Bronchiolitis obliterans organizing pneumonia.

Bronchiolar disorders can be divided into 2 general categories: (1) airway disorders (cellular bronchiolitis and obliterative bronchiolitis) and (2) parenchymal disorders (respiratory bronchiolitis-interstitial lung disease, which occurs in smokers and is treatable with smoking cessation or corticosteroid therapy, and bronchiolitis obliterans organizing pneumonia, an inflammatory lung disease simultaneously involving the terminal bronchioles and alveoli). This article reviews the clinical findings and therapeutic management of bronchiolitis obliterans organizing pneumonia.

Heterogeneity of bronchiolitis obliterans organizing pneumonia.

Reports of the characterization and understanding of bronchiolitis obliterans organizing pneumonia (BOOP) have continued at an accelerated rate for several years. The radiographic and high-resolution CT features of BOOP continue to be documented. There have been new insights into the pathogenesis of BOOP. An animal model has been developed. Video-assisted thoracoscopic biopsy has become a standard for confirming the diagnosis. Childhood BOOP has been described in several reports. Idiopathic BOOP continues to be the most common type; however, a variety of clinical settings such as inhalation of mold spores and associated disorders such as renal transplantation continue to be described. This paper provides an update of advances in the pathogenesis, radiographic features, clinical course, and categorization of the heterogeneity of BOOP.

Bronchiolar disorders with airflow obstruction.

Bronchiolar lesions continue to be increasingly recognized as a cause of airflow obstruction. Thus, it is important to have a current update of the current clinical, radiographic, and immunologic perspective of these disorders. Diffuse panbronchiolitis has been reported to occur in the United States and Europe, and the anti-inflammatory action of erythromycin appears to be effective in management. Idiopathic bronchiolitis obliterans, post-fume or post-infectious, or connective tissue disorder bronchiolitis obliterans continues to be rare and often has a poor prognosis. Lung transplantation bronchiolitis obliterans continues to be the major complication and cause of mortality in transplant recipients. Risk factors of this form of chronic rejection include more frequent and more severe acute rejection and the coexistence of organizing pneumonia. The recognition of the distinctive differences among the bronchiolar airflow disorders continues to be essential for improved patient care, greater understanding of the pathogenesis, and development of therapeutic advances.

Bronchiolitis obliterans organizing pneumonia.

Bronchiolitis obliterans organizing pneumonia (BOOP) is increasingly recognized as an important cause of diffuse infiltrative lung disease. It is a diagnostic consideration in patients with a febrile flu-like illness of a few weeks' duration and a roentgenogram showing bilateral patchy infiltrates that are not responsive to a typical course of antibiotics. It is defined as granulated tissue plugs within lumens of small airways that extend into alveolar ducts and alveoli. Clinically, a flu-like illness, cough, and crackles are common. Pulmonary function studies of patients show a decreased vital capacity, normal flow rates (except in smokers), and a decreased diffusing capacity. It is generally idiopathic, but it may occur during the resolution of a viral or mycoplasma pneumonia. It is also associated with a variety of systemic illnesses and clinical settings. These include the connective tissue disorders, antineoplastic and other drugs, and immunological disorders, as well as bone marrow and lung transplantation. There are numerous related disorders, including human immunodeficiency virus infection, radiation therapy, thyroiditis, and alcoholic cirrhosis. In idiopathic BOOP, complete resolution occurs in 65% to 85% of patients treated with corticosteroid therapy. This type of therapy is often effective in patients with associated systemic disorders or in other clinical settings, but there may be limited or no response in patients with dermatomyositis, immunosuppression, or interstitial opacities at the lung bases. Respiratory failure leading to death may occur in 5% of patients. It is important to add BOOP to the differential diagnosis of febrile, noninfectious illnesses that are mimics of pneumonia.

Bronchiolitis with airflow obstruction.

Bronchiolar lesions are becoming increasingly recognized as an important cause of airflow obstruction. For this reason, it is helpful to have an update of the current clinical, radiographic, and immunologic perspective. Among the bronchiolar airflow disorders, diffuse panbronchiolitis is related to HLA antigen Bw54, and low-dose, long-term erythromycin appears to be effective therapy. Bronchiolitis obliterans can be classified histologically as constrictive bronchiolitis and as proliferative bronchiolitis obliterans. Idiopathic, postfume, postinfectious, and connective tissue disease bronchiolitis obliterans continue to be rare and often have a poor prognosis. Bronchiolitis obliterans associated with lung transplantation is undergoing intensive investigation with regard to pathogenesis, immunologic study, early detection, and treatment. The lesion appears to be a form of chronic organ rejection. The recognition of the distinctive differences among the bronchiolar airflow disorders by clinicians and clinical investigators is essential for improved patient care, for a greater understanding of the pathogenesis of the disorder, and for development of new therapeutic advances.

Clinical overview of occupational lung disease.

The workplace has been a source of lung injury for centuries, yet awareness of the types of injuries has varied over time. Because of distinctive differences among the occupational lung disorders, a continual update of the clinical findings, dose response data, physiologic characteristics, and radiographic findings is needed. The radiologist plays a key role for the evaluation of miners, foundry or factory workers exposed to mineral dusts, and of workers exposed to the "biologic" dusts, infectious agents, cancer causing agents, and chemicals causing interstitial lung diseases. This overview includes a discussion of classification systems, criteria for diagnosis of occupational lung diseases, the pulmonary clinician's evaluation, and important aspects of specific disorders and concludes with a discussion of pulmonary disability determination.

Bronchiolitis obliterans organizing pneumonia: definition and clinical features.

There are several bronchiolar diseases with different pathologic and clinical findings. Idiopathic BOOP is a distinct entity consisting of a flu-like illness, late inspiratory crackles, patchy infiltrates roentgenographically, and physiologically decreased vital capacity and diffusing capacity. Response to corticosteroid therapy is good and relapse does not occur if sufficient therapy is given. Bronchiolitis obliterans organizing pneumonia is an appropriate description of this entity. The term is specific because it includes bronchioles and alveoli and excludes disorders involving only alveoli such as organizing pneumonitis or organizing diffuse alveolar damage. The term is general enough to include a sufficient number of patients with a homogenous disorder. Furthermore, the entity can be described to clinicians and pathologists throughout the world in such a fashion that patient care and research can be standardized. Researchers from different centers studying the cause or utilizing treatment protocols are able to discuss a single BOOP entity rather than comparing results of a heterogeneous group of many different types of interstitial lung disorders. This will lead to breakthroughs in discovery of etiologic causes and new effective therapeutic regimens.

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.

Screening for lung cancer. Is it worthwhile?

Prevention of lung cancer remains the best method of decreasing lung cancer mortality. Patients who smoke should be urged to quit, and children, teenagers, and young adults must not begin smoking. At high risk are smokers, especially those under 40 years of age who may have smoked two to four packs of cigarettes per day for 20 years; persons who have had a previous lung cancer; patients with bullous emphysema; patients with asbestosis; and patients with evidence of chronic airflow obstruction. Although radiographic screening may detect lung cancer earlier and lead to increased 5-year survival rates, it does not reduce lung cancer mortality rates.

Bronchiolitis obliterans and airways obstruction associated with graft-versus-host disease.

Bronchiolitis obliterans is a nonspecific pathologic lesion seen after fume inhalation and infections, which is associated with connective tissue disorders and is a complication of organ transplantation. Bronchiolitis obliterans with organizing pneumonia is also associated with the connective tissue disorders but is usually idiopathic and has better prognosis with corticosteroid therapy. Bone marrow-related obliterative bronchiolitis is limited to patients who develop chronic graft-versus-host disease. Symptoms begin with cough in 3 to 6 months and progress to dyspnea and severe airflow obstruction. The roentgenogram is normal or shows hyperinflation. Prognosis is poor and most patients develop disabling irreversible airflow obstruction. Bronchiolitis obliterans is the most important clinical complication in heart-lung transplant recipients. It is not preceded by typical features of chronic graft-versus-host disease, but has the same clinical course of dyspnea, airflow obstruction, and poor response to therapy. Bronchiolitis obliterans in transplant recipients may represent a form of allograft rejection.

Pleural lipoma. Diagnosis by computed tomography.

Until recently, a definitive diagnosis of lipoma in the thorax could only be established by thoracotomy. We undertook this study to determine if chest CT could provide such an answer. Among 4,000 chest CT scans, six patients were found to have lipoma according to the following selected criteria: CT features of a pleural mass; a lesion showing completely homogeneous density with CT numbers indicating fat, and exclusion of other fatty lesions. In these six patients, the lipoma was an incidental finding, four were men, the mean age was 64.3 years, one-half were obese, and none had chest pains or dyspnea. Lesions varied in size from 2 to 4 cm and occurred along the chest wall. The CT numbers of the masses ranged from -54 to -129. None developed malignancy. In conclusion, we recommend clinical and chest CT follow-up for the asymptomatic patient who fulfills our CT criteria for lipoma. Biopsy or resection is recommended for lesions that are inhomogeneous.

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.