IUHS Student-2-Student USMLE Step 1 Recall

                                                    Respiratory

                                    Diffuse Interstitial Lung Disease

Goodpasture Syndrome

Goodpasture syndrome is an uncommon but intriguing condition characterized by the simultaneous appearance of proliferative, usually rapidly progressive glomerulonephritis and a necrotizing hemorrhagic interstitial pneumonitis...

most cases begin clinically with respiratory symptoms, principally hemoptysis, and radiographic evidence of focal pulmonary consolidations...

soon, manifestations of glomerulonephritis appear, leading to rapidly progressive renal failure...

the common death is uremia...most cases occur in the teens or twenties, and there is preponderance among men...

linear deposits of immunoglobulins and complement are also seen by immunofluorescence studies along the glomerular basement membranes, similar to those in the alveolar septa...

prognosis has improved over the years due to plasma exchange...

this procedure is thought to be beneficial by removing circulating anti-basement membrane antibodies as well as chemical mediators of immunologic injury...

simultaneous immunosuppressive therapy inhibits further antibody production...

both the lung hemorrhage and the glomerulonephritis improve with this form of therapy...

Anti-GBM are present serologically...

Bronchiolitis Obliterans Organizing Pneumonia (Boop)

refers to what is now recognized to be a common response to infectious or inflammatory injury of the lungs...

patients present with cough and dyspnea and often recall a recent respiratory tract infection...

patchy opacities or interstitial infiltrates are seen radiologically...

comprises of polypoid plugs of loose, fibrous tissue filling both bronchioles (bronchiolitis obliterans) and alveoli (organizing pneumonia)...

a variable chronic inflammatory cell infiltrate usually accompanies what appears to be a prolonged effort to resolve or organize the pulmonary injury...

causes associated with bronchiolitis obliterans organizing pneumonia include infections (viral, bacterial), inhaled toxins, drugs, collagen vascular disease, and graft-versus-host disease in bone marrow transplant recipients...

the bronchiolar injury and repair distinguish this process from routine pneumonias...

Bronchiolitis is a nonspecific finding with many lung diseases. Bronchiolitis obliterans (BO) develops to some degree in virtually every transplanted lung. BO is probably a form of chronic rejection and leads to fibrosis and obliteration of small peripheral airways.

Hypersensitivity Pneumonitis

describes a spectrum of immunolgically mediated, predominantly interstitial lung disorders caused by intense, often prolonged exposure to inhaled organic dusts and related occupational antigens....

most commonly hypersensitivity results from the inhalation of organic dust containing antigens made up of spores of thermophilic bacteria, true fungi, animal proteins, or bacterial products...

alterations in lung histology include, interstitial pneumonitis consisting primarily of lymphocytes, plasma cells, and macrophages, interstitial fibrosis, obliterative bronchiolitis, and outright granuloma formation...

recurring attacks of fever, dyspnea, cough, and leukocytosis...

diffuse and nodular infiltrates appear in the chest radiograph, and pulmonary function tests show an acute restrictive effect...

symptoms usually occur 4-6 hours after exposure...

progressive respiratory failure, dyspnea, and cyanosis and a decrease in total lung capacity and compliance...

Desquamative Interstitial Pneumonitis (or Interstitial Fibrosis)

prominent aggregation of mononuclear cells (macrophages) within the alveoli, originally thought to be desquamated epithelial cells from the alveolar walls...

these patients usually present with the slow development of cough and dyspnea, eventually leading to marked respiratory embarrassment, cyanosis, and clubbing of the fingers...

classicaly the radiologic picture is that of bilateral lower-lobe, ground glass infiltrates...

responds to administration of steroids in treatment...

Sarcoidosis

systemic disease of unknown cause characterized by noncaseating granulomas

in many tissues and organs...

bilateral hilar lymphadenopathy or lung involvement is visible on chest radiographs in 90% of cases...eye and skin lesions are next in frequency...

the prevelance of sarcoidosis is higher in women than in men but varies widely in different countries and populations...in the US, rates are highest in the southeast, and ten times higher in blacks...

the distinctive granulomatous tissue response seen in sarcoidosis suggests the presence of a persistent, poorly degradable antigen...numerous intriguing immunologic abnormalities are present, including increases in CD4+ lymphocytes within the lung and elevated levels of soluble IL-2 receptors in serum and lung lavage fluid...

epitheliod histiocyes must be present for the diagnosis of sarcoidosis...Asteroid Bodies...

alveolar macrophages also show an activated phenotype, with increased class II HLA expression and increased antigen presenting capacity...

the cytokines and factors secreted by these cells could well account for the influx of monocytes, alveolitis, and noncaseating granuloma formation in the lung and for the resulting progressive fibrosis, all characteristic features of pulmonary sarcoidosis...

blood levels of angiotensin-converting-enzyme (ACE) are increased and this may be used as a clinical test...

hypercalcemia due to hypervitamintosis D...

chest films may show bilateral hilar adenopathy or may have peripheral lymphadenopathy, cutaneous lesions, eye involvement, splenomegaly, or hepatomegaly as a presenting manifestation...

insidious onset of respiratory abnormalities (shortness of breath, cough, chest pain, hemoptysis) or of constitutional signs and symptoms (fever, fatigue, weight loss, anorexia, night sweats)...

65-70% of affected patients recover with minimal or no residual manifestations...20% have permanent loss of some lung function or some permanent visual impairment...remaining 10% die of cardiac or CNS damage, but most succumb to progressive pulmonary fibrosis and cor pulmonale...

noncaseating granulomas...schaumann bodies: laminated calcifications...asteroid bodies: stellate giant cell cytoplasmic inclusions...

Coal Workers Pneumoconiosis (Anthracosis)

spectrum of lung findings in coal workers is wide, varying from (1) asymptomatic anthracosis, in which pigment accumulates without a perceptible cellular reaction, (2) simple coal workers pneumoconiosis (CWP), in which accumulation of macrophages occur with little to no pulmonary dysfunction, to (3) complicated CWP, or progressive massive fibrosis (PMF), in which fibrosis is entensive and lung function is compromised...

it appears that fewer than 10% of cases of simple CWP progress to PMF...PMF is a generic term that applies to a confluent, fibrosing reaction in the lung that can be a complication of any pneumoconiosis, although it is most common in CWP and silicosis...

Caplan's Syndrome - association of rheumatoid arthritis and pulmonary nodules in patients with pneumoconiosis, particularly coal workers pneumoconiosis...

Simple CWP - coal macules are 1 to 2 mm in diameter...

Complicated CWP - intensely blackened scars greater than 2 cm, sometimes up to 10cm in greatest diameter...

usually benign disease that causes little decrement in lung function...

in a minority of cases PMF develops, leading to increasing pulmonary dysfunction, pulmonary hypertension, and cor pulmonale...

once PMF develops, it may become progressive even if further exposure to dust is prevented...

increased incidence of TB...

Silicosis

silicosis is a lung disease caused by inhalation of crystalline silicon dioxide (silica)...

currently the most prevalent chronic occupational disease in the world, silicosis usually presents, after decades of exposure, as a slowly progressing, nodular, fibrosing pneumoconiosis...

sandblasters and many mine workers are at risk...

heavy exposure over months to a few years can result in acute silicosis, a lesion characterized by the generalized accumulation of a lipoproteinaceous material within alveoli...

early in the disease there are multiple, very small nodules in the upper zone of the lungs, which produces a fine nodularity on x-ray...

these areas histologically show fibrosis and birefringment particles...the fibrotic lesions may also be found in the hilar lymph nodes, which can become calcified and have an "eggshell" pattern on x-ray examination...

eventually may lead to white out of lung in x-ray appearance...

quartz is most commonly implicated in silicosis...after inhalation, the particles interact with epithelial cells and macrophages to initiate injury and cause fibrosis...

the mechanisms of tissue and cell injury by crystalline silica are thought to be based on the chemical reactivity of the particle surface...

SiOH groups on the surface form bonds (hydrogen and electrostatic) with membrane proteins and phospholipids, which leads to denaturation of membrane proteins and damage to the lipid membranes...

in addition, surface free radicals are generated during the cleavage of silica...this initially high surface chemical reactivity makes freshly ground silica substantially more cytotoxic in vitro than its aged counterpart...

eventually may lead to white out of lung in x-ray appearance...

lung macrophages that ingest the silica particles may ultimately succumb to the toxic effects described earlier, silica caused activation and release of mediators by viable macrophages...

mediators identified include IL-1, TNF, fibronectin, lipid mediators, oxygen derived free radicals, and fibrogenic cytokines...

anti-TNF monoclonal antibodies can block lung collagen accumulation in mice given silica intratracheally...

individuals with silicosis are at an increased risk for TB...

Growth factors are released from macrophages that have ingested silica crystals and these factors stimulate collagen production by fibroblasts

disease is usually detected when routine chest radiography is performed on an asymptomatic worker...

the radiographs typically show a fine nodularity in the upper zones of the lung, but pulmonary functions are either normal or only moderately affected...

most patients do not develop shortness of breath until late in the course, after PMF is present...

disease is slow to kill, but impaired pulmonary function may severely limit activity...

Asbestos-Related Diseases

localized fibrous plaques or, rarely diffuse pleural fibrosis...pleural effusions...parenchymal interstitial fibrosis (asbestosis)...bronchogenic carcinoma...mesotheliomas....larngeal and perhaps other extrapulmonary neoplasms, including colon carcinomas...

the term ferruginous body is applied to other inhaled fibers that become iron coated; however, in a patient with interstitial lung fibrosis or pleural plaques, ferruginous bodies are probably asbestos bodies...

pleural plaques are detected on radiographs as circumscribed densities...

primary lung cancer (bronhogenic carcinoma) is more apt to appear than mesotheliomas in a 25 year old...mesotheliomas take over 25 years to evolve where primary lung cancer takes about 5-10 years to evolve...

2 Professions most likely to get:

roofers and workers in a naval ship yard...

amphibole (straight-stiff, and brittle fibers)...

some studies of mesotheliomas have shown the link is almost always to amphibole exposure...

amphibole exposure correlates with mesothelioma...

the term ferruginous body is applied to other inhaled fibers that become iron coated; however, in a patient with interstitial lung fibrosis or pleural plaques, ferruginous bodies are probably asbestos bodies...

pleural plaques are detected on radiographs as circumscribed densities...

dyspnea is usually the first mainifestation, at first, it is provoked by exertion, but later it is present even at rest...

cough associated with production of sputum...

the disease may remain static or progress to congestive heart failure, cor pulmonale, and death...

chest films reveal irregular linear densities, particularly in both lower lobes...

honeycomb pattern develops...

pleural plaques are detected on radiographs as circumscribed densities...

the segmented or beaded, often dumbbell shapaed bodies are ferruginous bodies that are probably asbestos fibers coated with iron and protein...

the term ferruginous body is applied to other inhaled fibers that become iron coated; however, in a patient with interstitial lung fibrosis or pleural plaques, ferruginous bodies are probably asbestos bodies...

Berylliosis

heavy exposure to airborn dusts or to fumes of metallic beryllium or its oxides, alloys, or salts may induce acute pneumonitis, more protracted low dose exposure may cause pulmonary and systemic granulomatous lesions that closely mimic sarcoidosis....

chronic berylliosis is caused by induction of cell-mediated immunity...it appears that genetic susceptibility is necessary for the initiation of an immune response...

the development of delayed hypersensitivity leads to the formation of noncaseating granulomas in the lungs and hilar nodes or, less commonly, in the spleen, liver, kidney, adrenals, and distant lymph nodes...

the pulmonary granulomas become progressively fibrotic, giving rise to irregular, fine nodular densities detected on chest radiographs...hilar adenopathy is present in about half the cases...

dyspnea, cough, weight loss, and arthralgias are common clinical signs...