Primitive neuroectodermal tumor is a malignant (cancerous) neural crest tumor. It is a rare tumor, usually occurring in children and young adults under 25 years of age. The overall 5 year survival rate is about 53%.It gets its name because the majority of the cells in the tumor are derived from neuroectoderm, but have not developed and differentiated in the way a normal neuron would, and so the cells appear "primitive".PNET belongs to the Ewing family of tumors. Genetics
Using gene transfer of SV40 large T-antigen in neuronal precursor cells of rats, a brain tumor model was established. The PNETs were histologically indistinguishable from the human counterparts and have been used to identify new genes involved in human brain tumor carcinogenesis. The model was used to confirm p53 as one of the genes involved in human medulloblastomas, but since only about 10% of the human tumors showed mutations in that gene, the model can be used to identify the other binding partners of SV40 Large T- antigen, other than p53. Diagnosis
Classification
It is classified into two types, based on location in the body: peripheral PNET and CNS PNET. Peripheral PNET
The peripheral PNET (pPNET) is now thought to be virtually identical to Ewing sarcoma:
"Current evidence indicates that both Ewings sarcoma and PNET have a similar neural phenotype and, because they share an identical chromosome translocation, they should be viewed as the same tumor, differing only in their degree of neural differentiation.
Congestive hepatopathy, is liver dysfunction due to venous congestion, usually due to congestive heart failure. The gross pathological appearance of a liver affected by chronic passive congestion is "speckled" like a grated nutmeg kernel; the dark spots represent the dilated and congested hepatic venules and small hepatic veins. The paler areas are unaffected surrounding liver tissue. When severe and longstanding, hepatic congestion can lead to fibrosis; if congestion is due to right heart failure, it is called cardiac cirrhosis. Signs and symptoms
Signs and symptoms depend largely upon the primary lesions giving rise to the condition. In addition to the heart or lung symptoms, there will be a sense of fullness and tenderness in the right hypochondriac region. Gastrointestinal catarrh is usually present, and vomiting of blood may occur. There is usually more or less jaundice. Owing to portal obstruction, ascites occurs, followed later by generalised oedema. The stools are light or clay-colored, and the urine is colored by bile. On palpation, the liver is found enlarged and tender, sometimes extending several inches below the costal margin of the ribs. Pathophysiology
Increased pressure in the sublobular branches of the hepatic veins causes an engorgement of venous blood, and is most frequently due to chronic cardiac lesions, especially those affecting the right heart (e.g., right-sided heart failure), the blood being dammed back in the inferior vena cava and hepatic veins. Central regions of the hepatic lobules are red–brown and stand out against the non-congested, tan-coloured liver.