Aorticopulmonary Paraganglioma (Aortic Body Tumor): Report of a Case

A case of aorticopulmonary paraganglioma in a 57-year-old man is described. The tumor comprised nests of uniform cells in a fibrovascular stroma. Electron microscopy revealed abundant neurosecretory granules, and S-100 protein staining demonstrated scattered sustentacular cells at the periphery of typical zellballen. The findings in this case correlated with those of studies on the prognosis for extraadrenal paragangliomas.     

Cytokeratin-Containing Globular Filamentous Bodies in Renal Oncocytoma

Eighty-four cortical neoplasms were studied for cytokeratin and vimentin expression by immunohis-tochemistry and for intermediate filament aggregates by electron microscopy. Twenty oncocytomas expressed cytokeratin, 16 in a distinctive punctate pattern. These same 16 tumors also contained small globular filamentous bodies (GFB) by electron microscopy. The GFB were characterized by a matrix of intermediate-sized filaments with incorporation of diverse cell organelles such as endoplasmic reticulum, lysosomes, mitochondria, and lipid. The GFB were not within a unit membrane. Although 11 of 64 carcinomas also contained intermediate filament aggregates, only 2 of these solely expressed cytokeratin, and this was restricted to a few cells in small foci. Small GFB were also present in 5 carcinomas by electron microscopy. Three mixed clear and granular cell carcinomas contained only rare cells, whereas 2 sarcomatoid carcinomas, both of rhabdoid cell phenotype, contained numerous GFB that coexpressed vimentin and cytokeratin. Cytokeratin-containing GFB are common in oncocytomas but are uncommon in carcinoma, and, when numerous, may provide a diagnostically useful immunohistochemical feature with which to distinguish oncocytoma from its carcinoma congeners.     

Cell Interposition in Glomerular Capillary Walls in Cryoglobulinemic Glomerulonephritis (CRYGN). Ultrastructural Investigation of 23 Cases

The present report describes ultrastructural findings on twenty-three cases of CRYGN showing membranoproliferative pattern under light microscopy. Attention was paid to the presence of double contoured peripheral basement membranes and to the characteristics of the interposed cells. The latter, according to the well known characteristics of membranoproliferative GN, are thought to be mesangial in nature. In fact, mesangial cells were found in 8 cases only, always associated with monocytes. Only monocytes were recorded in 12 cases, whereas in other 3 cases double contours were not connected to cell interposition.

Despite similarities under light microscopy, CRYGN is therefore rather different from idiopathic membranoproliferative GN because of the prevalence of exudative changes, mainly due to monocyte infiltration, over proliferative lesions.     

Ultrastructural Heterogeneity in Malignant Fibrous Histiocytoma of Soft Tissue

Five soft tissue sarcomas with histological features of malignant fibrous histiocytoma were selected to illustrate their ultrastructural heterogeneity. One case displayed the mixture of fibroblastic and histiocytic cells characteristic of the majority of malignant fibrous histiocytomas. In 1 case the tumor was composed entirely of primitive mesenchymal cells. The other 3 cases showed lipogenic, neurogenic, and “granular-cell” differentiation, respectively. These findings emphasize the important role of electron microscopy in the precise diagnosis and classification of malignant fibrous histiocytoma.     

Extrathoracic Mesothelial Proliferations and Their Mimics

Mesothelial proliferations, either reactive or neoplastic in nature, often pose difficult diagnostic dilemmas. Electron microscopy continues to be a gold standard in the identification of mesothelial differentiation. However, it is very common to apply long panels of antibodies for that purpose. In most cases, light microscopy and immunohistochemistry will solve the problem. However, the definitive, specific, and sensitive immunohistochemical marker is still lacking. This is particularly true in peritoneal and testicular mesothelial tumors, in which common embryologic origin with epithelial elements results in overlapping immunohistochemistry and morphology. The particularities of peritoneal and testicular mesothelial proliferations, and the main tumors that may mimic them in these sites, as well as the value and limitations of immunohistochemistry and electron microscopy in their differential diagnosis are the subject of this review.     

Ultrastructural Studies of Glioma Stem Cells/Progenitor Cells

Although the ultrastructural features of several brain tumor cells have been studied in details, the ultrastructure of glioma stem cells/progenitors cells (GSPC) has rarely been reported. In this paper, the authors describe the ultrastructural features of GSPCs isolated from both a glioma tissue and the human glioma cell SHG-44 cell line. The ultrastructural features of the two kinds of GSPCs were similar, with relatively developed mitochondria, Golgi apparatuses, ribosomes, undeveloped rough endoplasmic reticula, seldom lysosomes and no typical autophagosomes, and high nuclear–cytoplasmic ratio. Their nuclei, frequently containing huge amounts of euchromatin and a small quantity of heterochromatin, were mostly globular; and the majority of the nuclei had only one nucleole. Typical apoptotic cells could hardly be found in tumor spheres, and between adjacent cells there were cell junctions, which probably were incompletely developed desmosomes or intermediate junctions. In conclusion, their ultrastructural features showed that GSPCs were at the primary stage of differentiation, and could even partially reveal the underlying reasons for the malignant proliferation and differential inhibition of GSPCs.     

Morphologic Heterogeneity of Renal Light-Chain Deposition Disease

Light-chain deposition disease (LCDD) of the kidney is defined as deposition of monotypic light chains (LC) within glomerular (GBM) and tubular (TBM) basement membranes. The morphologic features of pure renal LCDD have been presented only in case reports or small series. The aim of this study was to perform a comprehensive evaluation of the light (LM), immunofluorescence (IF), and electron microscopic (EM) features of pure renal LCDD in a large series of biopsies. Out of 46 cases assembled, 42 had multiple myeloma, 2 had monoclonal gammopathy of unknown significance, and in 2 patients no lymphoproliferative disease was identified. The most common LM lesion of LCDD, nodular glomerulosclerosis, was present in only 14 (30%) cases. GBM and/or TBM thickening was found in 3 (6%), mild to moderate mesangial matrix increase in 12 (23%), and unremarkable glomeruli and tubules were seen in 15 (32%) cases. Forty-two had IF and 40 (92%) showed characteristic linear LC immunoreactivity (24 kappa, 16 lambda) along GBM and/or TBM. Among 39 cases in which IF and EM was available, 25 (64%) were positive by both. Two (6%) were negative by IF, but had deposits by EM. In 12 (30%) with immunoreactivity to LC (4 kappa, 8 lambda), no deposits were identified ultrastructurally. This study shows heterogeneous LM lesions in pure LCDD cases. LM alone may be suspicious but not diagnostic of LCDD. Immunofluorescence is more sensitive than EM for detection of LC for the definitive diagnosis of LCDD. This study supports the importance of utilizing kappa and lambda stains in the routine IF panel for diagnosis of LCDD.     

Immunoelectron Study of Pancreatic Carcinomas Using Antibodies to Gastrointestinal Hormones

The aim of this study was to investigate the ultrastructural appearance of pancreatic adenocarcinoma combined with glucagon and gastrin/cholecystokinin (CCK) expression. The authors investigated the ultrastructure and the immunocytochemistry of 12 human pancreatic cancer specimens and used 3 chronic pancreatitis samples and 6 adjacent histological normal pancreatic tissues (away from the tumor) as controls. The ultrastructural study revealed that chronic pancreatitis tissues were characterized by alterations of the secretory cells. The enzymic and secretory changes were confirmed by electron immunogold results. Glucagon appeared to be located not only in islet α cells but also in intermediate α acinar cells. The changes were more significant in adenocarcinoma cases. Abnormality in the immunoreaction of the peptides was indicated not only in the tumor area but also in the islets near the cancer. Cells immunoreactive with antibodies were found in all 12 adenocarcinoma cases. Abnormal co-location of both hormones in the same type of endocrine cell was also found. Moderately to poorly differentiated adenocarcinomas were poorly granulated compared with differentiated tumors. Increased and ectopic gastrin/CCK expression was correlated with pancreatic adenocarcinomas exhibiting poor histological grade and neoplastic endocrine cells, providing a potential marker for pancreatic adenocarcinomas with aggressive behavior.     

Protective effects of melatonin against spinal cord injury induced oxidative damage in rat kidney: A morphological and biochemical study

Spinal cord injury (SCI) induced oxidative stress affects multiple organ systems including the kidney. We studied the possible protective effects of melatonin on SCI-induced oxidative damage in renal tissues of rats. Wistar albino rats (n = 24) were exposed to SCI and divided into vehicle- or melatonin-treated SCI groups. Melatonin was administred intraperitoneally at a dose of 10 mg/kg for seven days. Renal tissues were investigated by light and electron microscopy. Furthermore, tissue malondialdehyde (MDA) and glutathione (GSH) levels and myeloperoxidase (MPO) and superoxide dismutase (SOD) activities were also determined. In the vehicle-treated SCI group, the renal histology was disturbed compared to controls, whereas the melatonin-treated SCI group showed significantly reduced degeneration of renal tissue as seen by both light and electron microscopy. MDA levels, MPO and SOD activities were increased and GSH levels were decreased in the vehicle-treated SCI group compared to controls. On the other hand, decreased MDA levels and MPO activities and increased GSH levels were observed in the melatonin-treated SCI group compared to vehicle-treated SCI group. These results showed that experimentally induced SCI caused oxidative stress in the rat kidney, whereas melatonin treatment reduced oxidative stress, suggesting that it may be used as a complementary therapy of renal problems occurring following SCI.