[Pathology along the liver sinusoids: endothelial and perisinusoidal findings]

Anatomic and Clinical Pathology Characterization of Drug-Induced Sinusoidal Obstruction Syndrome (Veno-Occlusive Disease) in Cynomolgus Macaques

Sinusoidal obstruction syndrome (SOS) is a unique form of liver injury that occurs after exposure to chemotherapeutic drugs and toxins. The diagnosis of SOS in humans remains a challenge as the clinical criteria have low specificity and there are no reliable noninvasive biomarkers. The mechanism of injury is believed to be damage to liver endothelial cells, primarily sinusoidal endothelial cells (SECs), which leads to sinusoidal dilation, central venous fibrosis, and/or nodular regeneration. Nonclinical data suggest that this uncommon liver toxicity can be recapitulated in cynomolgus monkeys, and it is critical that pathologists are familiar with its characteristic clinicopathologic features. Elevations in liver enzymes, in particular aspartate aminotransferase, associated with isolated thrombocytopenia, should raise the suspicion of SEC injury for specific drug classes. Characterization of liver microscopic findings in monkeys benefits from the use of appropriate stains, such as reticulin stain, and VEGFR2 and CD34 immunohistochemical (IHC) stains. CD41 IHC demonstrates platelet accumulation in injured sinusoids, the likely cause of thrombocytopenia commonly reported in SOS. In conclusion, this report provides a comprehensive characterization of the pathology findings of drug-induced SOS in monkeys with the objectives of ensuring appropriate nonclinical recognition of the liability and informing clinical development strategy and monitoring.

AMACR is not applicable as a diagnostic tool in hepatocellular carcinoma

Alpha-methylacyl coenzyme A racemase (AMACR or P504S) is a mitochondrial and peroxisomal protein present in a variety of human cells. Demonstration of increased expression is used diagnostically in prostatic adenocarcinoma. AMACR is also produced by normal hepatocytes and it has been postulated that the demonstration of AMACR expression or its pattern of distribution is useful in the diagnosis of hepatocellular carcinoma (HCC) (Jiang et al., Hum Pathol 2003;34, Guzman et al., Appl Immunohistochem Mol Morphol 2006;14, Li et al., J Exp Clin Cancer Res 2008;27). The aim of the present study was to evaluate whether immunohistochemical staining for AMACR can be used in a routine histopathologic setting. Immunohistochemical staining for AMACR was performed on paraffin-embedded tissue from livers resected for HCC during 1980-2006 at Rigshospitalet, Copenhagen, Denmark (n = 44). Tumor sections as well as surrounding non-neoplastic tissues were studied. In both tumor and non-tumor tissues, intracellular localization and staining pattern were assessed and the staining intensity of AMACR was graded. The fraction of stained tumor cells was not significantly different from that of stained non-tumor cells in the same patients (p = 0.97). A significantly lower staining intensity was observed in clear cell areas (p = 0.005), but the AMACR expression did not correlate with the HCC type and could not distinguish neoplastic from non-neoplastic liver cells. AMACR is not applicable as a tool in the histopathologic diagnosis of HCC.