Conclusions: In this large group of TOSCA participants, occurrence of SEGA was higher than previously reported. SEGA diagnosis and growth in adults is rare but not excluded, emphasizing the need for continued awareness. Increased seizure frequency and behavioral disturbance were more commonly associated with SEGA growth than symptoms typically associated with increased intracranial pressure.