Cytokeratin immunohistochemical examination of liver biopsies in infants with Alagille syndrome and biliary atresia.

Identifying bile duct epithelium is sometimes difficult with standard histologic techniques. The availability of antibodies to specific cytokeratin (CK) intermediate filaments has allowed identification of CK expressed by bile duct epithelium. Formalin-fixed, paraffin-embedded liver tissue from five infants (aged 1-12 months) with Alagille syndrome and five infants with biliary atresia (aged 1.5-11 months) were pepsin digested then reacted with a combination of anti-cytokeratin monoclonal antibodies using an avidin-biotin immunoperoxidase technique. Liver tissue obtained at autopsy from infants without primary liver disease (aged 22 weeks gestation to 24 months) was treated similarly for comparison. Control specimens showed progression from prominent immunoreactivity of the ductal plate cells at the rim of the portal tract (22-24 weeks gestation) to incorporation of tubular ductal structures into portal tract mesenchymal tissue (26-34 weeks gestation) and formation of intensely immunoreactive mature discrete interlobular ducts with progressive loss of cytokeratin immunoreactivity of the ductal plate cells (1-24 months). In contrast, biopsies from infants with Alagille syndrome showed few immunoreactive interlobular ducts. Biopsies from infants with Alagille syndrome less than 2 months old showed only immunoreactivity of single ductal plate cells or small ductules at the periphery of the portal tracts. Biopsies from some infants greater than 3 months old showed increased numbers of immunoreactive cells in groups and anastomosing bands lacking true lumens and extending into the fibrous bridges between adjacent portal areas (neoductular proliferation).(ABSTRACT TRUNCATED AT 250 WORDS)

Hypointense renal cell carcinoma: MR imaging with pathologic correlation.

In two pathologically documented cases of renal cell carcinoma, the appearance of the tumors at magnetic resonance (MR) imaging was markedly hypointense relative to normal renal parenchyma on both T1- and T2-weighted spin-echo images. Pathologic examination of both tumors revealed diffuse iron scattered throughout the tumors. The paramagnetic effect of the iron may account for this unusual hypointense appearance at spin-echo imaging, independent of pulse sequence.

Lidocaine metabolite and creatinine measurements in the Ektachem 700: steps to minimize its impact on patient care.

The single-slide method used for creatinine in the Kodak "Ektachem" analyzer is far more precise than the two-slide method. We confirm that sera from patients on intravenous therapy with lidocaine exhibit a positive bias in results for creatinine but that lidocaine itself does not interfere. Instead, N-ethylglycine, a metabolite of lidocaine with a structure similar to that of sarcosine, is probably the cause. A method that allows N-ethyglycine to be measured directly is described. We followed the degree of this interference through five generations of the slide. Our investigations include two detailed comparison studies between the Kodak Ektachem 700 and the Beckman Astra analyzers. Creatinine determinations on lidocaine-treated patients when first-generation slides were used averaged 4.6 mg/L higher than determinations on these same specimens performed in the Astra. Serum creatinine results from patients not on lidocaine showed no significant difference between the two instruments. The average difference in generation 2, 3, and 4 slides was 0.24, 0.22, and 2.5 mg/L, respectively. No more than 2% of our creatinine results had a clinically significant lidocaine-related bias. We show how to identify and correct this small proportion of results that are biased because of lidocaine therapy.