Electron microscopy of desquamative interstitial pneumonia

Smoking-Related Interstitial Lung Disease: Historical Perspective and Advances in the Twenty-first Century

In the twenty- first century, there is widespread agreement that in addition to lung cancer, emphysema, and chronic bronchitis, cigarette smoking causes accumulation of pigmented macrophages, interstitial fibrosis, and Langerhans cell proliferation in various permutations. These histologic changes remain subclinical in some patients and produce clinical manifestations and imaging abnormalities in others. Debate surrounds terminology of these lesions, which are often grouped together under the umbrella of "smoking-related interstitial lung disease." This review summarizes modern concepts in our understanding of these abnormalities and explains how the recognition of smoking-related interstitial fibrosis has advanced the field.

Five simple reasons to discard DIP, or why we should stop calling dolphins big fish

The aim of this review is to explain why the term 'desquamative interstitial pneumonia' (DIP) should be discarded and replaced with modern terminology. Reason 1: DIP is a misnomer. Within a few years after the term was coined, it was shown that the airspace cells in DIP are macrophages not desquamated pneumocytes. Reason 2: As a result of overly simplistic and poorly defined histologic criteria, DIP is currently a mixed bag of smoking-related diseases and unrelated processes in never-smokers. Reason 3: DIP obfuscates the modern concept that smoking causes some forms of parenchymal lung disease. Despite the fact that >80% of cases of DIP are caused by smoking, it is currently classified as a 'smoking-related idiopathic interstitial pneumonia', an oxymoron. Reason 4: The premise that the presence of numerous macrophages within airspaces defines an entity creates problematic histologic overlap with other lung diseases that may feature prominent airspace macrophages. Reason 5: DIP is outdated. It was coined in 1965, when many entities in interstitial lung disease had not been described, smoking-related interstitial lung disease was an unknown concept, computed tomograms of the chest had not been introduced and immunohistochemistry was unavailable. We suggest a way forward, which includes eliminating the term DIP and separating smoking-related lung abnormalities (including accumulation of pigmented airspace macrophages) from cases characterised by numerous non-pigmented macrophages in never-smokers. The laudable goal of smoking cessation is not served well by muddying the relationship between smoking and lung disease with inaccurate, outdated terminology.

Desquamative interstitial pneumonia: a systematic review of its features and outcomes

Background

Desquamative Interstitial Pneumonia (DIP) is a rare form of idiopathic interstitial pneumonia (IIP). Data on clinical features, aetiology, prognosis and effect of treatment strategies are limited. We aimed to collect all published cases to better characterise DIP.

Methods

A systematic literature search was performed for all original cases of adult patients with histopathologically-confirmed DIP. Individual patient data were extracted and summarised.

Results

We included 68 individual cases and 13 case series reporting on 294 cases. Most common presenting symptoms were dyspnoea and cough. Pulmonary function showed a restrictive pattern (71%) with decreased diffusion capacity. We found a high incidence (81%) of ever smoking in patients with DIP and 22% of patients had other (occupational) exposures. Characteristic features on high-resolution computed tomography (HRCT) scan were bilateral ground-glass opacities with lower lobe predominance (92%). Treatment and duration of treatment widely varied. Initial response to treatment was generally good, but definitely not uniformly so. A significant proportion of patients died (25% of individual cases) or experienced a relapse (18% of individual cases).

Conclusion

DIP remains an uncommon disease, frequently but not always related to smoking or other exposures. Furthermore, DIP behaves as a progressive disease more often than generally thought, possibly associated with different underlying aetiology.

This systematic review is the most comprehensive collection of published cases of DIP to date and yields novel information about aetiology, clinical characteristics, radiology and pathology features, treatment and outcomes.http://bit.ly/394YRPv

Histopathological Changes in the Lungs in Patients with Malignant Tumors Treated with Bleomycin

Histopathological changes in the lungs of 7 patients with malignant tumors treated with Bleomycin are characterized by hyperplasia and endoalveolar migration of type II pneumocytes and macrophages, hyaline membrane formation and the appearance of newly formed reticular and collagen fibers within the alveolar septa and hyperplasia of muscular fibers of respiratory bronchioli. These findings are consistent with the diagnosis of interstitial pneumonia, the morphologic pattern of which is often complicated by either pre-existing pulmonary damage or supervening lesions. The direct or indirect role of bleomycin in the etiology and pathogenesis of the pulmonary disease as described above seems to be ascertained, since the pathological findings are in keeping with clinical and radiological data.

Alveolar brush cells in an infant with desquamative interstitial pneumonitis

A full-term infant developed bilateral pneumothoraces and respiratory distress shortly after birth, despite initially good Apgar scores. Persistent tachypnea, hypoxemia, and a chest X-ray remarkable for diffuse alveolar and interstitial infiltrates prompted a lung biopsy at 4 months of age. The biopsy revealed desquamative interstitial pneumonitis with the unique demonstration by electron microscopy of numerous alveolar brush cells. Respiratory brush cells occur normally in the trachea and bronchi of humans and mammals. Although identical cells have been noted in the alveoli of rats, they have never been reported in the alveoli of humans. We present the first electron microscopical demonstration of the alveolar brush cell in humans.

Oxidant-mediated epithelial cell injury in idiopathic pulmonary fibrosis

Lung inflammatory cells of patients with idiopathic pulmonary fibrosis (IPF) were evaluated for their ability to injure 51Cr-labeled AKD alveolar epithelial cells in the presence and absence of IPF alveolar epithelial lining fluid (ELF). The IPF cells were spontaneously releasing exaggerated amounts of superoxide (O.2) and hydrogen peroxide (H2O2) compared with normal (P less than 0.02). Cytotoxicity of the AKD cells was markedly increased when the IPF inflammatory cells were incubated with autologous ELF (P less than 0.02). The majority of IPF patients had ELF myeloperoxidase levels above normal (P less than 0.002). Incubation of IPF ELF with AKD cells in the presence of H2O2 caused increased cellular injury (P less than 0.01 compared with control), which was suppressed by methionine, a myeloperoxidase system scavenger. IPF patients with high concentrations of ELF myeloperoxidase deteriorated more rapidly than those with low ELF myeloperoxidase (P less than 0.05). Thus, IPF is characterized by an increased spontaneous production of oxidants by lung inflammatory cells, the presence of high concentrations of myeloperoxidase in the ELF of the lower respiratory tract, and a synergistic cytotoxic effect of alveolar inflammatory cells and ELF on lung epithelial cells, suggesting oxidants may play a role in causing the epithelial cell injury of this disorder.

Pulmonary and generalized lysosomal storage induced by amphiphilic drugs

Administration of amphiphilic drugs to experimental animals causes formation of myelinoid bodies in many cell types, accumulation of foamy macrophages in pulmonary alveoli and pulmonary alveolar proteinosis. These changes are the result of an interaction between the drugs and phospholipids which leads to an alteration in physicochemical properties of the phospholipids. Impairment of the digestion of altered pulmonary secretions in phagosomes of macrophages results in accumulation of foam cells in pulmonary alveoli. Impairment of the metabolism of altered phospholipids removed by autophagy induces an accumulation of myelinoid bodies. The administration of amphiphilic compounds thus causes pulmonary intra-alveolar histiocytosis which is a part of a drug-induced lysosomal storage or generalized lipidosis. The accumulation of drug-lipid complexes in myelinoid bodies and in pulmonary foam cells may lead to alteration of cellular functioning and to clinical disease. Currently over 50 amphiphilic drugs are known. Unique pharmacological properties necessitate clinical use of some of these drugs. The occurrence and severity of potential clinical side effects depend on the nature of each drug, dosage and duration of treatment, simultaneous administration of other drugs and foods, individual metabolic pattern of the patient and other factors. Further studies on factors preventing and potentiating adverse effects of amphiphilic drugs are indicated.

Mechanisms of tissue injury in desquamative interstitial pneumonitis

To evaluate a contribution of immunologic factors to the pathogenesis of desquamative interstitial pneumonitis (DIP), lung biopsy specimens from four patients were studied for immunoglobulin deposits in tissue and cellular characteristics by immunologic, ultrastructural and histochemical methods. Accumulations of large cells with vacuolated cytoplasm within the distal air spaces and marked increase in the numbers of type II pneumocytes lining pulmonary alveoli were observed in all cases. The cells in air spaces were identified as macrophages containing intracellular lysozyme and alpha-naphthyl acetate esterase. Deposits of immunoglobulin G(IgG) and the third component of complement were found in distal air spaces and on the surfaces of the accumulated macrophages. The interstitial fibrosis was not a significant feature in out patients. Circulating immune complexes and a decreased IgG level were detected in serum during the acute phase of the disease. IgG levels returned to normal and were no longer detectable during convalescence in one patient followed sequentially. The formation and deposition of complement-fixing antibody and/or immune complexes may be responsible for the local accumulation and activation of macrophages and for tissue damages. Release of lysosomal enzymes by alveolar macrophages phagocytosing the complexes could also contribute to the alveolar injury, whereas the proliferation of type II pneumocytes may be a reparative tissue reaction to immunologically-mediated injury.

"Blue bodies" in a case of cryptogenic fibrosing alveolitis (desquamative type) an ultra-structural study

A patient with cryptogenic fibrosing alveolitis, with both mural and desquamative features, had two lung biopsies at the times of coronary artery surgery. These lung specimens were studied, using light and electron microscopy, with immunofluorescence techniques and electron microanalysis. In addition to the typical changes of cryptogenic fibrosing alveolitis previously reported, we found "blue-staining bodies" within alveolar macrophages and giant cells. These bodies were 15--25 micrometer in diameter with an iron rich outer rim and core of connective tissue mucin--possibly chondroitin sulphate or dermatan sulphate. It seems unlikely that these "blue bodies" were due to fibreglass dust to which the patients had had a trivial exposure, but their exact nature and significance remains unclear.

Fibrosing alveolitis

Fibrosing alveolitis is a disease of unknown cause mainly involving the gas-exchanging portions of the lungs. It may occur in isolation and be called cryptogenic or idiopathic, in which case the clinical manifestations are mainly respiratory, or it may be associated with other disorders, such as rheumatoid arthritis. The histopathologic abnormalities of the pulmonary tissue are identical in either instance. Other names used for the disease have included usual interstitial pneumonia, desquamative interstitial pneumonia and the Hamman-Rich syndrome; these terms may describe different stages of the same pathologic process. Many authors in North America and those in the United Kingdom favour the term fibrosing alveolitis when describing chronic interstitial pneumonias. There may be accompanying nonspecific Immunologic abnormalities, which may denote that fibrosing alveolitis is part of the wide spectrum of diseases known as connective tissue disorders. Recently immune complexes have been found in the lung parenchyma; they probably result in the granulocyte destruction and reticuloendothelial proliferation seen in the acute phase of the disease.There are no specific diagnostic tests for the disease apart from lung biopsy, which can be performed at the time of thoracotomy or transbronchially, with the use of a flexible fibreoptic bronchoscope. Lavaged cells from the alveoli have also been obtained via the bronchoscope; in persons with fibrosing alveolitis a high proportion of these cells are neutrophils, and after corticosteroid treatment the proportion decreases. The progress of the disease can be followed by examination of these washings as well as by lung scanning with gallium-67 citrate. Newer methods of treatment using combinations of corticosteroids and immunosuppressant drugs are being evaluated and are initially proving to be successful.

Surface and transmission ultrastructural characteristics of desquamative interstitial pneumonitis

A prospective study of eight patients with desquamative interstitial pneumonitis was performed, correlating surface ultrastructure as elucidated by scanning electron microscopy, transmission electron microscopy, viral cultures of fresh sterile lung tissue obtained at thoracotomy, and immunomicroscopy. The hypothesis that environmental pollutants may act as sensitizing agents to induce macrophage migration was pursued using high resolution elemental analysis to obtain a profile of the inorganic content of phagolysosomes in the free alveolar cell population. Four surface ultrastructural changes were observed: mild alveolar septal thickening, an apparent decrease in the number of pores of Kohn, alteration of the predominant alveolar lining population from membranous to granular pneumonocytes, and prominent intra-alveolar collections of cells with broad based ruffled projections and pseudopodia representing a macrophage population. Transmission electron microscopy corroborated these observations. Individual pneumonocyte degeneration manifested as cytoplasmic dissolution, mitochondrial swelling, chromatin disruption, and loss of lamellar bodies and endoplasmic reticulum was identified; occasionally degenerating granular pneumonocytes were displaced into the alveolar space by a supraseptal bulla containing fibrin and extracellular fluid. Viruses were not identified by ultrastructural or tissue culture techniques. High resolution elemental analysis of individual phagolysosome contents failed to reveal the presence of heavy metals or other inorganic compounds. Immune complexes were not identified by immunofluorescence microscopy. However, alveolar transeptal macrophage migration was observed by transmission electron microscopy. These observations suggest that desquamative interstitial pneumonitis represents a disease in which cellular, rather than humoral, immune processes predominate. Other nonspecific cellular immune responses under the influence of various lymphokines may be responsible for the observed morphologic alterations.

Cemented tungsten carbide pneumoconiosis

An autopsy case of cemented tungsten carbide pneumoconiosis, the first lethal case in our country, is presented. A 28-year-old woman, who had been engaged in grinding presintered metallic matrix for four years, developed respiratory symptoms. X-ray examinations were indicative of interstitial pulmonary fibrosis. Corticosteroid therapy revealed only little effect. She expired five years after the onset of the symptoms. Postmortem examination showed nonspecific interstitial pneumonitis resulting in marked lung fibrosis. Ultrastructurally, crystals were observed in cytoplasm of presumable macrophages in the fibrotic lung tissue. Electron probe microanalysis of the lung tissue showed the presence of tungsten and other constituents of tungsten carbide except for cobalt. Metal analysis demonstrated a large amount of tungsten in the lung. Cobalt was detected tenfold of the normal value in the bone. In pathogenesis of the pneumoconiosis in the cemented tungsten carbide workers, toxicity of cobalt is most suspectable, and in addition, individual susceptibility may be also important.

Desquamative interstitial pneumonitis. Cellular phase of fibrosing alveolitis

Since the original description of desquamative interstitial pneumonitis in 1967, several investigators have questioned the specificity of the disease. The concept of desquamative interstitial pneumonitis and usual fibrosing interstitial pneumonitis as two manifestations of a nonspecific disease spectrum has been proposed. Twenty-six patients with desquamative interstitial pneumonitis were evaluated with respect to clinicopathologic correlates. Biopsies were reviewed without knowledge of the patients' clinical course. The absolute histopathologic criteria for the diagnosis were (1) intra-alveolar accumulations of free alveolar cells with PAS-positive diastaseresistant cytoplasmic granules; (2) mononuclear cell interstitial inflammation; and (3) absence of necrosis, hyaline membranes, intra-alveolar fibrosis, asbestos bodies, and birefringent crystalline dust material. Transmission electron microscopic studies revealed the dominant alveolar lining cell to be the granular pneumocyte, with a prominent population of free alveolar macrophages. Patients were segregated into group 1 (cellular phase) and 2 (cicatrized phase). Although favorable short-term responses to corticosteroid therapy were observed in both groups, long-term responses were variable. Apparent complete remissions were noted in both groups.

Morphology and pathogenesis of desquamative interstitial pneumonitis

Thirty human lung biopsy specimens have been diagnoses as desquamative interstitial pneumonitis. Six cases had intraalveolar lesions, believed to be early, while 20 had advanced disease characterised by intraalveolar cellular clumps, alveolar wall fibrosis, distortion, and loss of pulmonary parenchyma. Electron microscopy, high resolution light microscopy, and cytological examination have shown that the characteristic clumps in the alveolar air spaces are formed predominantly by enlarged and aggregated macrophages. Lymphocytes and eosinophils are also present in the intraalveolar clumps and in alveolar walls. Inflammation and immunological mechanisms are suggested as causes of the cellular clumping. Interstitial pneumonitis, alveolar wall fibrosis, changes in the alveolar epithelium, and loss of lung parenchyma are believed to be secondary events.

Pulmonary changes induced by amphophilic drugs

Administration of amphophilic drugs to experimental animals causes formation of myeloid bodies in many cell types, accumulation of foamy macrophages in pulmonary alveoli, and pulmonary alveolar proteinosis. These changes are the result of an interaction between the drugs and phospholipids which leads to an alteration in physicochemical properties of the phospholipids. Impairment of the digestion of altered pulmonary secretions in phagosomes of macrophages results in accumulation of foam cells in pulmonary alveoli. Impairment of the metabolism of altered phospholipids removed by autophagy induces an accumulation of myeloid bodies. In summary, administration of amphophilic compounds causes a drug-induced lysosomal disease or generalized phospholipidosis.

Ultrastructure of pulmonary granulomatosis induced in rats by intravenous complete Freund's adjuvant

Following the intravenous injection of complete Freund's adjuvant, changes in the rat lung were studied with the electron microscope. Interstitial granulomas were produced and whereas on light microscopy these appeared to consist mainly of epitheloid cells, electron microscopy showed that the granulomas were largely made up of macrophages. Epithelioid cells were in fact few in number, atypical in appearance and limited to the periphery of some granulomas. Fenestrated capillaries were also found at the edge of the granulomas. The alveolar macrophages were increased in number and size but marked cytoplasmic vacuolation and a paucity of lysosomes are consistent with our previous suggestion that the phagocytic and migratory properties of these cells are weakened or inhibited. Alterations were found in both types of alveolar epithelial cell with the appearance of intermediate cell forms.

Desquamative interstitial pneumonia: relationship to interstitial fibrosis

Patchefsky, A. S., Israel, H. L., Hoch, W. S., and Gordon, Gloria (1973).Thorax, 28, 680-693. Desquamative interstitial pneumonia: relationship to interstitial fibrosis. The clinical course and radiographic and pathological findings in 14 patients having the histological pattern of desquamative interstitial pneumonia (DIP) have been studied. Four deaths occurred from cardiorespiratory failure and two from other diseases, and one patient has severe pulmonary insufficiency. Seven patients had altered immunological reactivity or arthritis.

Necropsy of three patients, one who died of respiratory insufficiency and two of other diseases, revealed diffuse pulmonary fibrosis with loss of the desquamative features noted on biopsy. One patient had had industrial exposure to tungsten carbide dust and x-ray diffraction analysis of the post-mortem lung showed high concentrations of this substance. Ultrastructural observation and direct immunofluorescent staining of one specimen demonstrated fibrin in the alveolar space, a feature usually regarded as distinguishing DIP from chronic fibrosing interstitial pneumonia.

Our clinical and pathological observations suggest that the histological pattern recognized as DIP may be a non-specific reaction to diverse forms of injury, which is not clearly separable from the usual type of diffuse interstitial fibrosis.

Electron microscopic studies in desquamative interstitial pneumonia associated with asbestos

A case of desquamative interstitial pneumonia (DIP) has been studied by electron microscopy in order to determine the nature of the alveolar cells. Those lining the alveolar walls proved to be granular pneumocytes (type II alveolar epithelial cells) while cells free in the lumen were alveolar macrophages. The brief literature describing the electron microscopic findings in DIP is reviewed. All workers agree that the lining cells are granular pneumocytes and most report a mixed free cell population with the emphasis shifting from desquamated epithelial cells to macrophages. In the present case asbestos bodies were also found in the lung, suggesting that DIP is not a specific disease entity.

Ultrastructural changes in the alveolar epithelium in response to Freund's adjuvant

Serial examination of the lungs of neonatal and adult rabbits treated with Freund's adjuvant demonstrated in addition to the rapid development of interstitial granulomata, marked alterations in the alveolar epithelial cells. Granular pneumonocytes became numerous and were often found adjacent to one another within a single alveolus. Their characteristic lamellar inclusions were increased in size and number, and there was often partial loss of the luminal microvilli. The membranous pneumonocytes were locally thickened, had an irregular luminal border, and on occasion, contained lamellar-like inclusions. These observations indicate that both types of epithelial cell participate in the pulmonary reaction to adjuvant, and that adjuvant-induced changes may be a useful model for studying the dynamics of the response of pulmonary epithelial cells to injury.