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What is a pneumoconiosis?

It is a disease of fibrosis of the lungs caused by inhalation of particulate matter, chemical fumes or vapors. Four factors influence the formation of penumoconiosis: 1) the amount of dust that stays in the lungs & airways 2) the size and shape of the particulates 3) the solubility and reactivity of the particulates and 4) the additional effects of other irritants such as tobacco smoke.

What size particles are the WORST, and why?
Worst are between 1 and 5 mm diameter because they are small enough to float deep into the lungs, and large enough that a macrophage can't eat them. Bigger particles usually get stuck in the mucus of the bronchi and bronchioles and are transported out by ciliary actions. Smaller particles get engulfed and removed via the lymphatic system.

What are some common inorganic dusts that tend to cause chronic pneumoconioses?
silicon, asbestos, beryllium (berylliosis), coal dust (anthracosis), iron oxide (siderosis)

Which one causes the prevalent chronic occupational disease worldwide?
silicon dioxide, a tetrahedral crystal-->silicosis

What are common sources of inhaled silicon dioxide?
ceramics, sand blasters, foundries, stone cutter, metal grinders

What are the effects of silicosis?
--the crystals are chemically reactive, causing lipid oxidation, free radical generation and protein denaturation
--silica kills macrophages when they try to engulf it
--before the macrophages commit apoptosis they release IL-1 and other mediators that increase fibrosis
--localized fibrosis becomes nodules
--nodules coalesce into collagenous scars
--lymph nodes calcify in hilar area-->eggshell calcifications that show up on x-ray or CT
--takes years to decades to develop
--first symptom is usually a cough, SOB only late in the dz course

Name the syndrome in which pneumoconiosis coexists with the development of rhematoid arthritis.
Caplan's Syndrome (commonly w/ asbestosis or silicosis)

Where does asbestos exposure happen?
mining industry, brake lining fabrications, insulation fabrication and installation, ship yard workers before 1970, old home refurbisher's as asbestos was used as fire retardant and insulator

What two forms do asbestos crystals take?
spiral or needle (.5 mm wide, up to 8mm long!)

Which form is more dangerous?
needle, because they pierce through tissue and impale in the pleura

What are some of the findings with asbestosis?
--pleural and sub-pleural fibrosis precedes signs of pulmonary fibrosis
--large, dense plaques form on both sides of pleural surface
--diffuse parenchymal dz that restricts lung movt: restrictive lung dz

What do you call asbestos needles that have been coated with proteins in the lung?
Asbestos bodies or ferruginous bodies (ferruginous according to some pathologists limited to meaning other protein-covered crystal with no evidence of asbestos core). Asbestos forms dumb-bell look or beaded look on needle.

How much does asbestos exposure increase your risk of bronchogenic cancer?
5x

If you are exposed to asbestos and smoke too, how much is your bronchogenic cancer risk?
55x

What tumor of the pleura is almost always associated with asbestos exposure?
mesothelioma

Does smoking increase the risk for developing mesothelioma?
the notes say that it does not (skeptical)

Workers in aerospace, nuclear and defense industries might be exposed to what dangerous alloy?
beryllium

When did the defense industry begin to monitor beryllium exposure in workers?
1940's

What is chronic berylliosis?
a cell mediated immune response to beryllium exposure

What is the characteristic lesion of berylliosis?
non-caseating granuloma surrounded by fibrotic lung tissue

What is CWP?
coal worker's pneumoconiosis, aka black lung disease

CWP rarely causes serious resp probs alone, but contributes to Caplan's syndrome when the pt develops what?
rheumatoid arthritis

Who gets iron oxide pneumoconiosis, aka siderosis?
welders

Organic pneumoconioses include type I (IgE), II (IgG/complex formation) and IV (cell mediated) allergic responses to what?
--spores, fungi, animal proteins, bacterial products, hay (actinomycetes), sugar cane mold (bagassosis), cotton/linen/flax/hemp (byssinosis)
--"farmer's lung", "pigeon keeper's lung", "mushroom picker's lung", "malt worker's lung", etc.

Why is it valuable to recognize these conditions early?
you can prevent serious fibrotic lung disease by removing the irritating agent

What's IPF?
--Idiopathic pulmonary fibrosis = same thing but with no obvious cause
--progressive: 4-6 years median survival time from dx
--alveolar glutathione levels are reduced
--alveolar macrophages appear to malfx
--untreatable except by lung transplantation

What are the signs and symptoms of idiopathic pulmonary fibrosis?
--dyspnea on exertion (DOE)
--non-productive cough
--crackles in lung
--late: cor pulmonale, clubbing of nails

What may be seen in a high resolution CT of the bases and periphery of lungs with IPF?
--small cystic lesions-->honey-comb appearance

What test is needed to make a diagnosis of IPF?
biopsy

What causes sarcoidosis?
nobody knows

Who gets sarcoidosis most?
--African Americans and those of Northern European descent, aged 20-40

How does sarcoidosis usually get diagnosed?
when it is seen incidentally on a chest x-ray, because it is mostly asymptomatic until onset of dyspnea, late

What do 90% of sarcoid pts with lung involvement have?
hilar adenopathy

What lab abnormalities are found in sarcoidosis?
--hypercalcemia
--elevated angiotensin converting enzyme

Why is there elevated calcium?
--alveolar macrophages in sarcoid pts can synthesize calcitriol, the most active form of vitamin D
(Can other people's macrophages do this????)

What are the three elements used to diagnose sarcoidosis?
--noncaseating granulomas
--hilar LAD
--hypercalcemia

What are a few other things that can be found in sarcoidosis?
--LN enlargement 25-50%
--skin manifestations such as erythema nodosum 25%
--uveitis 25% (red eye, photophobia, ciliary injection, diminished vision)
--glaucoma dt granulomas in uveal tract
--heptatic granulomas 70%
--cardiac involvement (when present kills 50%)
--adenopathy and infiltrates may spontaneously disappear
--may also be present for decades without symptoms

What is Goodpasture's syndrome?
--thankfully rare
--an auto-immune dz w/ anti-glomerular basement membrane antibodies-->disrupts alveolar basement membrane-->alveoli fill with blood
--presents with hemoptysis and hematuria
--type II hypersensitivity reaction
--named for American pathologist Dr Ernest Goodpasture, described dz in 1919

What treatments are offered for Goodpasture's?
--glucocorticoids
--cyclophosphosphamide
--plasmapheresis
--renal transplantation if lungs not involved
--may resist all Tx and pt die in days/weeks

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