Pleura structure

The pleural tissue is a typical connective tissue that consists mostly of matrix the fibrous proteins (collagen, elastin), and mucopolysaccharides, and a few scattered mesothelial cells, capillaries, venules, and ducts. Anatomists have defined several layers (Fig. 3.4) for each of the pleura. Layers 3 and 5 in Fig. 3.4 contain an abundance of fibrous protein, especially elastin. Both the interstitial (Layer 4) and mesothelial (1 and 2) layers contain capillaries of the vascular system and lymphatic channels. The matrix (ground substance) gives the pleura structural integrity and is responsible for its mechanical properties such as elasticity and distensibility. 

Fig. 3.4 The structure of the pulmonary pleura 1, mesothelial layer 2, submesothelial layer 3, external elastic layer 4, interstitial layer 5, internal elastic layer B, blood capillary net E, elastic fiber net L, lymph vessel net. 

The tissues of the pleura are considered to be relatively inert, functioning mainly as support structures or frameworks for the ducts and capillaries. The mesothelial cells in these tissues are sparse and their metabolic activities, especially as producers of fibrous proteins required to maintain healthy tissue, have not been fully explored. The mechanisms that lead to increased protein production (i.e., plaque formation) remain under study. 

For more detailed information on the respiratory tract, the pleura, and the lymphatic system, consult Gray s Anatomy or other standard medical texts. A comprehensive review of the lung and its structure and function is presented in Nagaishi (1972). 

Pleurisy Inflammation of the pleura, the membranes that line all internal and external structures of the lung and thoracic cavity. 

Stoermer, E. F., Pankratz, H. S., and Bowen, C. C. Fine structur of the diatom Amphi-pleura pellucida. II. Cytoplasmic fine structure and frustule formation. Amer. J. Bot. 52, 1067-1078(1965). 

Figure 3.6. Structure of peritoneum and pleura. The peritoneum and pleura contain a thin mesothelial cell lining, a basement membrane, connective tissue, and smooth muscle cells.

Tyler WS, Julian MD. Gross and subgross anatomy of the lungs, pleura, connective tissue septa, distal airways, and structural units. In Comparative Biology of the Normal Lung, Parent RA, ed. CRC Press Boca Raton, FL, 1991, pp. 37-48. 

Removal of noninfected leads is not indicated (Class III) if patients have a life expectancy of less than 1 year and in patients with known anomalous placement of leads through structures other than normal venous and cardiac structures (e.g., subclavian artery, aorta, pleura, atrial or ventricular wall, or mediastinum) or through a systemic venous atrium or systemic ventricle. Additional techniques including surgical backup may be used if the clinical scenario is compelling. 

This applies only if the dissection of structures at risk is not possible using air or glucose In selected patients RFA is possible even if extrahepatic tumor is present. Note that in carefully selected patients extrahepatic tumors (e.g. bone, lung, pleura or soft tissue) can also be addressed by RFA... 

Other tissues should not be accepted for quantification. Samples with pleural thickening, pleural plaque and tumour tissue contain few particles and will result in false-negative counts. The particle content of lymph nodes may be influenced by their anatomical location. The parietal pleura is a very heterogeneous phase. Anatomical structures resorbing pleural fluid from the pleural space may trap and concentrate particles and fibers in localised areas called black spots because of their pigmentation (Boutin et al. 1996 Mitchev et al. 2002). All these samples are not suitable for routine purposes, but maybe used for research purposes, e.g. when studying the migration of fibers in the human body. 

The typical mesothelioma found at autopsy is a firm and hard mass of whitish or grayish tissue that envelops adjacent anatomical structures, including the lung and the mediastinal and hilar vessels. In most cases, the pleural space is obliterated. Gelatinous material is often present in small cysts that are located inside the tumor. Most tumors will spread diffusely, but in some cases they might include areas that are well circumscribed. The tumor starts on the parietal surface of the pleura but soon reaches the visceral pleura. Consequently, tumor deposits can be found on both the parietal and the visceral pleura. Approximately 50% of all patients with mesothelioma will have distant metastases. Lymph nodes are... 

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