This injury to the epithelial basal lamina results in inflammatory cells and plasma proteins leaking into the alveolar space and forming fibrin, resulting in an initial fibroblast driven intra-alveolar fibroproliferation. The fibroblasts differentiate into myofibroblasts and continue to form fibrosis resulting in intra-alveolar fibroinflammatory buds (Massons Bodies) that are characteristic of organizing pneumonia. These Massons bodies consist of inflammatory cells contained in an extracellular matrix consisting of type I collagen, fibronectin, procollagen type III, tenascin C and proteoglycans. Angiogenesis , or the formation of blood vessels, occurs in the Massons bodies and this is driven by vascular endothelial growth factor. Remodeling occurs, resulting in the intra-alveolar fibroinflammatory buds (Massons Bodies) moving into the interstitial space and forming collagen globules that are then covered by type 1 alveolar epithelial cells with well developed basement membranes. These type 1 alveolar epithelial cells (pneumocytes) then proliferate, restoring the continuity and function of the alveolar unit.
Cyanosis is the change of body tissue color to a bluish-purple hue as a result of having decreased amounts of oxygen bound to the hemoglobin in the red blood cells of the capillary bed. Body tissues that reflect cyanosis are usually in locations where the skin is thinner, including the mucous membranes, lips, nail beds, and ear lobes. Some medications containing amiodarone or silver, Mongolian spots, large birth marks, and the consumption of food products with blue or purple dyes can also result in the bluish skin tissue discoloration and may be mistaken for cyanosis.Cyanosis is further classified into central cyanosis vs. peripheral cyanosis. Pathophysiology
The mechanism behind cyanosis is different depending on whether it is central or peripheral. Central cyanosis
Central cyanosis is caused by a decrease in arterial oxygen saturation (SaO2) and begins to show once the concentration of deoxyhemoglobin in the blood reaches a concentration of ≥ 5.0 g/dL (≥ 3.1 mmol/L or oxygen saturation of ≤ 85 %). Causes of central cyanosis are discussed below. Peripheral cyanosis
Peripheral cyanosis happens when there is increased concentration of deoxyhemoglobin on the venous side of the peripheral circulation. In other words, cyanosis is dependent on the concentration of deoxyhemoglobin. Patients with severe anemia may appear normal despite higher than normal concentrations of deoxyhemoglobin. On the other hand, patients with increased amounts of red blood cells (e.g. polycythemia vera) can appear cyanotic even with lower concentrations of deoxyhemoglobin.