<unk>  is an uncommon WHO Grade IV tumor, which in the vast majority of cases occurs in young children less than two years of age. It most frequently presents as a posterior fossa mass.<unk>  is comprised of rhabdoid tumor cells and varying amounts of small undifferentiated primitive neuroectodermal tumor (PNET)-like, mesenchymally, and/or epithelially differentiated tumor cells. Gene involved in the pathogenesis of<unk><unk>  rhomboid tumor include SMARCB1 (hSNF5/INI-1), a tumor suppressor gene.<unk>  may be associated with rhabdoid predisposition syndrome. On gross pathology,<unk>  is characterized by an encapsulated, grayish, friable mass which is moderately vascular. On microscopic histopathological analysis,<unk>  is characterized by round blue tumor cells of high cellularity composed of<unk>  cells with eccentric nuclei, small nucleoli, and abundant amounts of eosinophilic cytoplasm with frequent mitotic figures.<unk>  is demonstrated by positivity to tumor markers such as epithelial membrane antigen, vimentin, and smooth muscle actin.<unk>  must be differentiated from medulloblastoma, pineoblastoma, spinal primitive neuroectodermal tumors, and other pineal gland masses.<unk>  comprises approximately 1–2% of all pediatric brain tumors; however, in patients less than 3 years of age, this tumor accounts for up to 20% of cases. The incidence of<unk>  is approximately 0.3 per 100,000 individuals in the United States. Males are more commonly affected with<unk>  than females. The male to female ratio is approximately 1.9 to 1. If left untreated, patients with<unk>  may progress to develop obstructive hydrocephalus, leptomeningeal dissemination, and ultimately death. Common complications of<unk>  include obstructive hydrocephalus, leptomeningeal dissemination, and recurrence. Prognosis is generally poor, and the 5-year overall survival rate of patients with<unk>  is 29 ± 9%. Symptoms of<unk>  include headache, vomiting, increased head size in infant, trouble with balance and coordination, and weight loss. Common physical examination findings of<unk>  include papilledema, ataxia, upper motor neuron lesion, and hemiparesis. On MRI,<unk>  is characterized by iso- to slight hyperintensity on T1-weighted imaging and hyperintensity on T2-weighted imaging. There is heterogenous enhancement on contrast administration. The predominant therapy for<unk>  is surgical resection. Adjunctive chemotherapy and radiation is required.
Atypical teratoid rhabdoid tumor
Malignant rhabdoid tumour
Malignant rhabdoid tumor
Endodermal sinus tumor
Ameloblastoma
Primitive neuroectodermal tumor
Pineoblastoma
Esthesioneuroblastoma