Germinoma U tế bào mầm nội sọ

Intracranial Germinoma • Intracranial germinomas are a type of germ cell tumor, and are predominantly seen in pediatric populations They account for 3-5% of pediatric intracranial tumors but only 0.41% of intracranial tumors in adults • Germinomas are tumors of young patients with a peak incidence of 10-12 years of age (90% of patients being younger than 20 at the time of diagnosis).  • There is a marked male predominance with a M:F of ~13:1 • They are the most common  tumor of the pineal region  • The usual location of intracranial germinoma is in the midline areas such as the pineal and suprasellar regions • Ectopic germinomas, which are tumors arising from offmidline areas, primarily the basal ganglia and thalamus, only constitute 5% to 10% of all intracranial germinomas  •  Other possible sites of involvement are the third ventricle, lateral and fourth ventricles and on occasion, the tumor is widespread at presentation and it is difficult to determine the precise primary site Clinical presentation • Presentation depends on location: • compression of the tectal plate leading to  obstructive hydrocephalus and Parinaud syndrome • involvement of the pituitary infundibulum leads to diabetes insipidus (most common), hypopituitarism (common), optic chiasm compression or signs of intracranial hypertension Radiographic features • Germinomas are soft tissue density, enhancing masses When present in the pineal region they appear to "engulf" the normal pineal tissue and can have associated central calcifcation, in contrast to pineocytomas, and pineoblastomas which are described as "exploding" the foci of calcifcation Cystic components are commonly found in up to 45% of cases Radiographic features • On CT: hyperdensity compared to adjacent brain, enhances brightly • Single calcifed spot may be seen on NECT in early stage • ± cysts • ± hemorrhage (especially in basal ganglia germinomas) • ± hydrocephalus A large lobulated mass is centered on the pineal gland, engulfng the pineal calcifation It is somewhat hyperdense compared to adjacent brain A further smaller mass is seen in the floor of the third ventricle The midbrain is distorted, compressed and demonstrates low density suggestive of edema Obstructive hydrocephalus is present.  MRI MRI demonstrates a soft tissue mass, typically ovoid or lobulated in contour, engulfng the calcifed pineal gland with the following signal characteristics:  • T1: isointense or slightly hyperintense to adjacent brain • T2 – isointense or slightly hyperintense to adjacent brain – may have areas of cyst formation  – may have areas of hemorrhage (low signal) – have a predilection for invading adjacent brain (edema) – central calcifcation appears low signal (engulfed pineal gland) • T1 C+ (Gd): vivid and homogeneous • The vast majority of germinomas demonstrated predominantly restricted (36%) or normal (55%) diffusion A large enhancing mass is centered on the pineal region It is heterogeneous with areas of cystic change There is marked compression of the tectum with resulting obstructive hydrocephalus A little surrounding edema is also present.  There is a T1 isointense to brain, T2 hyperintense mass flling the inferior recesses of the third ventricle and extending down along the infundibulum into the pituitary fossa It demonstrates intermediate relatively homogeneous contrast enhancement The pineal gland, is a little bulky and demonstrates similar signal intensity and enhancement.  The mass elevates and compresses the optic chiasm and results in increased signal in the optic tracts bilaterally The tumor is located in left basal ganglion displaying relative well-defned margin on T2WI The tumor with ill-defned margin is located in right temporal lobe, basal ganglion, internal capsule and thalamus with heterogeneous enhancement on post-contrast T1WI Non-contrast-enhanced CT head at initial presentation.There is transependymal fluid shift with enlargement of the lateral and third ventricles with nodular densities prominent in the occipital and anterior horns bilaterally Post-contrast axial and sagittal MRI sequences with neuronavigation protocol at diagnosis.There is diffuse involvement of the lateral and third ventricles, the suprasellar and pineal regions, and the aqueduct with resultant ventriculomegaly Differential diagnosis • Pineal region mass • pineal cyst (most common benign pineal region mass) • pineal parenchymal tumors (~30% of primary pineal region tumors) – pineocytoma – pineoblastoma • • • • • Pituitary region masses pituitary adenoma craniopharyngioma pituitary lymphoma meningioma Treatment and prognosis • Complete surgical removal does not play a major role in the management of these highly vascular tumors Histological diagnosis following a craniotomy or endoscopic biopsy is recommended for the majority of patients • Radiation alone used in relatively high doses and volumes usually provides a curative option for the majority of patients but the late effects of therapy • The current proposed treatment in a current Children's Oncology Group protocol for CNS germinomas consists of four cycles of chemotherapy followed by lower dose whole ventricular radiation therapy Treatment and prognosis • Overall the prognosis is good, with over 90% 5-year survival with chemotherapy and radiotherapy • Germinomas are potentially malignant in behavior and both infltrate normal brain tissue as well as spread throughout the CNS • https://www.ncbi.nlm.nih.gov/pmc/articles/ PMC5207546/ • https://radiopaedia.org/articles/central-ner vous-system-germinoma • https://link.springer.com/article/10.1007/s0 0381-010-1247-2 • https://www.ncbi.nlm.nih.gov/pmc/articles/ PMC6088312