Tuberous sclerosis complex diagnosis
● Definitive diagnosis 2 major criteria, or 1 major AND≥ 2 minor
● Possible diagnosis 1 major or ≥ 2 minor
Major criteria
● ≥ 3 hypomelanotic macules ≥ 5mm diameter
● ≥ 3 angiofibromas or fibrous cephalic plaque
● ≥ 2 ungual fibroma
● shagreen patch
● multiple retinal hamartomas
● cortical dysplasias (including tubers & cerebral white matter radial migration lines)
● subependymal nodules
● subependymal giant cell astrocytoma (SEGA)
● cardiac rhabdomyoma
● lymphangioleiomyomatosis
● ≥ 2 angiomyolipomas
Minor criteria
● “confetti” skin lesions
● ≥ 4 pits in dental enamel
● ≥ 2 intraoral fibromas
● achromic retinal patch
● multiple renal cysts
● nonrenal hamartomas
The most common findings are benign tumors in the skin, brain, kidneys, lung, and heart that lead to organ dysfunction as the normal parenchyma is replaced by a variety of cell types 1).
Disease manifestations in different organ systems can vary widely between even closely related individuals and the protean nature of the condition can make clinical diagnosis challenging. TSC was underdiagnosed until the 1980s when individuals with less severe manifestations of the disease began to be recognized. Before the 1980s, incidence rates for TSC were quoted at between 1/100,000 and 1/200,000 2) 3).
Plain skull X-rays
May show calcified cerebral nodules.
CT scan
Intracerebral calcifications are the most common (97% of cases) and characteristic finding. Primarily located subependymally along the lateral walls of the lateral ventricles or near the foramina of Monro.
Low density lesions that do not enhance are seen in 61%. Probably represent heterotopic tissue or defective myelination. Most common in occipital lobe.
Hydrocephalus (HCP) may occur even without obstruction. In the absence of tumor, HCP is usually mild. Moderate HCP usually occurs only in the presence of tumor.
Subependymal nodules are usually calcified, and protrude into the ventricle (“candle guttering” described the appearance on pneumoencephalography).
Paraventricular tumors (mostly giant cell astrocytomas; see pathology (p. 612)) are essentially the only enhancing lesions in TSC.
MRI
Subependymal tubers are high on T2 and low on T1 and only ≈ 10% enhance.
Low signal in subependymal lesions may represent calcification. SEGA enhance intensely (enhancing subependymal lesions are almost always SEGAs).
Radial bands sign: abnormal signal intensity extending in a radial manner, representing cells of varying degrees of neuronal and astrocytic differentiation as well as difficult-to-classify cells.