Tectal plate gliomas are encountered in children and adolescents 4. A male predilection has sometimes been reported although this is by no means certain 3.
An association with neurofibromatosis type I (NF1) has been reported 3-4.
The vast majority of lesions are low grade astrocytoma, although occasionally other glial series tumours are encountered in the tectal region including ependymoma, ganglioglioma and primitive neuroectodermal tumours (PNET) 3.
Typical CT finding is homogeneous expansion of tectal plate, isodense to grey matter with minimal enhancement on postcontrast images 1,3. On CT it is not uncommon to find a central tectal calcification 2-3.
Typically the tumours demonstrate expansion of the tectal plate by a solid nodule of tissue.
- T1: iso to slightly hypointense to grey matter 1-3
- T2: hyperintense to grey matter
- T1 C+ (Gd): usually no enhancement
With time the mass can develop small cystic spaces (sometimes associated with neurological deficits) or calcification 3.
Higher grade tumours tend to be larger and tend to enhance more vividly 3.
Treatment and prognosis
As tectal plate gliomas are low grade and often very slow growing, shunting is often the only required intervention for long term survival. As surgical biopsy can have significant morbidity in this area, usually the diagnosis is made on imaging findings alone.
In the minority of patients who progress, radiotherapy often leads to local control or even tumour regression 2. Surgical excision is sometimes necessary 3.
Imaging predictors of patients who will need further treatment include a size greater than 2.5 cm and presence of contrast enhancement 3.
When the tectum is near-normal then the differential is largely limited to:
- no mass lesion
- a focal stenosis or web may be visible
With larger lesions, where the mass is not definitely arising from the tectal plate then the differential is essentially that of a pineal region mass and therefore includes:
- pineal parenchymal tumours and germ cell tumours
- pineal cyst
- cerebral metastasis
- cavernous malformation
In patients with NF1 a hamartoma should also be considered. They tend to have some T1 hyperintensity 4.
- WHO classification of CNS tumours
- WHO grading of CNS tumours
- VASARI MRI feature set
- diffuse astrocytic tumours
- prognostic markers
- diffuse astrocytoma grading
- low grade astrocytoma
- anaplastic astrocytoma
- glioblastoma variant
- glioblastoma vs cerebral metastasis
- treatment response
- Stupp protocol
- glioma treatment response assessment in clinical trials
- multicentric glioblastoma
- multifocal glioblastoma
- radiation-induced gliomas
- gliomatosis cerebri (growth pattern)
- localised astrocytic tumours
- specific locations
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- 2. Keating RF, Goodrich JT, Packer RJ. Tumors of the pediatric central nervous system. George Thieme Verlag. (2001) ISBN:0865778485. Read it at Google Books - Find it at Amazon
- 3. Poussaint TY, Kowal JR, Barnes PD et-al. Tectal tumors of childhood: clinical and imaging follow-up. AJNR Am J Neuroradiol. 1998;19 (5): 977-83. AJNR Am J Neuroradiol (abstract) - Pubmed citation
- 4. DinçEr A, Yener U, ÖZek MM. Hydrocephalus in patients with neurofibromatosis type 1: MR imaging findings and the outcome of endoscopic third ventriculostomy. AJNR Am J Neuroradiol. 2011;32 (4): 643-6. AJNR Am J Neuroradiol (full text) - doi:10.3174/ajnr.A2357 - Pubmed citation
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