Diffuse astrocytomas, also referred to as low-grade infiltrative astrocytomas, are designated as WHO II tumours of the brain. The term diffuse infiltrating means there is no identifiable border between the tumour and normal brain tissue, even though the borders may appear well-marginated on imaging.

1. CASE STUDY

2. MEDICAL HISTORY
Bệnh nhân nữ – 54 tuổi
Trong vòng 2 năm thỉnh thoảng có cơn ngất
Không đau đầu, không dấu hiệu thần kinh khu trú.
Tiền sử bản thân và gia đình bình thường.

4. CHẨN ĐOÁN
• Theo dõi u thần kinh đệm bậc thấp
• Bệnh nhân được phẫu thuật cắt bỏ khối u và gửi giải phẫu bệnh

5. PATHOLOGY

6. DIFFUSE ASTROCYTOMA

7. BACKGROUND
• Diffuse astrocytomas, also referred to as low-grade infiltrative
astrocytomas, are designated as WHO II tumours of the brain.
• The term diffuse infiltrating means there is no identifiable border between the
tumour and normal brain tissue, even though the borders may appear well-
marginated on imaging.

8. NGUYÊN NHÂN
• Nguyên nhân còn chưa được sáng tỏ tuy nhiên 1 số nghiên cứu cho thấy có sự liên quan
đến sự thay đổi cấu trúc gen ( di truyền, môi trường hoặc cả hai)
• Yếu tối môi trường : tiếp cận ion hoá xạ trị, tiếp xúc với điện từ, chấn thương, virus…
• Lâm sàng có thể khởi phát từ vài tuần, vài tháng đến hàng nằm (u độ ác tính thấp)
• Triệu chứng lâm sàng
• Tăng áp lực nội sọ
• DH thần kinh khu trú
• Động kinh

9. EPIDEMIOLOGY
• Diffuse low-grade gliomas of the cerebral hemispheres are typically diagnosed in
young adults between ages 20-45 years (mean 35 years). There is, in fact, a
biphasic distribution, with one peak in childhood (6-12 years) and the other peak
in early adulthood (26-46 years) 1. Childhood gliomas are mostly diffuse
brainstem gliomas
• There is a slight male predilection (M:F ~1.5) 1.

10. RADIOLOGY
• MRI is the modality of choice for characterising these lesions, and in the case of
smaller tumours, they may be subtle and difficult to see on CT, especially as they
tend not to enhance.

11. CT
• Typically low-grade infiltrating astrocytomas appear as isodense or hypodense regions
of positive mass effect, often without any enhancement (in fact, the presence of
enhancement would suggest higher grade tumours), although gemistocytic
astrocytomas particularly can demonstrate wispy enhancement.
• Calcification is not common (10-20% of cases) 1 and may be related to oligodendroglial
components (i.e oligoastrocytoma).
• Cystic or fluid attenuation components are also encountered, particularly in the
gemistocytic variety.

12. MRI
• T1
• isointense to hypointense compared to white matter
• usually confined to the white matter and causes expansion of the adjacent cortex
• T2/FLAIR
• mass-like hyperintense signal
• high T2 signal is not related to cellularity or cellular atypia, but rather to
oedema, demyelination, and other degenerative change 10
• T1 C+ (Gd)
• no enhancement is often the rule but small ill-defined areas of enhancement are not
rare; however, when enhancement is seen it should be considered as a warning sign
for progression to a higher grade

13. MRI
• DWI/ADC
• typically has facilitated diffusion, with lower ADC values suggesting a higher
grade
• MR spectroscopy
• typically will show elevated choline peak, low NAA peak,
elevated choline:creatine ratio
• elevated myo-inositol and myo-inositol/creatine ratio
• there is lack of the lactate peak seen
• the lactate peak represents the necrosis seen in aggressive mostly WHO grade
IV tumours

19. DIFFERENTIAL DIAGNOSIS
• Infaction: major vascular territory, typical distribution of affected tissue
• Herpes simplex encephalitis : bilateral asymmetrical involvement of the limbic
system, medial temporal lobes, insular cortices and inferolateral frontal lobes.
The basal ganglia are typically spared
• Anaplastic astrocytoma

20. INFACTION
• Major vascular territory
• DWI: Typical distribution of affected tissue

21. INFACTION

22. HERPES SIMPLEX ENCEPHALITIS
• Bilateral asymmetrical involvement of the limbic system, medial temporal lobes,
insular cortices and inferolateral frontal lobes. The basal ganglia are typically
spared
• T1: may show general oedema in the affected region
• T1 C+ (Gd): enhancement occurs later
• T2: hyperintensity of affected white matter and cortex
• DWI/ADC: restricted diffusion

25. TREATMENT AND PROGNOSIS
• Treatment depends on clinical presentation, as well as tumour size and location.
Historically these tumours were managed as follows:
• biopsy to confirm the diagnosis and observe
• surgical resection if feasible
• usually radiotherapy at the time of recurrence or progression
• There is an increasing body of evidence that suggests that chemotherapy +/-
radiotherapy, usually reserved for tumours that progressed to higher grades, may
be of benefit in lower grade tumours also.

26. EM XIN TRÂN TRỌNG CÁM ƠN