The term<unk>  most often refers to a tumor in the brain that has a histology identical to two other tumors: dysgerminoma in the ovary and seminoma in the testis. It may be benign or malignant. Germ cell tumors (GCTs) are classified as extragonadal if there is no evidence of a primary tumor in either the ovaries or the testes. Extragonadal GCTs typically arise in midline locations, and specific sites vary with age of the patient. In infants and young children, intracranial GCTs and sacrococcygeal teratomas are more common than other locations. In adults, the most common sites are the anterior retroperitoneum, mediastinum, and the pineal and suprasellar regions. Intracranial germ cell tumors are a heterogeneous group of lesions which occur in children and adults.<unk>  may be classified according to World Health Organization into two groups:<unk> s and nongerminomatous germ cell tumors. Based on the tumor markers secreted into the cerebrospinal fluid (CSF) and serum, as well as by the presence of histochemical markers on tumor cells, intracranial germ cell tumors may be classified into either secreting  or non secreting tumors. Based on the prognosis of the tumor, intracranial germ cell tumors may be classified into either good, intermediate, or poor prognosis. On gross pathology, smooth and bosselated external surface, and soft, fleshy and either cream-colored, gray, pink or tan interior are characteristic findings of<unk> .
On microscopic histopathological analysis, uniform cells that resemble primordial germ cells, consisting of large, round cells with vesicular nuclei and clear or finely granular cytoplasm that is eosinophilic are characteristic findings of<unk> . Genes involved in the pathogenesis of<unk>  include gains of 1p, 8p, and 12q and losses of 13q and 18q, duplication of the short arm of chromosome 12, loss of 1p and 6q, alterations in sex chromosomes in children, alterations of the p14 gene, mutations of the c-kit gene, aberrations of CCND2 (12P13), and RB1, and gain-of-function mutations of KIT. The progression to<unk>  usually involves the mutations of the KIT/RAS signalling or AKT1/mtor pathways and cyclin/CDK-RB-E2F pathway if CCND2 (12P13) and RB1 genes are aberrated.
The peak of<unk>  occurs at ages 15-19 years: the median age at diagnosis is 10-12 years. CNS germ cell tumors commonly affects individuals between birth and 34 years of age. Males are more commonly affected with pineal<unk>  than females. The male to female ratio is approximately 5-22 to 1. Females are more commonly affected with suprasellar<unk>  than males. The female to male ratio is approximately 1.3:1. Symptoms of<unk>  include headache, vomiting, papilledema, lethargy, somnolence, ataxia, behavioral changes, decline in academic performance, paralysis of upward gaze, paralysis of convergence, diabetes insipidus, delayed pubertal development, precocious puberty, isolated growth hormone deficiency, hypopituitarism (central hypothyroidism, adrenal insufficiency), decreased visual acuity from chiasmal or optic nerve compression, and visual field deficit (e.g, bitemporal hemianopsia). Presenting symptoms of patients with intracranial GCTs depend upon the location, size of the tumor, and the patient's age. MRI of the brain and spine with and without gadolinium is the imaging modality of choice for<unk> . On MRI, intracranial GCTs appear isointense or hypointense on T1 sequences and hyperintense on T2 sequences. The predominant therapy for CNS germ cell tumors is radiation therapy. Adjunctive chemotherapy and surgery may be required. The feasibility of surgery depends on the type of the intracranial germ cell tumor at diagnosis. Surgery is not the first-line treatment option for patients with germ cell tumors. Surgery is usually reserved for patients with either NGGCTs, or in patients who have had an incomplete response to initial chemotherapy, and in patients with "growing teratoma syndrome".
Germinoma
Pineal germinoma
Medulloblastoma
Chordoma
Neuroma
Brown tumor
Gonadoblastoma
Ameloblastoma