الفهرس 
Pathology of malignant hepatic tumourstumoursOnly 14 pages are availabe for public view
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Abstract
Hepatocellular carcinoma (HCC) is the most common primary malignancy of the liver in adults and the third most common cause of cancer death worldwide. The incidence of HCC in the Egypt is rising steadily because of the prevalence of hepatitis C viral infectionand other causes of hepatic cirrhosis. It is currently the fifth most common solid tumor worldwide and the third leading cause of cancer related death.
The primary risk factor for HCC is liver injury from diverse causes that leads to hepatic cirrhosis in most patients. An estimated 78% of HCC cases and 57% of cases of liver cirrhosis are caused by chronic infection with hepatitis B virus (HBV) or hepatitis C virus (HCV).
Bone metastasis from HCC was regarded as an uncommon. This was related to the fact that late metastatic bone lesions from HCC are almost always osteolytic, and this finding is not detected with conventional radiographic techniques until there is considerable loss of density.
PET/CT is superior to PET and CT alone, and/or magnetic resonance imaging (MRI), in the diagnosis and treatment of various primary or metastatic cancers. Thus, PET/CT is a more accurate test than either of its individual components.
PET/CT offers a unique hybrid imaging techniquethat combines the attenuation and morphologic detail of CT with themetabolic information from PET. These images can be fused to allowaccurate co-registration of anatomic and functional data, and thecombination of the two types of images leads to more assured anatomiclocalization of areas of increased metabolic activity.
Accurate anatomic localization of foci of increased metabolicactivity can be difficult or impossible at stand alone PET,particularly in the abdomen and pelvis, which are characterizedby a lack of reliable identifiable anatomic structures and variablephysiological FDG uptake.
Whole body positron emission tomography with (180F-Flurodeoxy-glucose (FDG) in combination with CT scanning (PET/CT) represents one of the most sensitiveimaging modalities for the detection of hepatic metastases and extrahepatic tumor manifestation.
PET/CT is particularly indicated for restaging in patients with suspected recurrent and metastatic disease.
Dual-tracer PET-CT using 11C-ACT and 18F-FDG as radioisotope tracers is an advanced imaging modality for evaluating and staging HCC.
Malignant bone lesionseen at PET-CT is characterized with activity that is greater than 2.5 (SUV>2.5), focal (not diffuse), away from sites of physiological uptake or showing higher uptake than underlying physiological structure as well as morphological disruptions seen at CT of same bone lesion.
So lesionwith activity that is less than that 2.5 (SUV<2.5) and diffuse with benign CT features can confidently be diagnosed as benign bone lesion.
Benign entities like inflammatory lesions and hypermetabolic lesions may also showincreased 18F-FDG uptake giving false positive FDG uptake results so visualization of the bone metastasis is difficultwith stand alone PET.
False negative PET findings can result if bone lesions are non FDG avid. High neighboring background activity can also obscureFDG uptake.
Lesions presenting on PET/CT as sites ofincreased uptake with normal CT findings (showing neither benignnor malignant changes) or presented by malignant CT findings with negative co-registered FDG PET images, can be categorized on PET/CT interpretationas inconclusive.
The main limitations of 18-FDG PET and PET/CT are cost, motion artifact, attenuation correction artifact, CT artifacts and radiation exposure.
Isolated bone metastasis from hepatocellular carcinoma is not necessarily a sign of poor prognosis if there are no other sites of organ metastases.
The finding of any organ metastasis affects management of HCC because it oftenprecludes primary liver tumor resection. However, if patients with isolated bone metastasis are treated as a distinct group that has the potential of longer survival, more rigorous treatment of the primary and secondary (bone) tumor burdens may be considered.