Diagnosis and management of alveolar proteinosis: the rôle of electron microscopy

Autoimmune Pulmonary Alveolar Proteinosis

Autoimmune pulmonary alveolar proteinosis (PAP) is a rare disease characterized by myeloid cell dysfunction, abnormal pulmonary surfactant accumulation, and innate immune deficiency. It has a prevalence of 7-10 per million; occurs in individuals of all races, geographic regions, sex, and socioeconomic status; and accounts for 90% of all patients with PAP syndrome. The most common presentation is dyspnea of insidious onset with or without cough, production of scant white and frothy sputum, and diffuse radiographic infiltrates in a previously healthy adult, but it can also occur in children as young as 3 years. Digital clubbing, fever, and hemoptysis are not typical, and the latter two indicate that intercurrent infection may be present. Low prevalence and nonspecific clinical, radiological, and laboratory findings commonly lead to misdiagnosis as pneumonia and substantially delay an accurate diagnosis. The clinical course, although variable, usually includes progressive hypoxemic respiratory insufficiency and, in some patients, secondary infections, pulmonary fibrosis, respiratory failure, and death. Two decades of research have raised autoimmune PAP from obscurity to a paradigm of molecular pathogenesis-based diagnostic and therapeutic development. Pathogenesis is driven by GM-CSF (granulocyte/macrophage colony-stimulating factor) autoantibodies, which are present at high concentrations in blood and tissues and form the basis of an accurate, commercially available diagnostic blood test with sensitivity and specificity of 100%. Although whole-lung lavage remains the first-line therapy, inhaled GM-CSF is a promising pharmacotherapeutic approach demonstrated in well-controlled trials to be safe, well tolerated, and efficacious. Research has established GM-CSF as a pulmonary regulatory molecule critical to surfactant homeostasis, alveolar stability, lung function, and host defense.

Update on Diagnosis and Treatment of Adult Pulmonary Alveolar Proteinosis

Pulmonary alveolar proteinosis (PAP) is a rare pulmonary surfactant homeostasis disorder resulting in buildup of lipo-proteinaceous material within the alveoli. PAP is classified as primary (autoimmune and hereditary), secondary, congenital and unclassifiable type based on the underlying pathogenesis. PAP has an insidious onset and can, in some cases, progress to severe respiratory failure. Diagnosis is often secured with bronchoalveolar lavage in the setting of classic imaging findings. Recent insights into genetic alterations and autoimmune mechanisms have provided newer diagnostics and treatment options. In this review, we discuss the etiopathogenesis, diagnosis and treatment options available and emerging for PAP.

Avian pulmonary proteinosis: six cases and a review of the literature

Pulmonary alveolar proteinosis (PAP) is a disease of surfactant clearance in which functional abnormalities in alveolar macrophages lead to accumulation of surfactant within alveoli in mammals. Histologic examination of 6 avian autopsies, including 4 chickens, a turkey, and a cockatiel, revealed accumulation of hypereosinophilic densely arrayed lamellar material in the lungs that was magenta by periodic acid-Schiff stain and diastase resistant. Transmission electron microscopy of the proteinaceous material in 2 cases demonstrated alternating electron-dense and electron-lucent lamellae that formed whorls and had a regular periodicity of 6-14 nm, consistent with pulmonary surfactant. Given the anatomic differences between avian and mammalian lungs, we designated the presented condition "pulmonary proteinosis," which can be observed as both an incidental finding or, when severe, may be a contributing factor to death through respiratory failure.

Alveolar Proteinosis and Phospholipidoses of the Lungs

Three pulmonary disease conditions result from the accumulation of phospholipids in the lung. These conditions are the human lung disease known as pulmonary alveolar proteinosis, the lipoproteinosis that arises in the lungs of rats during acute silicosis, and the phospholipidoses induced by numerous cationic amphiphilic therapeutic agents. In this paper, the status of phospholipid metabolism in the lungs during the process of each of these lung conditions has been reviewed and possible mechanisms for their establishment are discussed. Pulmonary alveolar proteinosis is characterized by the accumulation of tubular myelin-like multilamellated structures in the alveoli and distal airways of patients. These structures appear to be formed by a process of spontaneous assembly involving surfactant protein A and surfactant phospholipids. Structures similar to tubular myelin-like multilamellated structures can be seen in the alveoli of rats during acute silicosis and, as with the human condition, both surfactant protein A and surfactant phospholipids accumulate in the alveoli. Excessive accumulation of surfactant protein A and surfactant phospholipids in the alveoli could arise from their overproduction and hypersecretion by a subpopulation of Type II cells that are activated by silica, and possibly other agents. Phospholipidoses caused by cationic amphiphilic therapeutic agents arise as a result of their inhibition of phospholipid catabolism. Inhibition of phospholipases results in the accumulation of phospholipids in the cytoplasm of alveolar macrophages and other cells. While inhibition of phospholipases by these agents undoubtedly occurs, there are many anomalous features, such as the accumulation of extracellular phospholipids and surfactant protein A, that cannot be accounted for by this simplistic hypothesis.

Particle-induced Pulmonary Alveolar Proteinosis and Subsequent Inflammation and Fibrosis: A Toxicologic and Pathologic Review

This review analyzes the published data on cases of pulmonary alveolar proteinosis (PAP) in workers inhaling crystalline aluminum, indium, silicon, and titanium particles and possible sequelae, that is, inflammation and fibrosis, and compares these findings with those from animal experiments. In inhalation studies in rodents using crystalline indium and gallium compounds, pronounced PAP followed by inflammation and fibrosis down to very low concentration ranges have been reported. Crystalline aluminum, silicon, and titanium compounds also induced comparable pulmonary changes in animals, though at higher exposure levels. Laboratory animal species appear to react to the induction of PAP with varying degrees of sensitivity. The sensitivity of humans to environmental causes of PAP seems to be relatively low. Up to now, no cases of PAP, or other pulmonary diseases in humans, have been described for gallium compounds. However, a hazard potential can be assumed based on the results of animal studies. Specific particle properties, responsible for the induction of PAP and its sequelae, have not been identified. This review provides indications that, both in animal studies and in humans, PAP is not often recognized due to the absence of properly directed investigation or is concealed behind other forms of lung pathology.

The Clinical Clues of Pulmonary Alveolar Proteinosis: A Report of 11 Cases and Literature Review

Pulmonary alveolar proteinosis (PAP) is a rare interstitial lung disease characterized by the abnormal alveolar accumulation of surfactant components. The diagnosis of PAP can be easily missed since it is rare and lacks specific clinical symptoms. It is of great importance to have a better understanding of the crucial clue to clinically diagnose PAP and take PAP into consideration in the differential diagnosis of interstitial pulmonary diseases or other diseases with similar manifestations. Here, we analyze the clinical characteristics of 11 cases of PAP patients in local hospital and review the relevant literature in order to provide more information in diagnosis and management of PAP. In our observation, cyfra21-1 and neuron-specific enolase (NSE) known as tumor markers probably can be useful serum markers for diagnosis of PAP. As for the method of pathologic diagnosis, open-lung biopsy was the gold standard but now it is less required because findings on examination of bronchoalveolar lavage fluid (BALF) can help to make the diagnosis. We also have deep experience about when and how to carry out lung lavage.

Induced sputum deposition improves diagnostic yields of pulmonary alveolar proteinosis: A clinicopathological and methodological study of 17 cases

Pulmonary alveolar proteinosis (PAP) is a rare diffuse lung disease characterized by the accumulation of intra-alveolar lipoprotein-like surfactants. Lung core biopsy and bronchoalveolar lavage (BAL) fluid are currently the two major sources of sampling for diagnosis. In the present study, we assessed the value of induced sputum in diagnosing PAP by transmission electron microscopy and examined the PAP 2-year death rate in Asians. Transmission electron microscopy was performed on the samples from 17 patients with PAP, 13 patients with inflammatory lung diseases, and 13 healthy adults. The PAP patients were followed up for 3-156 months, and inflammatory lung diseases patients or healthy adults for 12-36 months. The ultrastructural features including diagnostic lamellar bodies of induced sputum deposition (ISD) samples were similar to that of the BAL fluid sediment. However, the rates of lamellar bodies were 73.7% in the ISD group, significantly higher than the spontaneous sputum deposition (SSD) group (42.1%, P < .0487) and similar to the BAL sediment (76.2%) and the lung biopsy (54.5%) groups. The overall 2-year death rate of our PAP patients was 17.6% (3/17), not statistically different from the healthy adults and patients with inflammatory diseases (0/13, P = .237 for both). ISD may be the preferred non-invasive sampling method for diagnosing PAP by electronic microscopy because of the higher diagnostic yield than SSD. The diagnostic yields of this noninvasive method were similar to that of lung core biopsy and BAL.

Pulmonary alveolar proteinosis secondary to Pneumocystis jiroveci infection in an infant with common variable immunodeficiency

The authors report an infant with common variable immunodeficiency (CVID) with Pneumocystis pneumonia who developed secondary pulmonary alveolar proteinosis (PAP). This is the youngest infant reported to develop PAP secondary to Pneumocystis infection in an immunocompromised state. He was effectively managed with anti-microbials, frequent lung toilet, optimized mechanical ventilation, and supportive care.

A noninvasive examination for the diagnosis of pulmonary alveolar proteinosis: induced sputum in conjunction with transmission electron microscopy

Transmission electron microscopy (TEM) of sputum deposition (SD) is an important method to assist in the diagnosis of pulmonary alveolar proteinosis (PAP). However, the low positive rate and poor quality of slices restrict the application of sputum samples in the diagnosis of PAP. Furthermore, it can be more difficult to obtain a sufficient amount of sample for TEM if the patients have little or no sputum. In this paper, we successfully diagnosed a patient with PAP using induced sputum deposition (ISD) with TEM, which is a novel and noninvasive method for PAP diagnosis. Therefore, ISD combined with TEM can be an effective method for PAP diagnosis, especially when a lung biopsy and bronchoalveolar lavage (BAL) cannot be performed, or little or no sputum can be obtained.

Transmission electron microscopy of sputum deposition in the diagnosis of pulmonary alveolar proteinosis

OBJECTIVE

To clarify the diagnostic value of sputum in pulmonary alveolar proteinosis (PAP) through transmission electron microscopy (TEM) of sputum deposition (SD).

METHODS

Eleven SD samples and 9 bronchoalveolar lavage (BAL) sediments from a PAP group including 11 patients were observed by TEM and compared with sputum direct smear, BAL cytology, and lung biopsy histopathology. Eleven healthy adults were chosen as controls.

RESULTS

The 11 sputum smears from the PAP group showed no diagnostic component, but TEM of SD revealed 7 of 11 samples had many myelin-like lamellar bodies with degeneration in the cytoplasm of macrophages, alveolar epithelial cells, and extracellular spaces, which suggested PAP. Especially, 2 patients on whom lung biopsy could not be performed and who failed to be diagnosed by BAL fluid were finally diagnosed by TEM of SD. TEM of BAL sediments showed 7 of 9 cases had diagnostic myelin-like lamellar bodies. No statistical significance was found between BAL fluid and SD by TEM. The control group didn't show diagnostic components by cytology or TEM of SD.

CONCLUSION

TEM of SD is an important noninvasive diagnostic method especially for patients against lung biopsy and BAL.

Update in nonneoplastic lung diseases

CONTEXT

Nonneoplastic lung diseases include a wide range of pathologic disorders from asthma to interstitial lung disease to pulmonary hypertension. Recent advances in our understanding of the pathophysiology of many of these disorders may ultimately impact diagnosis, therapy, and prognosis. It is important for the practicing pathologist to be aware of this new information and to understand how it impacts the diagnosis, treatment, and outcome of these diseases.

OBJECTIVE

To update current progress toward elucidating the pathophysiology of pulmonary alveolar proteinosis, idiopathic pulmonary hemosiderosis, and pulmonary arterial hypertension, as well as to present classification systems for pulmonary hypertension, asthma, and interstitial lung disease and describe how these advances relate to the current practice of pulmonary pathology.

DATA SOURCES

Published literature from PubMed (National Library of Medicine) and primary material from the authors' institution.

CONCLUSIONS

Improved understanding of the pathophysiology of pulmonary alveolar proteinosis, pulmonary hypertension, and idiopathic hemosiderosis may impact the role of the surgical pathologist. New markers of disease may need to be assessed by immunohistochemistry or molecular techniques. The classification systems for interstitial lung disease, asthma, and pulmonary hypertension are evolving, and surgical pathologists should consider the clinicopathologic context of their diagnoses of these entities.

Pulmonary alveolar proteinosis

Pulmonary alveolar proteinosis is a rare syndrome characterized by intra-alveolar accumulation of surfactant components and cellular debris, with minimal interstitial inflammation or fibrosis. The condition has a variable clinical course, from spontaneous resolution to respiratory failure and death due to disease progression or superimposed infections. The standard of care for alveolor proteinosis therapy is represented by whole lung lavage. Important discoveries have been made in the last decade with respect to disease pathogenesis and therapy of both congenital and acquired forms of the disease. Granulocyte-macrophage colony-stimulating factor (GM-CSF) pathway has been shown to be involved in the disease pathogenesis of both acquired and congenital disease. Furthermore, anti-GM-CSF blocking autoantibodies have been found in the serum and bronchoalveolar lavage fluid and seem to interfere with the surfactant clearance by alveolar macrophages in many acquired cases. In the congenital form, the most common defects identified to date are several mutations of the genes encoding GM-CSF receptor subunits or surfactant proteins. Using GM-CSF as a therapeutic tool has also been shown to be effective in at least half of the acquired cases treated, while the importance of quantitative determination of anti-GM-CSF antibodies before and during the course of the therapy, as well as the autoantibody titer-GM-CSF dose relationship are to be elucidated. The congenital form of the disease does not respond to therapy with GM-CSF, consistent with the known primary defects and differences in disease pathogenesis.

Pulmonary Alveolar Proteinosis

Pulmonary alveolar proteinosis (PAP) is characterized by the accumulation of surfactant phospholipids and proteins within the lung alveoli. Important advances have been made over the past 8 years in our understanding of this disease, offering new directions for research and patient care. First, genetically altered mice that are homozygous for a disrupted granulocyte-macrophage colony-stimulating factor (GM-CSF) gene developed a lung lesion with histologic resemblance to PAP. The surfactant is thought to be catabolized or cleared mostly by alveolar macrophages, this process being dependent on GM-CSF. Second, a neutralizing autoantibody against GM-CSF was found in serum and bronchoalveolar lavage fluid of patients with idiopathic PAP but not in healthy controls, thereby raising the suspicion that human PAP may be an autoimmune disease. The relationship between the antibody and disease pathogenesis remains unclear but data suggest that the GM-CSF antibody may have a potential role as a diagnostic test. No specific therapy exists for PAP. Sequential whole lung lavage is the standard of care. Exogenous therapy with GM-CSF may improve the lung disease in some patients with PAP but this therapy is still experimental. Interventions directed at treating a relative GM-CSF deficiency by administration of GM-CSF or lowering the antibody level (i.e. by plasmapheresis or immunosuppression) may hold promise as future therapy for this rare disease.

Pulmonary alveolar proteinosis: progress in the first 44 years

Pulmonary alveolar proteinosis is a rare clinical syndrome that was first described in 1958. Subsequently, over 240 case reports and small series have described at least 410 cases in the literature. Characterized by the alveolar accumulation of surfactant components with minimal interstitial inflammation or fibrosis, pulmonary alveolar proteinosis has a variable clinical course ranging from spontaneous resolution to death with pneumonia or respiratory failure. The most effective proven treatment--whole lung lavage--was described soon after the first recognition of this disease. In the last 8 years, there has been rapid progress toward elucidation of the molecular mechanisms underlying both the congenital and acquired forms of pulmonary alveolar proteinosis, following serendipitous discoveries in gene-targeted mice lacking granulocyte-macrophage colony-stimulating factor (GM-CSF). Impairment of surfactant clearance by alveolar macrophages as a result of inhibition of the action of GM-CSF by blocking autoantibodies may underlie many acquired cases, whereas congenital disease is most commonly attributable to mutations in surfactant protein genes but may also be caused by GM-CSF receptor defects. Therapy with GM-CSF has shown promise in approximately half of those acquired cases treated, but it is unsuccessful in congenital forms of the disease, consistent with the known differences in disease pathogenesis.

Pulmonary alveolar proteinosis: a spectrum of cytologic, histochemical, and ultrastructural findings in bronchoalveolar lavage fluid

Pulmonary alveolar proteinosis (PAP) is defined as abundant extracellular proteinaceous periodic acid-Schiff (PAS)-positive material which represents surfactant distending alveolar spaces. While this lesion is defined by histologic findings, there are characteristic radiologic features and cytologic findings in bronchoalveolar lavage (BAL) specimens that together may provide a confident diagnosis. The BAL specimens from all patients for which a diagnosis of PAP was made or suggested on either cytologic or biopsy specimens at University of North Carolina Hospitals from 1990-1999 were reviewed. There were 23 cytologic specimens from 11 patients. Patient ages ranged from 6 wk to 76 yr. All 23 specimens had slides prepared for Papanicolaou stain, 22 specimens (all patients) had Diff-Quik stains, 10 specimens (6 patients) had PAS stains, and 8 specimens (5 patients) had lipid stains. Nine patients had lung biopsies in addition to cytologic specimens. The clinical charts of all patients were reviewed. Twenty-one cytologic specimens were described as cloudy or milky, and 2 were bloody. By chart review and/or biopsy results, 8 patients were felt to have definite PAP. The initial lavage specimens from 6 of these patients showed classic cytologic findings of PAP, consisting of paucicellular specimens dominated by adundant extracellular granular to globular material which was basophilic on Diff-Quik stain, pale to focally eosinophilic on Pap stain, and PAS-positive, diastase-resistant. Five of these patients had biopsies; 3 showed PAP, and 2 were insufficient. Later BAL specimens after therapeutic lavage from these patients were often less characteristic, with scant extracellular material present. The other 2 patients with PAP clinically and by biopsy had atypical cytologic findings, with one showing numerous macrophages with scant PAS-positive material and abundant lipid mimicking lipid pneumonia, and one showing moderate eosinophils in addition to the extracellular proteinacous material. The remaining 3 patients were felt not to have PAP clinically or by biopsy (1 lymphocytic interstitial pneumonitis, 1 rheumatoid lung, and 1 hemosiderosis), and their BAL specimens predominantly contained macrophages with rare proteinaceous extracellular globules. Electron microscopy was performed in 5 patients (4 considered to have PAP, and 1 with lymphocytic interstitial pneumonitis) and in all cases showed whorled myelin figures characteristic of surfactant. The PAP cases and the non-PAP case had identical ultrastructural findings. We conclude that BAL specimens with classic cytologic features and supporting clinical and radiographic evidence may be diagnosed as PAP. Atypical specimens should be approached with caution, and may represent either PAP or other pulmonary diseases with secondary accumulation of surfactant. Cytology specimens taken subsequent to therapeutic lavage from PAP patients may also not be diagnostic.

Secondary alveolar proteinosis in cancer patients

Pulmonary alveolar proteinosis (AP) is a rare cause of progressive respiratory failure in the normal host. It was first described by Rosen and coworkers in 1958 on the morphological basis of the accumulation of a PAS-positive material in the alveolar space. A couple of years later, AP was found to be unexpectedly associated with malignant diseases, especially with acute or chronic myeloid leukemias. These forms were called secondary AP in opposition to the primary forms observed in normal hosts. Probably because of its morphological definition and late diagnosis by means of histology or autopsy material, secondary AP has been considered to be life-threatening for a long time. However, recent observations show that AP can be diagnosed early in the course of the disease, especially through bronchoalveolar lavage, as long as the pathologist is aware of this possibility. Another point is that secondary AP can be reversible, both clinically and morphologically. This article summarizes the clinical features, morphological findings, and the main malignant diseases associated with secondary AP. We also comment on the hypotheses proposed in the literature to explain the association of AP, malignant disease, and immunosuppression. Alveolar macrophage is likely a key factor in the occurrence of secondary AP.

Pulmonary alveolar proteinosis. A spontaneous and inducible disease in immunodeficient germ-free mice

Spontaneous pulmonary alveolar proteinosis (PAP), which resembles human PAP, was found in aging (35 to 40 weeks) germ-free SCID-beige (scid/scid-bg/bg) mice. Spontaneous PAP was not observed in germ-free SCID mice. We describe the induction of PAP in SCID mice monoassociated with a pure culture of Candida albicans for 15 to 40 weeks. The gastrointestinal tracts only are colonized, and disseminated or pulmonary candidiasis does not occur. Another spontaneous form of PAP, designated type II, was discovered in germ-free beige (bg/bg and bg/+) mice and in beige-nude (bg/bg-nu/nu) mice. In this form of PAP, macrophages appear to be unable to digest the ingested phospholipoprotein complex and then accumulate in the alveolar spaces. These murine models should prove useful in elucidating the relationships between immune deficiencies, infections, and cytokine regulation of granulocyte and macrophage production and function in pulmonary alveolar proteinosis.

Electron microscopy what Izzits revisited: an ultrapath VI quiz

Thirteen cases of various natures, selected from a collection shown and discussed at Ultrapath VI, are presented in quiz format for recognition or diagnosis.

Coexisting endogenous lipoid pneumonia, cholesterol granulomas, and pulmonary alveolar proteinosis in a pediatric population: a clinical, radiographic, and pathologic correlation

Benign pulmonary diseases that have been associated with the accumulation of endogenous lipids within the alveoli, bronchioles, and interstitial tissues include endogenous lipoid pneumonia (ELP), pulmonary alveolar proteinosis (PAP), pulmonary interstitial and intra-alveolar cholesterol granulomas (PICG), various xanthomatous lesions, and malakoplakia. In ELP, fat-filled finely vacuolated macrophages fill the alveoli. In PAP, the aveoli become filled with cholesterol and periodic acid-Schiff (PAS)-positive acellular debris. In PICG, cholesterol esters are released from degenerating macrophages and, as organization occurs, the cholesterol is deposited in the form of acicular clefts within the interstitium. These morphologically distinct presentations of endogenous lipid deposition within the lung have long been thought to represent unique disease processes but several authors now postulate a possible relationship between these entities. We report here on the clinical, radiographic, and morphologic findings in eight pediatric patients with diverse primary disease processes who were subsequently found to have varying and often coexisting degrees of ELP, PAP, and PICG.

Ultrastructural analysis of pulmonary alveolar proteinosis induced by methylnaphthalene in mice

Pulmonary alveolar proteinosis was induced at a 100% incidence in B6C3F1 female mice by twice weekly painting the back skin with methylnaphthalene for 30 weeks to give a total dose of 7.14 g/kg b.wt. Semithin sections were used for defining areas of type II pneumocyte hyperplasia and hypertrophy and associated proteinosis. Ultrastructurally, alveolar spaces were found to be filled with numerous myelinoid structures resembling the lamellar bodies of type II pneumocytes. Mononucleated giant cells (balloon cells, BC) containing numerous myelinoid structures, lipid droplets and many electron dense amorphous ascicular crystals were closely associated with this extracellular membranous material. Stacks of elastic fibers stained with tannic acid and bundles of collagen fibers were loose and discontinuous in the interstitium of affected areas. The following pathogenesis is hypothesized: type II pneumocytes produce increased amounts of lamellar bodies due to their hyperplasia and hypertrophy and develop to form BC which liberate numerous myelinoid structures on their rupture. Epidermal absorption of methylnaphthalene is an efficient reliable method of induction of this internal disease.

Pulmonary alveolar proteinosis associated with Pneumocystis carinii. Ultrastructural identification in bronchoalveolar lavage in AIDS and immunocompromised non-AIDS patients

Pneumocystis carinii (PC) has been recognized as frequently responsible for most opportunistic pulmonary infections occurring in immunocompromised AIDS and non-AIDS patients. Moreover, these patients can be considered at risk for secondary pulmonary alveolar proteinosis. Therefore, we have investigated the occurrence of associated secondary alveolar proteinosis and PC pneumonitis in AIDS and non-AIDS immunocompromised patients. In a series of 26 bronchoalveolar lavages (BAL) in patients with PC pneumonitis (19 AIDS and seven non-AIDS patients), we observed on light microscopy, in addition to the honeycombed material, areas of an extracellular material that had a different pattern which was suggestive of that described in alveolar proteinosis. A systematic ultrastructural study of these 26 BAL fluid samples demonstrated in each of them an accumulation of phospholipid surfactantlike extracellular material mixed or not with the PC cysts. In nine cases, the observation of lipoproteinaceous material on light microscopy and abundant phospholipid material with myelinlike and myelin tubular laminated structures on electron microscopy was highly suggestive of an associated pulmonary alveolar proteinosis (PAP). Such an accumulation of extracellular material was not observed in the 11 BAL fluid samples collected in immunocompromised patients (seven AIDS and four non-AIDS patients) without PC pneumonitis. These findings demonstrated a particular frequency of associated PAP with PC pneumonitis. These results raise important questions concerning (1) the consequence of such an alveolar accumulation of lipoproteinaceous material on the clinical status and prognosis of the pneumonitis, and (2) the mechanisms responsible for this accumulation.

Approach to the patient with diffuse lung disease

When evaluating diffuse lung infiltrates, the clinician should place special emphasis on the acuity of symptoms, nonpulmonary complaints and findings, environmental exposures, and risk factors for immunosuppressive diseases. Certain radiographic features, such as the distribution of opacities, hilar adenopathy, Kerley-B lines or pneumothorax, or pulmonary function tests demonstrating air flow limitation also narrow the differential diagnosis. One can direct the subsequent workup based on the narrowed differential diagnosis, the pace of disease, the activity of the ongoing inflammatory-immune process, and the age, overall medical condition, and wishes of the patient. Unless a specific diagnosis (for example, hypersensitivity pneumonitis, the treatment of which is withdrawal of the offending agent) can be made, therapy of noninfectious diffuse lung disease is quite unsatisfactory. Immunosuppressive therapy is indicated to arrest the active inflammatory process with the hope that objective signs of improvement will occur after a 3- to 12-month course. Important areas of basic research in pulmonary fibrosis include cell-cell and cell-matrix interactions in the lung interstitium and delineation of fibroblast biology and cytokine-mediated lung connective tissue pathology. More successful therapies will probably evolve from better understanding of the molecular and cellular biology of the lung fibrogenic process.

Sandblaster's lung with mycobacterial infection

This report describes the development of alveolar silico-lipoproteinosis complicated by Mycobacterium kansasii infection in a previously healthy man who worked as a sandblaster. Alveolar silico-lipoproteinosis is a rare disease that usually is fatal within 1 year of onset of symptoms. There is a high incidence of mycobacterial infection, half being caused by atypical organisms.

Pulmonary alveolar phospholipoproteinosis: experience with 34 cases and a review

A retrospective review of Mayo Clinic records through 1983 revealed 84 patients (24 male and 10 female; mean age, 41 years) with the diagnosis of pulmonary alveolar phospholipoproteinosis. The major clinical features were dyspnea, cough, fever, and chest pain. Chest roentgenograms usually showed bilateral symmetric alveolar infiltrates, but asymmetric, unilateral, and chronic patchy patterns were also noted. Diagnosis was established by thoracotomy-lung biopsy in 26 patients. Histologic analysis revealed uniform filling of the alveoli by periodic acid-Schiff-positive material and maintenance of normal alveolar architecture. Electron microscopy showed enlarged alveolar macrophages with lamellar osmiophilic inclusions, dense granules, and myeloid bodies. Of the 21 patients who underwent therapeutic bronchoalveolar lavage, 13 had no recurrence of the disease during a mean follow-up of 8.8 years. In patients who underwent pulmonary function testing both before and after lavage, significant restrictive dysfunctions present before the procedure were alleviated afterward. Three deaths occurred among the 34 patients. Pulmonary alveolar phospholipoproteinosis may result from defective clearance of phospholipids by the alveolar macrophages, excessive production of phospholipids by type II pneumocytes, or both. It is likely a nonspecific response to a variety of injuries to the alveolar macrophage or type II pneumocyte or both, including exposure to certain dusts and chemicals and occurrence of hematologic diseases or infections. The uncommon occurrence of this disorder suggests individual susceptibility.

Lung response to particulates with emphasis on asbestos and other fibrous dusts

Many theories have been proposed to explain asbestosis and asbestos-related pulmonary disease. However, none of the theories give a completely plausible explanation for the pathogenesis. Recently, attention has been drawn to a theory that the fibrogenicity or carcinogenicity of fibrous dust particles is related to fiber diameter and length rather than to chemical properties. This theory may help partially elucidate the disease process but is still far from solving the enigma of pulmonary fibrosis or carcinogenesis. The theory cannot explain the absence of these pathological effects among fiberglass workers or experimental animals exposed by inhalation (even though mesotheliomas are induced by intrapleural implantation and fiber dimension-related fibrogenicity is demonstrated by intratracheal injection). Little information regarding the pulmonary response to manmade fibrous particles is available in animals following inhalation exposure. Attempts should be made to confirm the absence of adverse effects using animal inhalation experiments even though to this point there is no conclusive evidence that either lung cancer or pulmonary diseases can be produced among employees in manmade fiber industries. A new research trend seems concentrated on testing the durability of asbestos or manmade fibers. This is based on the concept that biological effects of fibrous particles are the result of relative durability and that particles which can be fragmented or shortened may be less pathogenic. In the last two decades, considerable understanding about pulmonary fibrosis and carcinogenesis of asbestos has been achieved by clinical and animal experiments. In vitro tests including cytotoxicity, hemolysis, immunology, and enzyme biochemistry have provided important information on the interrelationships among these various biological effects of asbestos.

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.

Computed tomographic appearance of pulmonary alveolar proteinosis in adults

Two cases of adult pulmonary alveolar proteinosis are presented with emphasis on the computed tomographic findings in both cases. Each patient demonstrated a pattern of diffusely increased lung density on both standard radiographic and computed tomographic examinations of the lung. There was no evidence of adenopathy, pleural effusion, or cardiomegaly in either patient. The diagnosis of pulmonary alveolar proteinosis was established in both patients by open lung biopsy. The optical microscopy and electron microscopy examinations of the biopsy material in each instance demonstrated marked filling of the alveoli with periodic-acid-Schiff-positive material and intraalveolar lamellar bodies. The diagnosis of sarcoid was entertained prior to the open lung biopsy in one patient, a young adult black male. Although the computed tomographic appearance was similar in each case and of no value in the diagnosis of pulmonary alveolar proteinosis, it was helpful in assessing the extent of the disease within the lung.

Applications of electron microscopy to diagnostic pulmonary pathology

Viruses and other possible causative agents should be sought light and electron microscopically in all cases of ill-defined diseases including "sarcoid." Ideally, tissue should be prepared for electron microscopic examination as soon as a specimen is obtained; however, when this has not been done, tissue preserved in formalin solution can be used. Viruses, some bacteria, and other agents suspected on the basis of light microscopic findings can be verified electron microscopically by reprocessing paraffin-embedded tissue from areas that show smudge cells, focal necrosis with atypical cellular proliferation, and nuclear inclusions. Electron microscopically, all dying cells show swelling and rupture of cellular organelles and membranes; reactive changes include proliferation of branching tubules and paracrystalline and other types of proteinaceous precipitates (inclusions) in both the nucleus and cytoplasm. Qualitative and quantitative changes of cellular organelles, fibrils, microvilli, and intercellular junctions reflect hyperplasia, metaplasia, or dysplasia of the cell and may enable identification of the diseases, e.g., desquamative interstitial pneumonia. In various conditions, basal laminae become irregular, disruptive, or reduplicated following epithelial necrosis and regeneration. Electron microscopic evidence of immunologic damage to basal lamina and cells and immuno-electron-microscopic features of the lung in general require further studies. Electron microscopic features of transbronchial biopsy specimens may be diagnostic in cases of alveolar proteinosis, histiocytosis X, and amyloidosis. Ultrastructural abnormalities of cilia are common; primary ciliary defects are rare. Finally, light microscopic, scanning electron microscopic, and x-ray energy-dispersive spectrometric examinations of paraffin-embedded sections appear most practical for the pathologic evaluation of cases of pneumoconiosis.

Alveolar proteinosis: diagnosis and treatment over a 10-year period

Ten years' experience of using bronchoalveolar lavage in the treatment of 10 patients with alveolar proteinosis is reported. The diagnosis was often missed. The interval between onset of symptoms and diagnosis varied from six weeks to six years (median 2 years), so that the start of treatment was often delayed. Some patients experienced severe progressive disability before they had treatment. Whole-lung lavage proved to be a safe, repeatable procedure which provided symptomatic, physiological, and radiological improvement and allowed all 10 patients treated to return to full-time employment.

Pulmonary alveolar proteinosis. Staining for surfactant apoprotein in alveolar proteinosis and in conditions simulating it

Formalin fixed paraffin-embedded lung tissues (n = 13) or lavage material (n = 4) from 17 patients in whom alveolar proteinosis was the primary disease and ten patients with other primary diagnoses but lung morphology similar to alveolar proteinosis were examined. The tissues were stained by the periodic acid-Schiff method and by the immunoperoxidase method for surfactant specific apoprotein. The intra-alveolar material in patients with primary alveolar proteinosis stained uniformly for surfactant specific apoprotein, whereas the staining was focal in patients with other primary diseases associated with intra-alveolar accumulation of proteinacious material. In both situations, the number of inflammatory cells, especially macrophages, was small. These observations extend an earlier impression about the presence of surfactant specific apoprotein in alveolar spaces in patients with primary alveolar proteinosis and provide a distinction between primary alveolar proteinosis and morphologically similar appearance due to other causes, ie, secondary alveolar proteinosis. The lack of macrophages in the affected tissue appears to be the major pathogenetic factor in alveolar proteinosis.

Technical aspects of bronchopulmonary lavage for alveolar proteinosis: two case reports

Under general anaesthesia, therapeutic bronchopulmonary lavage was performed in two patients suffering from alveolar proteinosis. In one patient, difficulties were experienced during attempted lavage of the right lung. Fluid trapping occurred when saline was infused down the tracheal (right) lumen of a Carlen's double lumen endobronchial tube and also when a left Robertshaw tube was similarly used. Spillover of saline into the left lung occurred when a right Robertshaw was used. Efficient lavage of the right lung could only be performed after insertion of a White endobronchial tube. In the second patient, both lungs were washed without problem using a left Robertshaw tube after difficulty had been experienced with a Carlen's tube. In both cases venous admixture was least when the lavaged lung was filled with saline. Hypoxaemia increased as the lung was drained. Details of technique are discussed as are problems with double lumen endobronchial tubes used during the procedure.

Surfactant apoprotein in nonmalignant pulmonary disorders

Formalin-fixed, paraffin-embedded lungs exhibiting a variety of nonmalignant disorders were studied by immunoperoxidase staining using antibodies specific for surfactant apoprotein, IgG, IgM, IgA, albumin, fibrinogen, and lysozyme. Normal Type II pneumocytes showed staining for surfactant apoprotein in the perinuclear region only. The extent and intensity of staining for apoprotein was markedly increased in reactive Type II pneumocytes. This increase appeared to be a nonspecific reaction to lung injury. The intra-alveolar material in pulmonary alveolar proteinosis stained intensely for surfactant apoprotein, indicating that the accumulated proteinaceous material contained pulmonary surfactant. Type II pneumocytes in pulmonary alveolar proteinosis exhibited hyperplasia as well as hypertrophy. The few macrophages in lung affected by pulmonary alveolar proteinosis stained intensely for lysozyme. The excessive intraalveolar accumulation of proteinaceous material in pulmonary alveolar proteinosis may be the result of both an over-production as well as a deficient removal of pulmonary surfactant.

Degenerative processes in the pathogenesis of pulmonary alveolar lipoproteinosis

Electron microscopy in an infant of 4 months with pulmonary alveolar lipoproteinosis showed filling of the alveoli with osmiophilic lamellar bodies. Similar structures were present in the cytoplasm of type I alveolar epithelial cells and to a lesser extent in the capillary endothelium and interstitium. These changes represent widespread degenerative processes in the lung caused by an unidentified cytotoxic agent. In this patient the disease is comparable to the drug-induced cytotoxic animal model and differs from the dust-induced hypersecretory animal model.