Asbestos exposure in buildings.

Asbestos-related diseases are dose-related. Among these, asbestosis has occurred only with the heavy exposures of the past, is a disappearing disease, and is of no concern with the very small exposures from building occupancy. A possibly increased incidence of lung cancer has been included in risk analysis, but probably is also related to high exposure in that both epidemiologic and experimental data suggest a link between the process of alveolar inflammation and fibrogenesis and carcinogenesis. The major concern has been mesothelioma in that it has occurred with much lower household and neighborhood exposure. Additionally, anxiety concerning buildings with ACM has been heightened by finding of friable asbestos in about 20% of public buildings, discovery of environmental asbestos fibers and asbestos bodies in autopsies, and demonstration of a linear relationship between exposure and lung cancer risk in occupational groups, inviting extrapolation to a much lower dose. Legislative and regulatory mandates, promotional activities of abatement companies, adverse court decisions placing the onus of repairs on asbestos manufacturers, and a "pandemic of mediagenic disease" all have contributed to panic among building owners, school boards, insurers, and others. In that there is neither clinical nor epidemiologic support for asbestos-related disease from building occupancy, risk estimates have been based on extrapolation from past experience with generally high-dose occupational exposure. However, only a few epidemiologic studies have contained quantitative estimates of exposure, and these have been measured in terms of all particles, with conversion to asbestos fibers uncertain and the fiber type and dimension largely unknown. To these uncertainties must be added the unproved assumption of a linear dose-response down to very low levels of exposure with no threshold. At the other end of the scale extrapolation has required measurements of present building exposure, and these have been revised downward as methods for collection and analysis have improved. Risk estimates in this country and abroad have assumed exposure to 0.001 f/mL, with indicated lifetime risks for cancer ranging from about 2 to 20 per 1 million students. However, these estimates have assumed mixed fiber exposure whereas most building exposure comes from chrysotile, which is much less toxic than the amphiboles.(ABSTRACT TRUNCATED AT 400 WORDS)

Idiopathic pulmonary fibrosis in asbestos-exposed workers.

Diffuse interstitial lung disease in asbestos-exposed workers is presumed to represent asbestosis. Among 176 asbestos-exposed persons for whom lung tissue was available, we found nine with clinical features consistent with asbestosis, but histologic sections failed to demonstrate asbestos bodies, the usual requirement for pathologic diagnosis of asbestosis (Group I). These nine were compared by analytic electron microscopy with nine persons with idiopathic pulmonary fibrosis (Group II), and with nine persons with all the criteria of asbestosis (Group III). The three groups did not differ significantly with respect to lung burden of chrysotile or tremolite and actinolite, but Group III had a lung burden of amosite and crocidolite that was three orders of magnitude greater than in Groups I and II, with no overlap. We conclude that (1) the American Thoracic Society criterion of "a reliable history of exposure" is sometimes difficult to define; (2) asbestos bodies are seen in tissue sections only when exposure has been reasonably high, and given the proper clinical setting, the presence of diffuse fibrosis and asbestos bodies in tissue sections are sensitive and specific criteria for a diagnosis of asbestosis; and (3) the prevalence here of 5.1% nonasbestos-induced interstitial lung disease among asbestos-exposed persons is artefactually high because of atypical case selection. However, because asbestosis is a disappearing disease, such cases will become more frequent. The identification of these other diseases is important because therapy and prognosis may differ from that of asbestosis.

Pulmonary fibrosis in aluminum oxide workers. Investigation of nine workers, with pathologic examination and microanalysis in three of them.

Epidemiologic surveys have indicated an excess of nonmalignant respiratory disease in workers exposed to aluminum oxide (Al2O3) during abrasives production. However, clinical, roentgenographic, histologic, and microanalytic description of these workers are lacking. This is a report of nine Al2O3-exposed workers with abnormal chest roentgenograms (profusion greater than or equal to 1/0, ILO/UC) from a plant engaged in the production of Al2O3 abrasives from alundum ore. Mean duration of exposure was 25 yr, and time since first exposure was 28 yr. in a subgroup of three, the severity of symptoms, reduction in the forced vital capacity (67% predicted) and diffusing capacity (51% predicted), and progressive roentgenographic changes (profusion greater than or equal to 2/2) prompted open lung biopsy. Lung tissue was analyzed by scanning electron microscopy and electron microprobe analysis. In each of the three biopsies, interstitial fibrosis with honeycombing was seen on routine section. In one biopsy, silica and asbestos fiber counts were at the low end of the range seen with silicosis and asbestosis; however, the absence of asbestos bodies and silicotic nodules suggested that the fibrosis was due to another cause. Metals occurred in amounts several orders of magnitude above background, and the majority was aluminum as Al2O3 and aluminum alloys. The findings in these nine workers suggests a common exposure as the possible cause. The nonspecific pathologic findings, absence of asbestos bodies and silicotic nodules, and the striking number of aluminum-containing particles suggest that Al2O3 is that common exposure. The possibility of "mixed dust" fibrosis should also be considered.

Multiple cystic fibrohistiocytic tumors of the lung: report of two cases.

We describe two adults with multiple cystic fibrohistiocytic tumors of the lung that manifested as bilateral nodular opacities, cystic lesions, or both on chest roentgenograms. One patient had recurrent episodes of pneumothorax and intermittent shortness of breath; the other was asymptomatic. Open-lung biopsy specimens showed identical histologically benign fibrohistiocytic proliferations associated with formation of cysts that were lined by metaplastic bronchiolar, squamous, or type II alveolar epithelium and old hemorrhage in the cysts. In both patients, the lesions grew slowly over a period of years. These unusual multiple bilateral fibrohistiocytic tumors of the lung should be included in the differential diagnosis of bilateral cystic lesions in the lung.

Respiratory bronchiolitis-associated interstitial lung disease and its relationship to desquamative interstitial pneumonia.

Respiratory bronchiolitis is a mild inflammatory reaction commonly noted in asymptomatic cigarette smokers. We reviewed 18 cases of respiratory bronchiolitis-associated interstitial lung disease (RB/ILD), which had been diagnosed on the basis of clinical evaluation and open-lung biopsy. All patients were cigarette smokers. The sex distribution of the patients was approximately equal, and their mean age was 36 years. Chest roentgenograms showed reticular or reticulonodular infiltrates in 72% of the patients. Histologically, inflammation of the respiratory bronchioles, filling of the bronchiolar lumens and surrounding alveoli with finely pigmented macrophages, associated interstitial inflammation, and mild fibrosis were noted. In most patients, respiratory improvement ensued when they stopped smoking. Because of histologic similarities to desquamative interstitial pneumonia (DIP), the 18 cases of RB/ILD were compared with 36 cases of DIP. DIP tended to occur in older persons, caused more severe symptoms, displayed ground glass infiltrates on chest roentgenograms, was characterized by more severe interstitial disease on pulmonary function tests, and was often associated with progressive respiratory disease.

Asbestos-associated diseases in a cohort of cigarette-filter workers.

To estimate the effects on health of occupational exposure to crocidolite, a highly toxic form of asbestos, we studied a cohort of 33 men who worked in 1953 in a Massachusetts factory that manufactured cigarette filters containing crocidolite fibers from 1951 to 1957. Twenty-eight of the men have died, as compared with 8.3 deaths expected. This increased mortality was attributable to asbestos-associated diseases. Fifteen deaths were caused by cancer, as compared with 1.8 expected (relative risk, 8.2; 95 percent confidence interval, 4.6 to 13.4), including eight from lung cancer, five from malignant mesothelioma, and two from other types of cancer. There were seven deaths from nonmalignant respiratory disease, as compared with 0.5 expected (relative risk, 14.7; 95 percent confidence interval, 5.9 to 30.3), of which five were due primarily to asbestosis. In contrast, the mortality rates from cardiovascular diseases and all other causes were not increased. Four of the five living workers have pulmonary asbestosis; three of them have recently diagnosed cancers, including two additional lung cancers. We conclude that the extremely high morbidity and mortality in these workers were caused by intense exposure to crocidolite asbestos fibers.

Chronic eosinophilic pneumonia. A report of 19 cases and a review of the literature.

Clinical, roentgenographic and pathologic findings in patients with chronic eosinophilic pneumonia, including 19 additional cases, have been reviewed and summarized. Most patients present with subacute respiratory and constitutional symptoms and have failed to respond to therapy for presumptive pneumonia. A previous history of atopy, most often asthma, will be obtained in one-half. Eosinophilia occurs in most cases and its absence may be the major indication for lung biopsy. Although pulmonary infiltrates are more often peripheral than not, the classic "photographic negative of pulmonary edema" is seen in less than one-third of cases. Pathologic findings include an intra-alveolar and interstitial infiltrate which comprises eosinophils, histiocytes, and exudate. Bronchiolitis obliterans and eosinophilic microabscesses occur less frequently. Open-lung biopsy is preferable when atypical features prevent a confident clinical diagnosis. The exquisite responsiveness of CEP to corticosteroids should encourage use of a therapeutic trial when there is a strong clinical suspicion of the disorder. The rapid clinical response should not deter the clinician from giving a prolonged course of treatment. The differential diagnosis includes other diseases characterized by PIE and the more recently recognized bronchiolitis obliterans and organizing pneumonia, a disorder which is also marked by peripheral pulmonary infiltrates.

Congenital bronchial atresia. A report of 4 cases and a review of the literature.

The clinical, radiographic, and pathologic findings in 82 patients with congenital bronchial atresia (CBA) have been reviewed, and we have discussed 4 additional cases. Most patients are asymptomatic and come to attention because of abnormal radiographic findings of a round or lobulated perihilar, solid, or cystic mass--the mucoid impaction sign. Typically, the region distal to the mass is hyperinflated. Recently, computed tomography has been shown to be diagnostic and its use obviates the need for other more complex imaging modalities or surgical exploration. Excisional surgery has been performed to preserve lung function in younger patients, because of lack of familiarity with the entity or, as in 2 of our cases, to prevent recurrent infections. Pathologic findings include a cystic, blindly terminating, mucus-filled bronchocele without connection to the main bronchial tree, but with normal subsequent generations of bronchi. Distally there is noncollapsible hyperinflation of the corresponding lung segment or lobe as the result of collateral ventilation from the surrounding lung. The anomaly is the result of an insult to the growing bronchial tree in early development. The differential diagnosis most often includes allergic bronchopulmonary aspergillosis, but cystic bronchiectasis, bronchogenic cysts, and intrapulmonary sequestration should also be considered. Unusual features in our 4 cases included recurrent pulmonary infections in 2 patients and thoracic cage asymmetry in 1.

Patient work-up for bullectomy.

A localized area of hypertransradiance often leads to surgical referral. Among 608 cases, 115 were due to local lesions of airways, blood vessels, or parenchyma. Among the remaining 493 with bullae from diffuse emphysema, 21% underwent surgery. Good restoration of function occurred in patients with rapidly progressive dyspnea who did not have a bronchitic component, recurrent infections, or CO2 retention. Physiologically, preoperative findings suggestive of tension pneumothorax, including severe restriction, marked air trapping, and little ventilation/perfusion mismatch suggested good results. Favorable radiographic findings included well-defined, large air spaces without stigmata of diffuse emphysema, serial films showing rapid enlargement of bullae, and expiration films with good thoracic motion and obscuration of lung around bullae. Compressed but otherwise intact lung was best demonstrated by angiography and CT scans. Palliative bullectomy in severe diffuse emphysema sometimes had gratifying clinical results. Resection of small bullae never caused improvement. Localized giant bullae most often were associated with paraseptal or periacinar emphysema, and the best surgical results were obtained in this group.

Thoracic surgical problems in asbestos-related disorders.

Among 1,577 persons with asbestos exposure followed up from 3 to 30 years, 113 had thoracic surgical procedures for asbestos-related disorders. Twenty-six individuals suspected of having asbestosis with atypical features underwent open-lung biopsy; a different disease was revealed in 14. Most of the 29 patients with mesothelioma had a small thoracotomy for diagnosis only; chemotherapy in half of them proved entirely ineffective. Experience with 23 patients with bronchogenic carcinoma did not differ from that in persons not exposed to asbestos. Problems of causal relationship are discussed. Most of the 68 individuals with benign asbestos pleural effusion had no symptoms, but because of recurrence, 15 were operated on for decortication or for possible mesothelioma. Hyaline plaques often were mistaken for lung, rib, or diaphragmatic tumors, and sometimes mesothelioma was suspected. Operative intervention in the 24 patients with plaques could have been avoided by obtaining a more detailed occupational history and reviewing previous chest roentgenograms, which invariably showed identical or smaller plaques from 2 to 17 years earlier.

Bronchiolitis obliterans organizing pneumonia.

In 50 of 94 patients with bronchiolitis obliterans we found no apparent cause or associated disease, and the bronchiolitis obliterans occurred with patchy organizing pneumonia. Histologic characteristics included polypoid masses of granulation tissue in lumens of small airways, alveolar ducts, and some alveoli. The fibrosis was uniform in age, suggesting that all repair had begun at the same time. The distribution was patchy, with preservation of background architecture. Clinically, there was cough or flu-like illness for 4 to 10 weeks, and crackles were heard in the lungs of 68 per cent of the patients. Radiographs showed an unusual pattern of patchy densities with a "ground glass" appearance in 81 per cent. Physiologically, there was restriction in 72 per cent of the patients, and 86 per cent had impaired diffusing capacity. Obstruction was limited to smokers. The mean follow-up period was four years. With corticosteroids, there was complete clinical and physiologic recovery in 65 per cent of the subjects; two died from progressive disease. This disorder differs from bronchiolitis obliterans with irreversible obstruction. It was confused most often with idiopathic pulmonary fibrosis. In view of the benign course and therapeutic response, a histologic distinction is important.

Diffuse pleural thickening in an asbestos-exposed population: prevalence and causes.

Two types of pleural reaction have been described in association with asbestos exposure: pleural plaques and diffuse pleural thickening. This study was undertaken to determine the prevalence and causes of diffuse thickening in asbestos-exposed persons. Serial chest radiographs in 1373 exposed individuals and 717 controls were interpreted according to the ILO scheme by two B readers. Diffuse pleural thickening was defined as a smooth, noninterrupted pleural density extending over at least one-fourth of the chest wall, with or without costophrenic angle obliteration. Among the exposed group, plaques and diffuse thickening occurred with almost equal frequency, 16.5% and 13.5%, respectively. Of the 185 cases with diffuse thickening, the radiographic appearance was most often due to the residual of a benign asbestos effusion (31.3%) or confluent plaques (25.4%). The most commonly held explanation of diffuse thickening, an extension of pulmonary fibrosis to the visceral and parietal pleura, was actually infrequent (10.2%). Among the group with diffuse thickening without asbestosis, the forced vital capacity and single-breath diffusing capacity were significantly lower than those of comparable normal persons and those with confluent plaques.

Pulmonary veno-occlusive disease in the middle-aged.

Pulmonary veno-occlusive disease (PVO) is an uncommon cause of pulmonary hypertension which is difficult to diagnose without histology. We report 3 cases of histologically confirmed PVO. Our patients were all middle-aged or older, and 1 had spontaneous improvement in his symptoms suggesting that PVO may occur more commonly among older adults than previously believed and that indolent forms of the disease may exist. As new therapeutic approaches to the various entities causing pulmonary hypertension are developed, it is increasingly important to determine precisely which condition is present in a given patient.

Chronic diffuse infiltrative lung disease. Newer approaches.

A new scheme for description of diffuse infiltrative lung diseases using the graphic terminology of the International Labour Office Classification is described. Conventions for grading the type (rounded, or "pqr," and irregular, or "stu"), severity (profusion in 12 steps), localization of opacities, and pleural disease were retained. Modifications included (a) a third group of opacities, called "xyz," corresponding to reticulonodular patterns; and (b) "ground glass" (alveolar) patterns, subdivided into seven types by character and location. In a study of 365 cases proven by open biopsy, when this scheme was used without any knowledge of clinical data, the first two radiologic diagnostic choices corresponded with the principal histologic diagnosis in 50 per cent of cases. This classification provides an understandable and quantifiable system of communication and a tool for teaching, clinical research, and epidemiologic studies.

Crackles in the early detection of asbestosis.

We studied 386 workers exposed to asbestos to assess the value of chest auscultation by a trained technician in detecting asbestosis as defined by previously reported clinical, physiologic, and roentgenologic criteria. The presence and degree of crackles were assessed at preselected basilar lung sites by a technician whose performance was validated by comparison with computer-generated time-expanded waveforms of tape recordings of lung sounds. Asbestosis was present in only 2.8% of the total population, but it was present in 8.6% of those with over 25 yr or more of employment. The technician correctly identified all the workers in whom the diagnosis was most certain, that is, those with all criteria positive. The overall true positive rate was 55%. The majority (94.8%) of those with no abnormal criteria were correctly classified. Auscultation by an objectively validated technician can be a useful noninvasive method for screening industrial populations exposed to asbestos.

Exercise alveolar-arterial oxygen pressure difference in interstitial lung disease.

Abnormality of gas exchange is best evaluated by the exercise alveolar-arterial oxygen pressure difference, P(A-a)O2. We studied the P(A-a)O2 in 168 patients with sarcoidosis, desquamative interstitial pneumonia (DIP), usual interstitial pneumonia (UIP), berylliosis, and asbestosis who were seen for clinical and disability consultations. The increase of P(A-a)O2 with exercise was greatest in UIP (mean 16 mm Hg), least in sarcoidosis (mean 1 mm Hg), and intermediate in DIP, berylliosis, and asbestosis (means 9, 9, and 7 mm Hg, respectively). The increase was best predicted by the single breath diffusing capacity (Dsb), and it occurred in patients with sarcoidosis and DIP if the Dsb was less than 50 percent predicted and in patients with the other diseases if the Dsb was less than 70 percent predicted. However, the magnitude of the increase could not be predicted from resting tests, even when multilinear regression equations were used. We conclude that for clinical evaluation of patients with interstitial lung disease, the exercise test with arterial blood gas measurement adds important information if the Dsb is less than 70 percent predicted. For disability evaluation, the invasive exercise study may be helpful when there is a wide discrepancy between clinical findings and resting physiologic studies.

Diffuse infiltrative lung disease: a new scheme for description.

A scheme was devised for semiquantitative description of the diffuse infiltrative lung diseases using the graphic terminology of the International Labour Office and Union Internationale Contre le Cancer (ILO/UC) classification. Conventions for grading the type (rounded or "pqr" and irregular or "stu"), severity (profusion in 12 steps), localization of opacities, and pleural disease were retained. Modifications included: (a) a third group of opacities, called "xyz," corresponding to reticulonodular patterns; (b) "ground glass" (alveolar) patterns, subdivided into 7 types by character and location; (c) notations for severity of emphysema; and (d) hilar node enlargement. This initial study concerned diagnostic aspects and therefore was limited to 365 cases proved by open biopsy. When this scheme was used without any knowledge of clinical data, the first two radiologic diagnostic choices corresponded with the principal histologic diagnosis in 50% of cases. The biopsy diagnosis was mentioned among the first three choices in 78% of cases. It is concluded that this classification provides an understandable and quantifiable system of communication and a tool for teaching, clinical research, and epidemiologic studies.

Surgical management of emphysema.

The history of surgery for the treatment of emphysema and its complications is long and complex and, with improved understanding of the pathophysiology, most procedures have been discarded. Present clear indications for surgery are mainly large or increasing bullae that result in compression of apparently good lung tissue, and complications of bullous emphysema such as pneumothorax and infection. With localized giant bullae the results of local resection can be as dramatic as the effects of pleural drainage for tension pneumothorax. Lobectomy should not be undertaken until bullae have been removed locally and application of positive pressure has failed to reveal any expandable lung tissue--a rare situation. Resection of small bullae generally has no effect on lung function. The indications for resection of large bullae in the presence of diffuse emphysema require careful individual study. In such cases even a small increment of function may be of great clinical benefit, and there is evidence that longevity can be increased. Finally, two-stage local drainage of tension bullae may be indicated in those rare cases in which open thoracotomy cannot be considered for other reasons.

Intravascular bronchioloalveolar tumor (IV-BAT).

Intravascular bronchioloalveolar tumor (IV-BAT) is a recently described, histologically distinct, malignant, primary lung neoplasm. Originally it was believed to arise from type II alveolar cells which invade blood vessels within the lung, and hence its name. More recent ultrastructural studies suggest an origin from mesenchymal cells, and therefore the tumor may be more appropriately considered a sarcoma. The onset of the disease may be insidious, and its clinical course may vary from slow to rapid progression. A history is present of a young woman with slowly enlarging multiple ill defined pulmonary nodules. Open lung biopsy was diagnostic of IV-BAT. The clinical course, differential diagnosis and pathogenesis of this tumor are briefly discussed.