Histologic features in autoimmune hepatitis

In order to see if the term of "plasma cell hepatitis", dating back to the early sixties, is still valid as a morphological diagnosis for autoimmune chronic hepatitis (AICH), and to find out if the existence of several subgroups is reflected by histopathology, we investigated 26 patients with chronic hepatitis, who met the criteria of autoimmune hepatitis based on tests for antinuclear, anti-smooth muscle antibodies (SMA) and on immunoassays for liver-kidney-microsomal (LKM) antigen, liver membrane antigen (LMA), and soluble liver antigen (SLA). In our material autoimmune hepatitis represent the entire spectrum of chronic hepatitis with variable inflammatory activity ranging from chronic persistent hepatitis to severe inflammatory lesions in chronic active hepatitis with transition to cirrhosis. When compared to viral chronic hepatitis A and non-A, non-B, however, characteristic features can be evaluated consisting in broad hypocellular areas of collapse and microacinar transformation of hepatocytes with hydropic swelling being the predominant type of cell lesion. Eosinophilic clumping and acidophilic necrosis were insignificant. Plasma cells were not a constituent feature of AICH. From this histopathologic pattern it may be concluded that the disease seems to run a sluggish course in most patients, however, in few cases a dramatic development may determine the disease with fatal acute episodes which are terminated by death or fade into slow progression. The different subgroups could not be distinguished by histopathology.(ABSTRACT TRUNCATED AT 250 WORDS)     

Deposition of keinoid fibers in gastrointestinal stromal tumors of the small intestine. Report of two cases and review of the literature

Skeinoid fibers are interstitial collections of a pathological collagen, most often seen in gastrointestinal stromal tumors. They were first described in 1991. We report two cases of intestinal stromal tumors, one in an exceptionally young patient with excessive skeinoid fiber deposition. The microscopic as well as the ultrastructural findings of skeinoid fibers are demonstrated and their role is discussed considering the newest literature.     

Klarzelltumor der Lunge

Clear cell tumors of the lung are rare tumors composed of epithelioid HMB45 positive tumor cells. It has been proposed that clear cell tumors generate from perivascular epithelioid cells which are also found in renal angiomyolipoma. Due to its morphologic epithelioid features with clear cytoplasm the distinction from either primary or metastatic clear cell carcinoma is difficult. Usually clinical investigations do not lead to the final diagnosis so that only subsequent histological examination and immunophenotyping can establish the correct tumor classification. We describe the case of a 52 year old woman who underwent exploratory thoracotomy because of a lung mass in the right lower lobe. In frozen sections a solid trabecular tumor was diagnosed, paraffin histology and immunohistochemistry revealed a clear cell tumor of the lung. The difficulty of the correct diagnosis of the clear cell tumor of the lung in frozen sections is discussed as well as the differential diagnosis.     

Gene conversion is a likely cause of mutation in PKD1

Approximately 70% of the gene responsible for the most common form of autosomal dominant polycystic kidney disease ( PKD1 ) is replicated in several highly homologous copies located more proximally on chromosome 16. We recently have described a novel technique for mutation detection in the duplicated region of PKD1 that circumvents the difficulties posed by these homologs. We have used this method to identify two patients with a nearly identical cluster of base pair substitutions in exon 23. Since pseudogenes are known to be reservoirs for mutation via gene conversion events for a number of other diseases, we decided to test whether these sequence differences in PKD1 could have arisen as a result of this mechanism. Using changes in restriction digest patterns, we were able to show that these sequence substitutions are also present in N23HA, a rodent-human somatic cell hybrid that contains only the PKD1 homologs. Moreover, these changes were also detected in total DNA from several affected and unaffected individuals that did not harbor this mutation in their PKD1 gene copy. This is the first example of gene conversion in PKD1 , and our findings highlight the importance of using gene-specific reagents in defining PKD1 mutations.