Gliomatosis cerebri overview

# Overview
Gliomatosis cerebri is a rare primary brain carcinoma. It is a diffusely infiltrating neuroepithelial tumor, which involves at least three cerebral lobes and occasionally infratentorial structures or the spinal cord. The brain architecture is commonly preserved, with neurons being spared. Gliomatosis cerebri is classified as glial tumors of the central nervous system. Recent data does not classify this tumor growth as a primary diagnosis, instead its name is used to describe a special pattern of diffuse and extensive growth of glioma cells, involving multiple lobes of the brain. Microscopic histopathological examination may reveal diffuse proliferation of immature glial elements resembling astrocytes, oligodendroglia, or undifferentiated cells with cytologic and nuclear atypia, calcifications, microcysts, and mitotic figures without the presence of any necrosis or microvascular proliferation. Gross pathology of gliomatosis cerebri is characterized by a diffuse astrocytic growth pattern involving at least three cerebral lobes and bilateral involvement of the cerebral hemispheres, deep gray matter, brainstem, or cerebellum. Symptoms include: headache, nausea, vomiting, seizure, loss of balance, memory loss, personality changes, cognitive problems, confusion, diplopia, difficulty in swallowing, difficulty in speech, motor weakness, and facial numbness. Imaging through a head CT scan can show an isodense and hypoattenuated mass with ill-defined asymmetry and lack of mass effect. While on brain MRI, gliomatosis cerebri is characterized by bilateral and diffuse infiltrative tumor which is isointense or hypointense on T1-weighted images and hyperintense on T2-weighted and FLAIR images. Other imaging studies for gliomatosis cerebri include MR spectroscopy, MR perfusion, PET scan, and bone scan. Radiotherapy and chemotherapy are recommended among all patients who develop gliomatosis cerebri. Temozolomide and PCV 3 combination chemotherapy are the preferred drugs for the treatment of high-grade and low-grade gliomatosis cerebri, respectively. Supportive therapy for gliomatosis cerebri includes anticonvulsants and corticosteroids. Surgery is not the first-line treatment option for patients with gliomatosis cerebri.

# Historical Perspective
Gliomatosis cerebri was first reported by Landau in 1910. Since then, several physicians published isolated cases of gliomatosis cerebri and only later in 1938, it was completely studied and described by Nevin.

# Classification
Gliomatosis cerebri may be classified into several sub types based on the origin (primary and secondary) and the type of tumor cell (astrocytic, oligodendroglial, and mixed). Recent data does not classify this tumor growth as a primary diagnosis, its name is used to describe a special pattern of diffuse and extensive growth of glioma cells, involving multiple lobes of the brain.

# Pathophysiology
Genes involved in pathogenesis of gliomatosis cerebri include p53, OLIG-2, Ki-67, EGFR, PTEN, VCAM1, VEGF, and gene on chromosomes 7q, 10q, and 13q. Gliomatosis cerebri may be associated with neurofibromatosis type 1 and pilomatricoma. Gliomatosis cerebri is demonstrated by positivity to tumor markers such as GFAP, S-100, and Ki-67.

# Causes
Common causes of gliomatosis cerebri include genetic mutations. The genes associated with the etiology of gliomatosis cerebri include p53,OLIG2, Ki-67, EGFR, PTEN, VCAM1, VEGF, and genes on chromosome 7q, 10q, and 13q. Astrocytic gliomatosis cerebri, which is the most common histologic form of GC demonstrated mutations in p53 and (isocitrate dehydrogenase) IDH1.

# Differentiating brain tumors from other diseases
Gliomatosis cerebri must be differentiated from the following: Progressive multifocal leukoencephalopathy, multiple sclerosis, Marburg disease, multicentric glioblastoma, primary CNS lymphoma, viral encephalitis, acute disseminated encephalomyelitis, CNS vasculitis, Behcet's disease, venous sinus thrombosis, stroke, Gerstmann syndrome, leptomeningeal gliomatosis, Alzheimer's disease, Lewy body dementia, parkinsonism

# Epidemiology and Demographics
Gliomatosis cerebri is a rare brain tumor. The incidence of gliomatosis cerebri is estimated to be around 40 cases per year in the United States. It tends to affect the late teens to middle-aged population, affecting people 15 years old and above. The peak incidence for gliomatosis cerebri is 20-40 years. The median age at diagnosis is 34 years. Males are more commonly affected with gliomatosis cerebri than females. The male to female ratio is approximately 1.5 to 1.

# Risk factors
The most potent risk factor associated with the development of gliomatosis cerebri is neurofibromatosis type 1.

# Screening
There is insufficient evidence to recommend routine screening for gliomatosis cerebri.

# Complications and Prognosis
Without treatment, patients may progress to develop focal neurological deficits, altered mental status, hydrocephalus, brain herniation, and ultimately death. Transformation into glioblastoma (grade 4) usually occurs in the later stages of the disease. Commonly documented complications of gliomatosis cerebri include brain herniation, hydrocephalus, coma, metastasis, recurrence, benign intracranial hypertension, and side effects of radiotherapy and chemotherapy. Prognosis is generally poor with a 5-year survival rate for patients undergoing treatment is approximately 17.7%. Median survival of patients who are treated with whole brain radiotherapy alone is 13.7 months (range 135), whereas those who are treated with combined whole brain radiation therapy and chemotherapy have a median survival of 26.14 months (range 642).

# Staging
There is no established system for the staging of gliomatosis cerebri.

# Symptoms
When evaluating a patient for gliomatosis cerebri, you should take a detailed history of the presenting symptom (onset, duration, and progression), other associated symptoms, and a thorough family and past medical history review. Other specific areas of focus when obtaining the history include review of common associated conditions such as neurofibromatosis type 1. Symptoms of gliomatosis cerebri include: Headache, nausea and vomiting, seizure, loss of balance, memory loss, personality changes, cognitive problems, confusion, diplopia, difficulty in swallowing, difficulty in speech, motor weakness, and facial numbness

# Physical examination
Common physical examination findings of gliomatosis cerebri include dysphagia, dysarthria, nystagmus, papilledema, hemiparesis, facial paresthesia, vision loss, ataxia, mental status changes, aphasia, and focal neurological defects (corticospinal tract defects, spinocerebellar tract defects, and cranioneuropathies).

# Laboratory Findings
There are no diagnostic lab findings associated with gliomatosis cerebri.

# Chest X Ray
Chest x-ray may be performed to detect metastases of gliomatosis cerebri to the lungs.

# CT
Head CT scan is helpful in the diagnosis of gliomatosis cerebri. On head CT scan, gliomatosis cerebri is characterized by an isodense and hypoattenuated mass with ill-defined asymmetry and lack of mass effect.

# MRI
Brain MRI is helpful in the diagnosis of gliomatosis cerebri. On brain MRI, gliomatosis cerebri is characterized by bilateral and diffuse infiltrative tumor which is isointense or hypointense on T1-weighted images and hyperintense on T2-weighted and FLAIR images.

# Ultrasound
There are no ultrasound findings associated with gliomatosis cerebri.

# Other Imaging Findings
Other imaging studies for gliomatosis cerebri include MR spectroscopy (decreased NAA/creatine ratio and elevated choline/creatine ratio, choline/NAA ratio, and myoinositol), MR perfusion (low/normal relative cerebral blood flow), PET scan (markedly decreased accumulation of -fluorodeoxyglucose on F-18 FDG PET, hypermetabolism on C-11 methionine PET, and marked increase in cerebral blood flow on 15(O)-water PET), and bone scan (metastasis to bones).

# Other Diagnostic Studies
Other diagnostic studies for gliomatosis cerebri include biopsy, which demonstrates glial cells resembling astrocytes, oligodendrocytes, or undifferentiated cells with atypia and mitoses.

# Medical Therapy
Radiotherapy and chemotherapy are recommended among all patients who develop gliomatosis cerebri. Temozolomide and PCV 3 combination chemotherapy are the preferred drugs for the treatment of high-grade and low-grade gliomatosis cerebri, respectively. Supportive therapy for gliomatosis cerebri includes anticonvulsants and corticosteroids.

# Surgery
Surgery is not the first-line treatment option for patients with gliomatosis cerebri. CSF shunting is usually reserved for patients with hydrocephalus.

# Primary Prevention
There is no established method for prevention of gliomatosis cerebri.

# Secondary Prevention
There are no secondary preventive measures available for gliomatosis cerebri.