Purpose or Case Report: Learn the constellation of typical findings in the tuberous sclerosis complex (TSC). Learn the typical/atypical appearances of these findings. Learn important points to communicate to clinicians regarding these findings.
The tuberous sclerosis complex (TSC) is an autosomal dominant condition that classically presents with cutaneous and neurologic findings such as ash-leaf skin lesions and seizures, respectively. However, clinical presentations can be varied; thus imaging plays an important role in diagnosing TSC, as there is a constellation of radiologic findings that is highly suggestive of TSC.
Multiple organ systems can be involved including cardiac, pulmonary, renal, and neurologic, detailed as follows.
Cardiac rhabdomyomas are seen in 47-67% of TSC cases. They appear as single or multiple masses along the ventricular septum, often detected prenatally and usually regress by age 4, sometimes by birth.
Lymphangioleiomyomatosis (LAM) is seen in 26-49% of TSC cases. LAM involves diffuse cystic changes of the lungs, complicated by recurrent pneumothoraces and chylous effusions. On x-ray, LAM appears as coarse interstitial markings. On CT, the lungs are uniformly involved by thin walled cysts that collapse on expiration.
Renal angiomyolipomas (AML) are seen in 34-80% of TSC cases. AML associated with TSC tend to be bilateral, multiple, larger, and occur at an earlier age than when not associated with TSC. The larger the AML, the higher the risk of aneurysm formation and rupture, a major cause of death in TSC. Thus, for AML larger than 4 cm, prophylactic embolization is recommended. On ultrasound, AML are echogenic and on CT/MR, they are renal masses without calcifications, typically with macroscopic fat although lipid-poor AML also occur.
Common neurologic manifestations include subcortical/cortical tubers, subependymal nodules (SEN), and subependymal giant cell astrocytomas (SEGA). Tubers have different MR appearance in infants compared with older children or adults due to myelination differences. Tubers may demonstrate cystic degeneration or calcifications, and approximately 10% enhance. 88% of SEN are calcified, usually by age 1, and thus can appear as lateral ventricle calcifications on CT. SEN are hyperintense on T1WI with variable enhancement. SEN have the potential to develop into SEGA which typically appear as a slowly enlarging, enhancing nodule greater than 1 cm at the foramen of Monro where it can cause hydrocephalus.
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