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Introduction

Deposits of endogenous body constituents or exogenous materials in amounts sufficient to deform structure and impair function can occur virtually anywhere in the body. Deposits of endogenous materials in the lungs or airways cause a variety of diseases (Table 64-1). These may have different clinical manifestations, depending on localization (i.e., pulmonary parenchyma or conducting airways). This chapter deals with a few of these manifestations: amyloidosis; diffuse pulmonary calcification; alveolar microlithiasis; diffuse alveolar hemorrhage (DAH) syndromes; and idiopathic pulmonary hemosiderosis. Others are discussed elsewhere in this text.

Table 64-1Depositional Diseases of the Lungs

Amyloidosis

Characteristics of amyloid and the various forms of pulmonary amyloid are considered below.

Nature of Amyloid

Amyloidosis refers to the extracellular deposition of amyloid, a fibrillar, proteinaceous, insoluble material that has characteristic light, ultrastructural, and histochemical features (Fig. 64-1). Electron microscopic examination of amyloid reveals a dominant (95%) fibrillar component with distinctive periodicity, associated with a lesser (5%) pentagonal doughnut-shaped glycoprotein component, physically and chemically identical in all forms of amyloid, which is derived from a soluble plasma protein, soluble amyloid P protein (SAP). Amyloid also includes various glycosaminoglycans and certain apolipoproteins (E and J). Radiographic diffraction studies of amyloid show the fibrils to be arrayed in a β-pleated sheet configuration. This accounts for the ordered binding of the histochemical stain Congo red such that Congo red–stained amyloid appears apple-green under polarized light.1,2 When amyloid is deposited in tissues it may produce atrophy of parenchymal cells (e.g., glomeruli), interference with mechanical function (e.g., heart and lungs), or impaired vasoconstriction of blood vessels, leading to hemorrhage (e.g., lungs and gastrointestinal tract). Other mechanisms of tissue injury are also hypothesized including direct tissue toxicity.3

Figure 64-1

Amyloid deposition. A. Amyloidoma. Cut surface of lung with white arrows indicating a dense, wax-like lesion that is characteristic of nodular amyloid. Incidental finding at autopsy. (Used with permission of Leslie A. Litzky, MD, Department of Pathology and Laboratory Medicine, Hospital of the University of Pennsylvania, Philadelphia.) B. The typical amorphous appearance of amyloid is seen deposited within the wall of a pulmonary venule. Green birefringence on polarized light examination after staining with Congo red will confirm the amyloid nature of the deposit (H&E ×700). C. Amorphous amyloid in the alveolar interstitial space. Arrow indicates a thickened alveolar septum (H&E ×420).

While the main fibrillar component of amyloid can be derived from any one of 27 precursor proteins,2 only a ...

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