Tuesday, April 2, 2013

Idiopathic Fibrosing Alveolitis (Hamman-Rich Syndrome)

LV Hamman, Amer. Physician, 1877-1946; AR Rich, Amer. Physician, was born in 1893; synonyms: idiopathic pulmonary fibrosis) - a progressive inflammatory lung lesion of unknown nature, which leads to the development of diffuse fibrosis, chronic respiratory and cardiopulmonary failure.
Hamman-Rich syndrome is a rare disease characterized by rapidly progressive diffuse pulmonary fibrosis with the development of respiratory failure, pulmonary hypertension and cor pulmonale.

 Etiology. Hereditary disease with autosomal dominant type of inheritance.
Pathogenesis. Previously in the development of syndrome there was attached importance of auto-sensitization in connection with which diseases was entered to a group of connective tissue disease. Now there is considered that the syndrome occurs as the result of repeated inflammatory bronchopulmonary diseases. Morphological substrate is perialveolar fibrosis, which reduces the elasticity and pliability of lung tissue and thus worsens the excursion of the lungs. Due to the thickening of the interalveolar septa diffusion of gases in the blood is damaged, which leads to hypoxemia and hypoxia, hypercapnia.

                    The disease manifests itself mainly in school age children and adolescents, but the first signs of it (on history) almost half of the patients are detected in pre-school age. The disease begins gradually after an attack of influenza, repeated pneumonia, bronchitis and often measles. There are a spastic, dry cough, shortness of breath and cyanosis during physical exertion, sometimes chest pain, feeling of tightness in the chest.
                    Percussion defines an insignificant shortening of sound in the basal zones or no change, decrease of excursion of lungs, reducing difference of lung volume during inspiration and expiration. Auscultation reveals inconstant fine bubbling or crepitation moist rales, sometimes may be weakening of breathing in the lower areas.
                   Further there are increasing of cyanosis around the mouth, acrocyanosis, fingers take the form "drumsticks". The child retards in weight and growth. Thorax is flattened, circumference of the neck disproportionately increases (due to increased contractility of the neck muscles that perform the role of auxiliary respiratory muscles during difficult breathing). Pulmonary heart syndrome is developing with the expansion of the cardiac dullness, signs of cardiovascular failure.

              In the blood – polycythemia, may be polyglobulinemia, ESR is increased, especially in acute periods, concentrations of gamma-globulin is elevated.
             The study of respiratory function reveal the decline of lung volumes, reduced lung compliance and difficulty in passing the oxygen through the alveolar-capillary membrane, and therefore change in the gas composition of the blood (hypoxemia, then hypercapnia) and indicators of acid-base status.

                    After treatment with corticosteroids LVC, total lung capacity, the inspiratory volume is practically unchanged. Radiological investigation in the initial period reveals that the interstitial pattern is enhanced, later nodular formation appear on its background. In periods of exacerbations there is determined multiple shadowing, alternating with areas of particularly clear lung fields. Shadowing is usually localized in the roots and lower parts. Pneumothorax may be possible complication.


                                                   Representative CT scan image from a person with
                                                        idiopathic pulmonary fibrosis.
                                                                    Idiopathic fibrosing alveolitis.
Detail of chest radiograph with                                                                          interstitial pneumosclerosis with a primary lesion of the alveolar connective tissue (fibrosing alveolitis):  small meshy pattern of lung.

Micropreparations of lung at diffuse interstitial pneumosclerosis: interseptums are extremely thickened and sclerotic; coloured by Van Gieson; × 24.

A. Lung showing extensive interstitial and alveolar fibrosis.
    Note the increased interstitial cellularity with numerous fibroblasts.
B. Patchy areas of alveolar septal thickening and prominent hyaline membranes.
C. Higher magnification showing typical dense laminated hyaline membranes.
D. Alveolar septum showing prominent type II pneumocyte proliferation.
E. Abundant polymorphonuclear leukocytes fill alveolar spaces with focal destruction of alveolar septa.
F. Higher power magnification showing the antraalveolar exudate
composed mainly of polymorphonuclear leukocytes, red blood cells, and fibrin.

Original magnifications: A & B, x 50; C, x 100; D, x 158; E, x 50; F, x 158.

Electron-microscopic picture of fibrosed alveoli.

                    CT-image of meshy lung

Vacuolization of macrophages in amiodarone alveolitis. Materials obtained through bronchoalveolar lavage.

            The disease is undulating with periods of exacerbation and remission. However, remission time zone fibrotic changes do not disappear, and rates of respiratory still significantly reduced. Depending on the frequency and duration of periods of exacerbation, some authors distinguish subacute and chronic forms of course. In subacute form periods of exacerbation are more frequent, accompanied by fever reaction, while at chronic progression of pulmonary fibrosis occurs gradually and manifests the growth of respiratory failure. At present, long-term treatment of patients with corticosteroid differences within these two forms have become less pronounced. There are two clinical forms of idiopathic diffuse pulmonary fibrosis depending on diffusion of gases in the lungs. In most cases diffusion capacity is decreased, but in 10-15% of patients it is within normal limits. In such patients the process is easier, retarded growth and weight are insignificant or absent.
               Diagnosis is mainly based on typical clinical signs of disease.
                  Diagnostic criteria of IFA
·                               progressive dyspnea
·                               cyanosis
·                               dry cough
·                               progressive loss of weight
·                               tender crepitation wheezing
·                               thickening of hand phalanges nails
·                               diffuse fibrosis
·                               deformation of the pulmonary pattern
·                               presence of focal shadows
Indicators of external respiration
·                               decrease of lung volumes
·                               hypoxemia
Indicators of regional lung function
·                               diffuse irregular distribution of radionucleids
·                               regional lung volume reduction
·                               smoothing apex-basal ingredients
                       Differential diagnose.
                 Differential diagnosis should be carried out with exogenous allergic alveolitis caused by the inhalation of various organic antigens. Such condition is observed in children with close and prolonged contact with animals and birds. Clinically, the disease is very similar to idiopathic diffuse pulmonary fibrosis. Exogenous allergic alveolitis is diagnosed based on the detection of precipital antibodies against animal serum and excrements. Excluding the effects of antigen in combination with corticosteroid therapy in such patients may lead to recovery. In idiopathic pulmonary fibrosis diffused all lung volumes, lung elasticity during therapy with corticosteroids did not decreased even at satisfactory state of health of patients and the absence of exacerbations process.
             Corticosteroid therapy is used. Originally prednisolone is prescribed at a dose of 1 mg / kg per day. The dose is gradually reducing, but maintenance therapy (5-10 mg prednisolone per day), continue for many months. In severe progressive course corticosteroids are combined with cytostatic drugs (azathioprine, etc.). During exacerbations, the accession of pneumonia, bronchitis, corticosteroids are combined with antibiotics. In addition, antihistamines, vitamins, symptomatic treatment is used.
                             Prognosis is unfavorable.

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