Ultrastructural observations on the histogenesis of localized fibrous tumours of the pleura (benign mesothehoma)

Summary Five localized fibrous tumours of the pleura (benign mesothelioma) were studied ultrastructurally in order to elucidate their histogenesis. The histological subtypes of this benign fibrous lesion of the visceral pleura, i.e. the cellular, the collagenous, and the hyaline, were separately analysed.The tumours are composed of undifferentiated mesenchymal cells, intermediate and differentiated fibroblasts as well as collagenous interstitial tissue. The varying distribution of these cell elements account for the various histological subtypes. Morphological similarities between the mesenchymal tumour cells and the superficial mesothelial cells, which are always separated from the true tumour tissue by an intact basement membrane, were not observed.The different cellular elements can be regarded as parts of a continuous spectrum of cytodifferentiation, in which the mature fibroblasts are derived via intermediate forms from the undifferentiated cells. It is concluded that the localized fibrous tumours of the pleura arise from immature mesenchymal stem cells, which seems to be normally found in the submesothelial layer of the visceral pleura.     

The flow resistance of the spiral artery and the related intervillous space in the rhesus monkey placenta

Uteroplacental arteries of 4 rhesus monkeys were cannulated at their myometrical portions and perfused with dextran solutions and blood. Pressure-flow curves were obtained for the spiral artery and the related intervillous space, i.e. for the functional cotyledonary unit of the haemochorial villous placenta.For a flow of 3 ml·min^–1, which is probably the normal rate of flow through the spiral artery, the pressure at the entry of the spiral artery was found to be 13–18 mm Hg (1.7–2.4 kPa) during uterine relaxation (uterine diastole). There was a direct proportional relationship between the spiral artery flow and the pressure difference between the spiral artery and the amniotic fluid; the pressure difference per flow (the resistance of the cotyledonary unit) was found to be 1–3 mmHg·ml^–1·min (8–24 kPa·ml^–1·s).It is concluded that the spiral artery and the related intervillous space do not offer a limiting resistance to maternal blood flow in the absence of uterine contractions.This investigation was supported by the Deutsche Forschungsgemeinschaft (Mo 105/8).     

Extended radical lymphadenectomy in patients with urothelial bladder cancer: results of a prospective multicenter study

PURPOSE: Previous studies demonstrate a positive correlation between postoperative survival and the extent of pelvic lymphadenectomies in patients with bladder cancer. However, the distribution of nodal metastases has not been examined in sufficient detail. Therefore, we conducted a comprehensive prospective analysis of lymph node metastases to obtain precise knowledge about the pattern of lymphatic tumor spread. MATERIALS AND METHODS: Between 1999 and 2002 we performed 290 radical cystectomies and extended lymphadenectomies. Cranial border of the lymphadenectomy was the level of the inferior mesenteric artery, lateral border was the genitofemoral nerve and caudal border was the pelvic floor. We made every effort to excise and examine microscopically all lymph nodes from 12 well-defined anatomical locations. RESULTS: Mean total number and standard deviation of lymph nodes removed was 43.1 +/- 16.1. Nodal metastases were present in 27.9% of patients. The percentage of metastases at different sites ranged from 14.1% (right obturator nodes) to 2.9% (right paracaval nodes above the aortic bifurcation). By studying cases of unilateral primary tumors or with only 1 metastasis we observed a preferred pattern of metastatic spread. However, there were many exceptions to the rule and we did not identify a well-defined sentinel lymph node. CONCLUSIONS: We strongly recommend extended radical lymphadenectomy to all patients undergoing radical cystectomy for bladder cancer to remove all metastatic tumor deposits completely. The operation can be conducted in routine clinical practice and our data may serve as a guideline for future standardization and quality control of the procedure.     

Cyto- and histomorphogenesis of the prostate carcinoma

Summary The fundamental histologie proliferation patterns of the prostate carcinoma are presented by the glandular and solid and/or cribriform structures. These were ultra-structurally analyzed from 28 carcinomas based on the cell forms in prostate carcinomas, which were already defined by electron microscope. These are characterized by their different cytoplasmic differentiation, whereby the singular cell types each represent a different functional state of a common tumor cell. The results indicate that the prostatic carcinoma develops morphologically in phases. The well-known growth patterns of the tumor are equivalent to its different states of development. In the first phase, a pattern develops out of a tumor stem cell (perhaps primary atypical reserve cell), which is either glandular or solid/cribriform, whereas this depends on the trend of the tumor cells to differentiate. The glandular structure possesses centrifugally proliferated glandular, often functionally deranged tumor cells, and shows signs of early stromal infiltration. The solid/cribriform pattern consists of centripetal proliferated, often less-differentiated tumor cells with or without lumen formation, and a peripheral layer of basal cells, whereby the idiopathic stroma architecture remains as it is. In the successive phase, stroma infiltration and destruction is distinctly marked during tumor growth. Histologically, one often sees at this stage an anaplastic pattern; however, ultrastructurally its origin can be recognized as being glandular or solid/ cribriform. The advanced stages of the tumor are furthermore characterized by a mixed cell pattern with all states of differentiation and by progressing tumor cell degeneration.Supported by the foundation: Hamburger Stiftung zur Förderung der Krebsbekämpfung     

Zur Pathologie der Xanthofibrogranulomatose

Summary Two cases are described of an extensive sclerosing lesion involving the retroperitoneum, mesentery, mediastinum and epicardium which is referred as Xanthofibrogranulomatosis. The term was chosen on histological criteria: granulomatous infiltration of chronic inflammatory cells without necrosis, proliferation of spindle-shaped, lipid-laden histiocytes, aggregation of xanthomatous cells and increased production of reticulin and collagenous fibers. Furthermore the name suggests that the lesion tends to be generalized although it does not represent a true neoplasm. In nearly all cases the changes are localized in the retroperitoneal adipose tissue extending to the renal hilus and enveloping the aorta and kidneys; other organs such as adrenals and pancreas are also often surrounded. The frequent cardiac manifestations (14 of 22 cases) with sclerosis of the epicardial fat especially in the right atrioventricular region are conspicous. Moreover involvement of organs may be found, e.g. the lungs or the posterior lobe of the pituitary gland in our cases. Generally the spread of the process shows a striking relation to large blood vessels. However, the distribution lacks uniformity. The characteristic localization and histology allows the distinction of Xanthofibrogranulomatosis from other well known disorders such as Ormond's, retroperitoneal fibrosis, panniculitis (Weber-Christian disease) and histiocytosis X (Hand-Schüller-Christian). The etiology and pathogenesis of Xanthofibrogranulomatosis are uncertain. Perhaps an autoimmune mechanism involving the fat cell membrane may play a part in the genesis of this chronic inflammatory sclerosing process. As long as no rational specific therapy exists, we must interpret the xanthofibrogranulomatous lesion as a slowly but irreversibly progressing disease which is clinically comparable with a malignant tumor.

     

Ultrastructure and formal pathogenesis of embryonal rhabdomyosarcoma (author's transl)]

An embryonal rhabdomyosarcoma of the nasopharynx of a 10 year old boy is analysed with light and electron microscopy. With regard to cell shape and cytoplasmic features the following four tumour cell types could be distinguished: 1. Undifferentiated mesenchymal cells with a big loosely packed nucleus and a small cytoplasmic rim with only few cell organelles; 2. Undifferentiated tumour cells with a broad cytoplasmic body which contains a dense network of nonspecific intermediate filaments with a diameter of about 100 A; 3. Immature rhabdomyoblasts with randomly orientated specific myofilaments; 4. Fully differentiated rhabdomyoblasts with well developed myofibrils often showing a sarcomeric pattern. Glycogen deposits which were seen in great masses in many tumour cells were regarded to result from degenerative processes within the tumor. The cellular stages in the development of rhabdomyoblasts are basically identical to those known from the embryogenesis and regeneration of striated muscle. From these observations the two following developmental pathways are suggested: 1. Origin of the tumour from an undifferentiated mesenchymal cell; 2. Atypical regeneration of striated muscle which terminates in malignant progressive tumour growth. At present, the body of information about rhabdomyosarcomas supports the assumption of an origin from immature mesenchymal cells. Nevertheless, the second theory cannot be totally excluded.