Teaching Case

A 25-year-old man with no previous medical history was admitted to the neurology department due to an increased intracranial pressure. An achromic cutaneous spot on the thigh and facial brownish papules were noted on the patient as well as the patient’s father (Fig. 1). However, the funduscopic examination was normal.

Cranial MRI showed a tumour located in the right frontal horn of the lateral ventricle, near the foramen of Monro. This tumour was large (35 x33 x26 mm), and had a mixed signal: solid with patchy enhancement, and cystic with ring enhancement. (Fig. 2)
Axial T2 weighted images showed multiple cortical tubers (Fig. 3), white matter abnormalities, and cystic subependymal nodule of right lateral ventricle (Fig. 4)

Thoraco-abdominal computed tomography (CT) was normal.

As described by Bourneville in 1880 [1], tuberous sclerosis is a hereditary disease of dominant autosomic transmission, characterized by high and incomplete penetrance [2]. The main feature of this hamartomas is the excessive proliferation of one or several tissues, which explains the multisystemic attack.

The most frequent clinical manifestations are:
- Typical cutaneous lesions: observed in 70 to 80% of the cases [3], including: hypomelanotic macules present at birth, Facial angiofibromas symmetrically distributed at the middle of the face, peri-ungual and ungual fibromas (Köenen tumours) flesh-coloured and usually multiple.
- Neurological manifestations: the first cause of morbi-mortality [4], including epilepsy, mental deficiency, flexion spasm and increased intracranial pressure.

MRI allows exhaustive assessment of brain lesions that are represented by:
Cortical tubers: the first cause of neurological manifestations. It is present in 95% [5] of cases, and involves the cortical and subcortical white matter. In CT, it appears as non-enhancing peripheral triangular lesion. MR imaging clearly demonstrates cortical and white matter lesions: areas of increased signal intensity on T2 weighted and FLAIR in the cortical and subcortical regions. Tubers rarely exhibit contrast enhancement.
Subependymal nodules: found in 95% of cases [5], generally located at the surface of the lateral ventricles, and more rarely the third/fourth ventricle or Sylvius’s aqueduct. It has similar signal intensity to white matter and shows enhancement in 30 % of lesions [6].

Subependymal giant cell astrocytomas: present in 6 - 14 % of patients [7]. They are histologically benign but sometimes locally invasive. The hole of Monro is the preferential site which is often responsible for hydrocephalus. MR imaging shows low signal intensity on T1, high signal on T2 with patchy enhancement.

White matter abnormalities: Secondary to an abnormal myelinisation. MR imaging reveals linear bands iso to low signal intensity on T1 and high signal on T2.

Note that even in symptomatic patients (seizures); the cerebral imaging can be normal in 5% of the cases [3].
Extracranial signs must be searched for: kidney angiomyolipomas, retinal Hamartomas, cardiac rhabdomyomas, pulmonary lymphangiomyomatosis.

In 2012, diagnostic criteria of tuberous sclerosis of Bourneville was updated with clarification of clinical criteria and addition of the possibility of a genetic diagnosis. [8]
Treatment can improve the quality of life of patients: anticonvulsant medication for seizures, and surgical resection of compressive tumours [8].The prognosis depends on several factors: the number of subependymal nodules, cortical tubers and the presence of infantile spasms. Screening must be systematic in the patient’s parents and siblings.