Subependymal nodules and giant cell tumours in tuberous sclerosis complex patients: prevalence on MRI in relation to gene mutation.

Purpose: The purpose of this study was to estimate the association among the presence of subependymal nodules (SENs), subependymal giant cell tumours (SGCTs) and gene mutation in tuberous sclerosis complex (TSC) patients.
Methods: Clinical records and images of 81 TSC patients were retrospectively reviewed by two neuroradiologists in consensus. All patients were assessed for gene mutations and were categorized as TSC1 or TSC2 mutation carriers, or no-mutations-identified (NMI) patients. They underwent a brain magnetic resonance imaging (MRI) using 0.1 mmol/kg of gadobutrol. Any enhancing SEN ≥ 1 cm and placed near the foramen of Monro was considered SGCT. Two MRI follow-up exams for each patient with SGCT were evaluated to assess tumour growth using Wilcoxon and chi-squared tests.
Results: Of 81 patients, 44 (54%) were TSC2 mutation carriers, 20 (25%) TSC1 and 17 (21%) NMI. Nine (11%) had a unilateral and three (4%) a bilateral SGCT. Fifty of 81 patients (62%) showed at least one SEN. None of the 31 patients without SEN showed SGCTs, whilst 12 (24%) of the 50 patients with at least one SEN showed SGCTs (p = 0.003). The association between the presence of SGCT or SEN and gene mutation was not significant (p = 0.251 and p = 0.187, respectively). At follow-up, the median SGCT diameter increased from 14 to 15 mm (p = 0.017), whilst the median SGCT volume increased from 589 to 791 mm(3) (p = 0.006).
Conclusions: TSC patients with SENs are more likely to present with SGCT than those without SENs, in particular for TSC2 mutation carriers. The SGCT growth rate may be missed if based on the diameter instead of on the volume.