Metanephric adenoma: histology, immunophenotype, cytogenetics, ultrastructure

Metanephric adenoma is a rare renal neoplasm that is histologically and clinically unique. We found this neoplasm in a 54-year-old woman. This large, well-circumscribed, solid, tan tumor showed histologic similarity to developing metanephric tubular epithelium. It is composed of uniformly small epithelial cells forming tubules. Immunohistochemical evaluation showed that the tumor cells express proximal tubule marker URO-2 and wt1 gene protein product, commonly expressed in Wilms' tumors. Ultrastructurally, the epithelial cells were characterized by the presence of cilia on the luminal side and were resting on an abundant basement membrane. Cytogenetic analysis showed normal female karyotype. The unique features of metanephric adenoma should be clinically and pathologically recognized because of its invariably benign course.

The radiologic and pathologic spectrum of biliary hamartomas

OBJECTIVE

The purpose of our study was to correlate the spectrum of radiologic and pathologic findings in a series of patients with biliary hamartomas and known extrahepatic malignancy.

MATERIALS AND METHODS

Biliary hamartomas were diagnosed in 18 patients with a primary malignant lesion who had liver biopsy for evaluation of possible metastatic disease. Prebiopsy imaging studies included CT in 16 patients and sonography in 11. Imaging studies were reviewed retrospectively and correlated with findings at surgery and on pathologic examination. The hamartomas were classified histologically by the degree of cystic dilatation of bile ducts within the lesion.

RESULTS

Radiologically, biliary hamartomas presented a spectrum of findings including one or two circumscribed lesions (5-10 mm in diameter) in four patients; multiple (about five) lesions (approximately 5 mm each) in one patient; innumerable tiny, nearly uniform (2-5 mm) lesions in two patients; and innumerable lesions of varying size (2-15 mm) in three patients. Among the patients with innumerable lesions, the nodules were either uniformly or nonuniformly distributed throughout the liver. In all cases, the lesions were hypodense on contrast-enhanced CT scans and hypoechoic on sonograms. In eight patients, the lesions were not visible by imaging but biopsies were done at surgery when single or multiple tiny nodules were noted on the liver surface. The diagnosis was made by either wedge or core-needle biopsy; fine-needle aspirations were nondiagnostic. Pathologic examination revealed single or multiple hamartomas of varying sizes ranging from solid to largely cystic lesions; the degree of cystic dilatation did not correlate with imaging findings. Visibility on imaging correlated with larger lesion size; small surface lesions were usually occult.

CONCLUSION

Biliary hamartomas cause single or multiple nonspecific hepatic lesions that may mimic metastases. This diagnosis should be considered in patients with a primary malignant tumor when single or multiple small hepatic lesions are seen, regardless of uniformity of size or distribution.

The EWS gene, involved in Ewing family of tumors, malignant melanoma of soft parts and desmoplastic small round cell tumors, codes for an RNA binding protein with novel regulatory domains

The EWS gene, which maps to band q12 of human chromosome 22, is involved in a wide variety of human solid tumors including Ewing sarcoma, related primitive neuroectodermal tumors, malignant melanoma of soft parts and desmoplastic small round cell tumors. In these tumors, the EWS is fused to genes encoding transcriptional activators/repressors, like Fli-1 or erg or ATF 1 or wt1. To better understand the function of the EWS protein, we cloned the EWS cDNA. Sequence analysis of this cDNA revealed differential splicing involving two exons encoding 72 amino acids. Both alternatively spliced transcripts, EWS and EWS-b, are expressed in a variety of cells. Because EWS proteins contain putative conserved RNA binding motifs, we studied the RNA binding properties of the EWS protein. The EWS-b protein binds to RNA in vitro and, specifically, to poly G and poly U. The RNA binding activity was localized to the carboxy terminal 86 amino acids, which constitute RGG box. Thus the amino terminal domain of EWS (NTD-EWS), which is involved in chromosome translocation may regulate the specificity of RNA binding activity of EWS. An EWS-erg chimeric protein, which is found in Ewing's sarcoma cells, functions as a transcriptional activator. Mutational analysis of EWS-erg chimeric protein revealed that NTD-EWS functions as a regulatory domain for the transcriptional activation properties of EWS-erg chimeric protein.

Angiomyolipoma of the nasal cavity: case report and review of the literature

An unusual localization of intranasal angiomyolipoma is described in an adult male patient with no signs of tuberous sclerosis. The lesion was composed of mature fat cells, vascular spaces with lack of elastic tissue, and presence of bundles of mature smooth muscle cells. Antibodies to intermediate filaments revealed presence of vimentin and absence of desmin in both smooth muscle bundles and in vessel walls. A review of the literature has shown that this is only the third reported case of the angiomyolipoma of the nasal cavity, and some important differences between this entity and renal angiomyolipoma are described.

Renal cell carcinoma in the presence of adult polycystic kidney disease

A case of autosomal dominant polycystic kidney disease associated with widely metastatic renal cell carcinoma is reported. The patient had presented with pneumothorax, weight loss, leukocytosis, lytic bone lesions, and hypercalcemia. Despite intensive diagnostic search for a neoplasm, no firm evidence of malignancy was found. However, at the autopsy, widely metastatic, papillary renal cell carcinoma was found originating in the left kidney. Many metastases showed central necrosis mimicking small cysts.

Unilateral nephrectomy selectively stimulates phospholipase D in the remaining kidney

The activation of phospholipase D in the kidney could be detected in vivo in rats treated with ethanol by the accumulation of phosphatidylethanol. Unilateral nephrectomy stimulated the activity of phospholipase D in the remaining kidney as indicated by an increase in the level of phosphatidylethanol. A significant increase in phosphatidylethanol level was observed as early as 5 min after contralateral nephrectomy and peak accumulation (200% of control) was observed after 15 min. The phosphatidylethanol level decreased again to the basal level after 2 h. The accumulation of phosphatidylethanol was specific for kidney and the product was localized primarily in the cortex. Phospholipase D activity in kidney cortical slices from untreated rats was stimulated in vitro by plasma obtained from unilaterally nephrectomized rats, indicating that circulating factors in the plasma are responsible for the activation of phospholipase D. The phospholipase D activation by plasma from uninephrectomized animals was selectively inhibited by the tyrosine kinase inhibitor genistein, but not by the protein kinase C inhibitor H7. It is concluded that phospholipase D activity is stimulated as an early signal transduction event in compensatory kidney growth.

Dissecting aortic aneurysm as a complication of generalized fibromuscular dysplasia

This is the first report of a dissecting aneurysm of the aorta caused by generalized vascular fibromuscular dysplasia. An 18-year-old black man suddenly developed paraparesis and bilateral pulse loss below the waist. An aortogram disclosed a dissecting aneurysm of the entire aorta and an obstruction of blood flow below the renal arteries. On postmortem examination, the dissection of the aorta was found to be due to fibromuscular dysplasia that affected not only the aorta, but multiple other arteries as well.

Effects of alcohols on mouse embryonal carcinoma-substrate adhesion

The effects of ethanol and closely related alcohols on the cell-substrate adhesion of embryonal carcinoma cells were studied in microtiter wells using the enzyme cytochemical alkaline phosphatase technique and an ELISA reader. Three embryonal carcinoma cell lines (NF-1, NE and F9) were used. Prior to plating of cells the wells were coated with laminin, fibronectin or collagen type I. NF-1 cells adhered only to laminin; NE adhered to all substrata and uncoated wells equally well; F9 adhered only to fibronectin and laminin coated wells. Ethanol reduced the binding of cells to laminin and collagen type I but did not affect the binding of NE or F9 cells to fibronectin. The effect of ethanols was dose dependent; it lasted as long as an adequate concentration of this alcohol was maintained in vitro, and it was reversible. Other short chain alcohols inhibited the binding of cells to laminin proportionately to their membrane/buffer partition coefficients. These data show that various embryonal carcinoma cells differ with regards to their capacity to adhere to different extracellular matrix components. Cell adhesion to some but not all substrates can be prevented by ethanol and related short chain alcohols. The effects of alcohols on the adhesion of embryonal carcinoma cells to various substrates may be relevant for the elucidation of the fetal alcohol syndrome.

[Mechanisms of epidermal growth factor activity]

Epidermal growth factor is a Mr 6045 polypeptide which binds to its own cell surface receptor and stimulates its intrinsic tyrosine kinase activity. Activation of this signal transducing system is believed to be involved in many physiological and pathophysiological processes. Some aspects of these processes are discussed in this review.

Plasma from uninephrectomized rats stimulates phospholipid methylation and arachidonic acid release in renal-cortical slices

Phospholipid methylation and arachidonic acid release in renal-cortical slices was investigated in vitro after addition of plasma from uninephrectomized or sham-operated rats. Plasma from uninephrectomized rats ('uni-plasma') stimulated phospholipid methylation when obtained within the first 3 h after uninephrectomy. With different amounts of added plasma a graded response in phospholipid methylation was obtained. Addition of 50 nM-12-O-tetradecanoylphorbol 13-acetate for 10 min to intact slices also stimulated phospholipid methylation, whereas incubation of slices before addition of 'uni-plasma' with 100 microM-1-(5-isoquinolinylsulphonyl)-2-methylpiperazine prevented it, suggesting that protein kinase C stimulates phospholipid methylation in renal-cortical slices. Plasma from uninephrectomized rats also stimulates [3H]arachidonic acid release from phosphatidylcholine (PtdCho) and phosphatidylethanolamine (PtdEtn) via activation of phospholipase A2. Two mechanisms of phospholipase A2 activation are proposed: first, in which it is activated by protein kinase C and releases 3H radioactivity from PtdCho, and second, in which phospholipase A2 is stimulated by Ca2+ ions and releases 3H radioactivity from PtdEtn.

Epidermal growth factor stimulates the incorporation of phosphate into phosphatidic acid and phosphoinositides but does not affect phosphoinositide breakdown by phospholipase C in renal cortical slices

The effects of epidermal growth factor (EGF) on the metabolism of phosphatidic acid and phosphoinositides were examined using renal cortical slices labelled with either sodium [32P]orthophosphate or myo-[3H]inositol. EGF was found to increase the incorporation of phosphate into phosphatidic acid and phosphoinositides. This effect is not dependent on external calcium and is inhibited by 12-O-tetradecanoylphorbol 13-acetate (TPA). When phospholipids were prelabelled, EGF did not decrease the level of 32P in phosphatidic acid and phosphoinositides, and EGF did not affect the formation of inositol phosphates or the concentration of cAMP and cGMP in renal tissue. The results show that EGF stimulates the incorporation of phosphate into phosphatidic acid and phosphoinositides, but does not affect breakdown of phosphoinositides by phospholipase C in renal cortical slices.