Constructive bronchiolitis obliterans, is a form of respiratory illness involving a person's small airways that is important due to its fibrotic and irreversible nature.
The terminology used to describe the bronchiolar diseases vary throughout nations around the world. A pathologist uses the term, constrictive bronchiolitis,' and reports the lesion whether there is an airway obliteration or not. The clinical significance of the disease is usually associated with obliteration of the person's bronchiolar airways.
Differentiating between forms of lesions is important because the treatment and outcomes of them is notably different. A fibrotic constrictive lesion usually develops externally in a person's airway lumen, constricting their airway in a concentric way that eventually obliterates their lumen. Inflammatory proliferative lesion, on the other hand, develops internally from a person's airway wall, filling their lumen with an inflammatory proliferative lesion of loose connective tissue or, 'buds,' of granulation. Concentric bronchiolitis obliterans commonly involves a person's mid-bronchiolar region, with proliferative lesion often involving the person's distal bronchioles, many times extending into their alveolar spaces. Such a lesion is called, 'bronchiolar obliterans organizing pneumonia,' or, 'BOOP.'
Should the proliferative lesion a person experiences involve their mid-bronchiolar airways without alveolar involvement, their physiologic and radiographic results might be indistinguishable from a constrictive lesion. The person's response to treatment; however, is very different. A fibrotic concentric lesion does not respond to corticosteroid therapy; an intraluminal inflammatory lesion does, commonly resulting in a cure.
If the person experiences a proliferative lesion involving both of their distal bronchiole airways and their alveoli it is considered to be BOOP. There are many clinical and treatment differences between this form of lesion and constrictive bronchiolitis obliterans. Constrictive bronchiolitis obliterans is a form of irreversible airflow obstruction disease involving early symptoms such as, 'squeaks,' or, 'crackles,' when a person breathes in. The person presents with normal findings on their chest x-ray, and has air-trapping on their expiratory high-resolution chest CT.
BOOP is a form of interstitial disease. People who experience it have symptoms such as crackles at the end of their inhalation, a chest x-ray revealing bilateral patchy infiltrates, an abnormal diffusing capacity, as well as high-resolution CT results showing ground-glass opacities and air bronchiograms. Constrictive bronchiolitis obliterans does no respond to corticosteroid therapy and people with it have a poor prognosis. People who experience BOOP do respond well to steroid therapy and have a good prognosis. It is highly important for a pathologist and a clinician to distinguish between these two lesions in a person who is affected.
There are a number of causes of constrictive bronchiolitis obliterans, as well as the various related conditions. Among the related conditions are:
The idiopathic form is very rare, while post-bone marrow transplant constrictive bronchiolitis occurs in approximately ten-percent of people who have had such a transplant. Post-lung transplant lesions might occur in nearly sixty-percent of people. Drug-related and post-respiratory infection related constrictive bronchiolitis obliterans are rare. Bronchiolitis obliterans causes by the inhalation of fumes and oral toxins continue to be reported.
Soldiers are coming home from the war in Afghanistan with constrictive bronchiolitis. The disease can only be diagnosed through a biopsy. Soldiers have been exposed to, 'burn pits,' in not only Afghanistan, but during the war in Iraq as well. Some of these burn pits are as large as football fields, and contain things such as sulfur in them.
Toxic Fume Inhalation and Oral Toxin Exposure Constrictive Bronchiolitis
Specific toxic fumes can cause the concentric bronchiolitis obliterans lesion, or the proliferative intraluminal bronchiolitis obliterans lesion. The traditional concentric bronchiolitis obliterans lesion from toxic fumes happen as in three-phases. In the first phase, the person does not experience any symptoms for a few hours. In the second phase, the person experiences Acute Respiratory Distress Syndrome or ARDS. During phase three, the person experiences another period without apparent symptoms for a number of days, then experiences constrictive bronchiolitis obliterans with irreversible airflow obstruction. The disorder has happened in people after exposure to acid-based toxic fumes, such as sulfur dioxide.
The prognosis for people who experience constrictive bronchiolitis obliterans is often times poor. The person's outcome is dependent upon the severity of the process, as well as whether or not there is a progressive nature to their lesion. Therapy with corticosteroids does not have an effect on end-stage fibrotic process. Acute exacerbations associated with an inflammatory response; however, might be responsive to a course of corticosteroid therapy. The major complication of this disease is chronic respiratory failure.