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At the time of diagnosis, many medical tests are performed. Patients and parents should also be aware of routine testing that needs to be performed. Patients are advised to share the following diagram with their physicians:  Suggested Routine Diagnostic and Surveillance Screening in TSC.

In July 1998 the Tuberous Sclerosis Alliance, then known as the National Tuberous Sclerosis Association, convened a consensus conference of international experts to review the literature and the status of knowledge and research about tuberous sclerosis complex (TSC). The event was funded by the National Institutes of Health, a federal agency dedicated to medical research. One of the consensus panels developed a revised scheme for the TSC diagnostic criteria (see Table 1) based on new information from clinical and molecular genetic studies.

The new diagnostic criteria eliminated any single finding as specifically distinctive or characteristic of the disorder; this represents a change of thought in the diagnostic process.

Originally, cortical tubers were believed to be pathognomonic, or specifically characteristic of TSC. However, evidence now suggests that radiographic brain imaging and histologic studies are unable to distinguish these tubers from isolated cortical dysplasia. Histology is the science of the minute structure of cells, tissues and organs.

Two other types of brain lesions—subependymal giant cell astrocytomas and subependymal nodules—can be distinguished from cortical tubers and from each other, however. In particular, the two subependymal lesions have a histologic and radiographic appearance that differs from the cortical tuber, whereas the giant cell astrocytoma is the only one that tends to enlarge.

It is important to distinguish between the three different brain lesions for identification and monitoring purposes (See Table 1).

An especially important tool in diagnosing TSC is its dermatologic manifestation, which comprises four major and one minor feature of TSC. Hypomelanotic macules are considered a new grouping, whereas the histologically similar forehead plaque, facial angiofibroma, and renal and retinal hamartomas, continue to be considered major features used in diagnosis. Liver, spleen, rectal or other lesions—preferably histologically confirmed hamartomatous lesions—constitute minor features.

As we learn more about TSC and as diagnostic genetic testing becomes more widely available, the diagnostic criteria will again be revised.