Hepatitis C virus (HCV) perturbs the host's lipid metabolism and often results in hepatic steatosis. In nonalcoholic fatty liver disease, the intrahepatic down-regulation of phosphatase and tensin homolog deleted on chromosome 10 (PTEN) is a critical mechanism leading to steatosis and its progression toward fibrosis and hepatocellular carcinoma. However, whether an HCV infection triggers the formation of large lipid droplets through PTEN-dependent mechanisms is unknown. We assessed PTEN expression in the livers of patients infected with HCV genotype 1 or 3 with or without steatosis. The role of PTEN in the HCV-induced biogenesis of lipid droplets was further investigated in vitro with hepatoma cells transduced with the HCV core protein of genotype 1b or 3a. Our data indicate that PTEN expression was down-regulated at the posttranscriptional level in steatotic patients infected with genotype 3a. Similarly, the in vitro expression of the HCV genotype 3a core protein (but not 1b), typically leading to the appearance of large lipid droplets, down-regulated PTEN expression by a mechanism involving a microRNA-dependent blockade of PTEN messenger RNA translation. PTEN down-regulation promoted in turn a reduction of insulin receptor substrate 1 (IRS1) expression. Interestingly, either PTEN or IRS1 overexpression prevented the development of large lipid droplets, and this indicates that the down-regulation of both PTEN and IRS1 is required to affect the biogenesis of lipid droplets. However, IRS1 knockdown per se did not alter the morphology of lipid droplets, and this suggests that other PTEN-dependent mechanisms are involved in this process. Conclusion: The down-regulation of PTEN and IRS1 is a critical event leading to the HCV genotype 3a-induced formation of large lipid droplets in hepatocytes. (HEPATOLOGY 2011;54:38-49)

PTEN protein expression is downregulated early in NAFLD, but not in ALD. PTEN immunohistochemical detection could help in the differential diagnosis of NAFLD and ALD.

We present the case of a 52-year-old man with a 2-month history of dyspnea, bilateral pleural effusion and cardiomegaly of rapid onset. A cardiac ultrasound showed pericardial effusion with infiltration of the infero-lateral cardiac wall, right auricle and aortic arch by a mass of unknown origin. Despite 1% blast cells in the peripheral blood, 2 bone marrow biopsies were negative for malignancy. Flow cytometry analysis of the blood and immunohistochemistry study of the pleural liquid showed a blast population of CD34+, CD33+, CD13+ and HLA-DR+ cells; a percutaneous cardiac biopsy showed CD34+ cells in the pericardium which led to the diagnosis of extramedullary acute myeloid leukemia (AML). The patient was treated with induction chemotherapy allowing remission, but unfortunately died of septic shock of fungal origin. This case illustrates a rare presentation of cardiac extramedullary AML.

Denosumab has shown promising results in the management of giant cell tumor of bone, a primary bone tumor with locally aggressive behaviour. We report a case of premature denosumab interruption due to radiological and clinical tumor expansion of a giant cell tumor of the distal ulna. Although denosumab is known to induce tumor regression, with progressive ossification and loss of the characteristic morphology of giant cell tumor of bone, the ulnar tumor specimen showed a moderately to highly cellular proliferation of short spindle-shaped cells, and no osteoclast-like giant cells. There were no abnormal mitotic figures. We considered the surgical specimen as a giant cell tumor of bone with partial regression after prematurely interrupted denosumab treatment. This case illustrates the diagnostic issues of an initially unfavourable evolution raising concern for malignancy, and the difficulties in histological assessment of a partially treated giant cell tumor of bone, that may mimic osteosarcoma.

To the best of our knowledge, this is the first report of an undifferentiated pleomorphic sarcoma arising from a renal graft. Transplantectomy was performed in a 47-year old woman presenting to the emergency room because of general weakness. Preoperative workup revealed a 5.5 cm malignant mass of the graft which was not present on routine ultrasound performed 12 months earlier. Following transplantectomy, local recurrence developed despite complete tumor resection and interruption of immunosuppression. Despite radiation therapy, the outcome was ultimately fatal. Genetic analysis revealed that the tumor had arisen from donor tissue. Annual ultrasound surveillance might not be enough effective to screen for these rare high grade neoplasms.