Flock worker's lung

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief:

Synonyms and keywords: Synonym 1; Synonym 2; Synonym 3

Overview

Flock Worker's Lung.

Historical Perspective

• Since 1975, published case reports have raised suspicion of a respiratory hazard associated with various synthetic fibers, including polyester, nylon, and acrylic dust.
• Early reports in 1974 and 1981 of workplace evaluations by National Institute of Occupational Safety and Health (NIOSH) investigators attributed respiratory symptoms among workers to irritant properties of nonrespirable flock fibers on the upper airways but did not pursue the possibility of lung disease associated with flock work
• During 1990 and 1991, five workers from a nylon flock processing plant in Ontario presented with cough and dyspnea.
• In 1995 and 1996, two workers from a similar nylon flock processing plant in Rhode Island presented separately to the same physician with cough and dyspnea
• The initial working diagnosis for the lung disease in these two workers was work-related hypersensitivity pneumonitis. With additional case finding investigation at the Rhode Island location, a total of eight cases among the approximately 150 workers at the plant were identified by January 1998 based upon a screening questionnaire (symptoms of cough and dyspnea), pulmonary function abnormalities (restrictive pattern with reduced diffusing capacity), radiographic findings and/or histological findings on tissue obtained by open lung or transbronchial lung biopsy .Based upon the aggregate histopathological results from biopsied cases, the disease process was not thought to be hypersensitivity pneumonitis.
• "flock worker's lung" formally came to known in 1998, when researchers from NIOSH published the results of an epidemiological investigation of outbreaks in Ontario and Rhode Island.
• Previously, interstitial lung disease in flock workers was incorrectly attributed to mycotoxins present in contaminated adhesive.

Classification

The disease currently still has not been stratified.

Pathophysiology

• Flock consists of short fibers that are cut from long filaments and glued to backing material such as cloth to provide a fuzzy, carpet-like surface texture. They are usually prepared from synthetic materials such as nylon, rayon, or polypropylene. The cutting process results in formation of airborne particles or fibers in the respirable range. Inhalation of flock dust causes an interstitial lung disease.
• Preliminary toxicologic studies suggest that ultrafine respirable fragments of nylon cause an acute inflammatory lung injury in rats after a single intratracheal instillation. However, flock finishing agents or other components of the particulate matter present in the air of flock processing plants cannot yet be ruled out.
• The interstitial pneumonitis we have studied among nylon flock processing workers has a histopathological pattern— bronchiolar and peribronchiolar lymphocytic inflammation and lymphoid hyperplasia—which suggests an inflammatory and possibly immunologic response to a respirable toxic agent
• In one study microscopic examination of polypropylene fibre-exposed lungs revealed a dose-dependent increase in cellularity (especially macrophage infiltration), but no fibrosis. In another study , the researchers found high serum IL-8 and TNF-α levels in the polypropylene flocking workers. Furthermore, these levels showed a negative correlation with DL,CO. These results suggest that IL-8 and TNF-α may act as key mediators for inflammatory lung injury in the pathogenesis of polypropylene flocking worker's lung.

Causes

• FWL results from the inhalation of airborne nylon fibers at work. Nylon fibers are used in making products for upholstery, automobiles, carpet, and apparel.

Differentiating [disease name] from other Diseases

• [Disease name] must be differentiated from other diseases that cause [clinical feature 1], [clinical feature 2], and [clinical feature 3], such as:

• [Differential dx1]
• [Differential dx2]
• [Differential dx3]

Epidemiology and Demographics

Age

• Patients of all age groups may develop [disease name].

• [Disease name] is more commonly observed among patients aged [age range] years old.
• [Disease name] is more commonly observed among [elderly patients/young patients/children].

Gender

• [Disease name] affects men and women equally.

• [Gender 1] are more commonly affected with [disease name] than [gender 2].
• The [gender 1] to [Gender 2] ratio is approximately [number > 1] to 1.

Race

• There is no racial predilection for [disease name].

• [Disease name] usually affects individuals of the [race 1] race.
• [Race 2] individuals are less likely to develop [disease name].

Risk Factors

• Flock worker’s lung is seen in textile workers chronically exposed to short nylon fibers typically flocked onto textile products.Flock is produced by guillotine cutting or rotary cutting. Rotary cutting has been claimed to be more hazardous than guillotine cutting .

• Multivariate analyses showed that being a polypropylene flocking worker was a predictive factor for impairment of pulmonary function.
• A study showed that the risk of respiratory symptoms increased 3.6 fold in polypropylene flocking workers when compared to controls.

Natural History, Complications and Prognosis

The natural history of FWL includes the following patterns

• complete resolution of symptoms;
• radiographic and pulmonary function abnormalities;
• permanent, but stable symptoms and restrictive pulmonary function deficits;
• and progressive decline in pulmonary function, causing death from respiratory failure and secondary pulmonary hypertension. A low baseline diffusing capacity of the lung for carbon monoxide is associated with the persistence and progression of FWL

• In general, recovery occurred over a period of months or years after steroid treatment and leaving the place of work, with some having persistent dyspnoea, exercise limitation, or requirements for chronic supplemental oxygen.
• There was also threefold increase in lung cancer incidence.

Diagnosis

Diagnostic Criteria

A case of flock-worker's lung is defined as

1. a histologic diagnosis of nonspecific interstitial pneumonia characterized by bronchiolocentric nodular and diffuse interstitial lymphoid infiltrates and nonuniform alveolar filling by macrophages, with or without interstitial fibrosis;
2. Other histologic manifestations of Interstitial Lung Disease (ILD) not attributable to another disease; or
3. In the absence of a tissue specimen, a grossly abnormal distribution of cell types on bronchoalveolar lavage (BAL) with restrictive lung function and HRCT findings of either diffuse ground glass opacity or micronodularity.

• The diagnosis of [disease name] is made when at least [number] of the following [number] diagnostic criteria are met:

• [criterion 1]
• [criterion 2]
• [criterion 3]
• [criterion 4]

Symptom

A study showed 20 individual from different geographic locations having FWL shared symptoms of

• dyspnea and cough, with and without sputum production.
• These symptoms were present for months to years before clinical presentation, which, for some cases, seemed precipitated by an acute exacerbation in the preceding few days. Symptom onsets for the patients occurred over a 15-yr period, with no apparent concentration of onsets for any plant location.
• Few nonrespiratory symptoms were noted. Weight loss was noted in two patients and two workers had arthralgias or myalgias. Eight of the 20 patients were noted to have asthma, increased bronchial responsiveness to methacholine, or increased bronchodilator responsiveness.

• [symptom 1]
• [symptom 2]
• [symptom 3]
• [symptom 4]
• [symptom 5]
• [symptom 6]

Physical Examination

• Patients with [disease name] usually appear [general appearance].
• Physical examination may be remarkable for:

• [finding 1]
• [finding 2]
• [finding 3]
• [finding 4]
• [finding 5]
• [finding 6]

Laboratory Findings

• There are no specific laboratory findings associated with [disease name].

• A [positive/negative] [test name] is diagnostic of [disease name].
• An [elevated/reduced] concentration of [serum/blood/urinary/CSF/other] [lab test] is diagnostic of [disease name].
• Other laboratory findings consistent with the diagnosis of [disease name] include [abnormal test 1], [abnormal test 2], and [abnormal test 3].

Imaging Findings

• High-resolution CT scan remained a highly sensitive diagnostic test. Pulmonary function tests and plain chest radiograph were less sensitive.
• The most common findings in FWL on CT scan were ground-glass opacities and micronodules.

• There are no [imaging study] findings associated with [disease name].

• [Imaging study 1] is the imaging modality of choice for [disease name].
• On [imaging study 1], [disease name] is characterized by [finding 1], [finding 2], and [finding 3].
• [Imaging study 2] may demonstrate [finding 1], [finding 2], and [finding 3].

Other Diagnostic Studies

• [Disease name] may also be diagnosed using [diagnostic study name].
• Findings on [diagnostic study name] include [finding 1], [finding 2], and [finding 3].

Treatment

Medical Therapy

• There is no treatment for [disease name]; the mainstay of therapy is supportive care.

• The mainstay of therapy for [disease name] is [medical therapy 1] and [medical therapy 2].
• [Medical therapy 1] acts by [mechanism of action 1].
• Response to [medical therapy 1] can be monitored with [test/physical finding/imaging] every [frequency/duration].

Surgery

• Surgery is the mainstay of therapy for [disease name].
• [Surgical procedure] in conjunction with [chemotherapy/radiation] is the most common approach to the treatment of [disease name].
• [Surgical procedure] can only be performed for patients with [disease stage] [disease name].

Prevention

• There are no primary preventive measures available for [disease name].

• Effective measures for the primary prevention of [disease name] include [measure1], [measure2], and [measure3].

• Once diagnosed and successfully treated, patients with [disease name] are followed-up every [duration]. Follow-up testing includes [test 1], [test 2], and [test 3].