Restrictive lung diseases: Pathology review

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Case study0:00–1:11

While on your rounds, you see two individuals. First is Alicia, a 28 year old African American individual who comes in with progressive shortness of breath and cough.
She also mentions that she lost weight in the past six months and that she had tuberculosis a few years ago, examination reveals painful red skin lesions on each side of her nose and the anterior surface of both legs along the tibia.
The rest of the examination was normal. Next, you see a 65 year old male named Richard who presents with gradually progressive dyspnea on exertion and dry cough.
He has no history of underlying lung disease or other relevant symptoms. On examination, there was nail clubbing but no other signs that could suggest a particular etiology like pneumonia or COPD pulmonary function tests were performed in both cases showing signs of a restricted pattern, including a significant reduction in forced vital capacity, both seem to have some type of restrictive lung disease.

Physiology1:11–3:29

But first, a bit of physiology, the lung is compliant, meaning that it can expand and contract because its connective tissue is made up of proteins like elastin and collagen compliance is defined as the volume change produced by a change in the distending pressure.
And it is expressed as the ratio of delta V, the change in volume to delta P, which is the change in pressure. In other words, the higher the compliance, the easier it is for the lungs to expand.
In contrast, the lungs tendency to collapse and push the air back out is called elastic recoil, which is balanced by the outward pole of the chest wall.
Now remember that breathing also involves the structures around the lungs like the ribs, intercostal muscles, diaphragm or pleura during inhalation.
The diaphragm and intercostal muscles contract to pull the ribs up and out and expand the chest cavity. This creates a vacuum that pulls the lungs open to allow air in which eventually reaches the alveoli and specifically a thin membrane called the respiratory membrane where gas exchange occurs, air is then expelled by exhalation when the diaphragm and intercostal muscles relax to allow the chest wall to fall and return the chest cavity to normal.
Ok. So, restrictive lung diseases are a group of conditions in which inhalation fills the lungs far less than normal.
There are two types of restrictive lung diseases, diffuse parenchymal lung diseases and extrapulmonary lung diseases. In diffuse parenchymal lung diseases or DPL LDS previously called interstitial lung diseases.
The lung tissue itself is damaged. The result is a fibrotic rigid lung with reduced compliance and increased recoil that won't easily allow air to enter during inhalation, thereby reducing lung volumes on your test.

DPLD3:29–4:06

If you see graphs or questions mentioning dramatically decreased compliance, you should think of DP LDS since a reduced delta V over delta P ratio is the hallmark of pulmonary fibrosis in the extrapulmonary type.
Something else besides the lungs interferes with the breathing mechanics and prevents chest expansion and lung filling. For example, in scoliosis, because the spine is bent sideways, it can push on the lung on the affected side, impairing lung expansion and filling.
Generally, these abnormalities result in a few characteristic changes in pulmonary function tests or PFT S like spirometry and plethysmography.

Pulmonary Function Tests4:06–10:07

Spirometry is when you breathe into a tube attached to a machine called a spirometer, which measures the amount of air you breathe in and out and how quick you do it.
Plethysmography is when you are placed inside a sealed chamber and asked to breathe through a mouthpiece, which measures the pressure generated by your breathing to calculate the amount of air inside your lungs.
Ok. So in restrictive lung diseases, first, there's a decrease in forced vital capacity or FVC, which is the air exhaled forcefully after taking a deep breath, second, residual volume or RV decreases as well.
And it is the air left in the lungs after exhaling as hard as possible RV. And any lung capacity that includes RV cannot be measured by spirometry because it can't be breathed out even if the person tries to.
And this is why plethysmography is necessary. Third, there is also a reduction in total lung capacity or TLC calculated by adding FVC to RV.
Now, fourth, there's also a decrease in functional residual capacity or FRC, which is the volume of air that remains in the lungs after normal expiration FRC can also be calculated by adding RV to expiratory reserve or the air that can still be breathed out after normal expiration.
Fifth, there is a decrease in forced expiratory volume in one second or F EV. One which is the air exhaled with maximum effort in the 1st 2nd.
And finally, the F EV one over FVC ratio which is normally between 0.7 and 0.8 usually stays about the same because both volumes decrease proportionally.
One particularity you might come across is that the ratio can increase if FVC is reduced more than F EV. One, this can happen in some DP LDS where there is increased elastic recoil allowing air to be pushed out faster during the 1st 2nd of expiration.
Now, besides the typical PFT changes, most DPL LDS are also marked by a decrease in the lungs, diffusing capacity for carbon monoxide or DLCO, which is a measure of how well gasses are transferred between the lungs and the blood.
The decrease occurs because in DPL D, there is a thickened fibrotic respiratory membrane. So, gasses have a hard time passing through it.
Another high yield fact to know is that because less oxygen makes it into the bloodstream. The result is an elevated arterial alveolar or a a gradient, which is the difference between the partial pressure of oxygen in the alveoli written as P big A two and the arterial partial pressure of oxygen written as P little A two in time because the lung is damaged and feeling impaired.
Some areas of the lung will receive less oxygen than others. But at the same time, blood flow will stay the same throughout the lungs.
This is called a ventilation perfusion mismatch. And it can lead to hypoxemia.
Mostly because there's less oxygen available for blood to pick up. Hypoxemia is also made worse by an intrapulmonary shunt, which is when the pulmonary arterial start to constrict to adapt to hypoxemia, effectively shuttling or diverting blood away from the areas that don't receive any oxygen to the ones that do.
But if the damage is widespread, then it can lead to vasoconstriction of pulmonary arterioles which causes pulmonary hypertension.
That makes it hard for the right ventricle to pump out blood, causing the right ventricle to hypertrophy. A process called Cor Pulmonale.
Another high yield concept is how restrictive lung disease can change the flow volume loop, which is used to show airflow on the Y axis as it relates to lung volume on the X axis.
So imagine taking the deepest breath you can and then exhaling it out as forcefully as possible. In other words, the volume you're gonna exhale is the forced vital capacity and what will be left after maximal expiration inside the lung will be the residual volume.
And these two combined give us the total lung capacity. Now, since in most cases of restrictive lung disease, the residual volume and total lung capacity are decreased, the loop will typically show a shift to the right.
Now. Another thing to keep in mind is that in healthy people, airflow is slower at low lung volumes because elastic recoil decreases proportionately with lung volumes.
Low volumes are also associated with high airway resistance because the deflated lungs exert little radial traction on the conducting airways.
Radial traction is the force exerted by the lung parenchyma to keep the airways open. By contrast, it's important to understand that those with restrictive pulmonary diseases have low lung volumes.
But airflow is actually higher than normal, mostly because both elastic recoil and radial traction are increased. Usually due to the fibrotic pulmonary interstitium full of collagen.

Causes10:07–11:21

Let's now talk about the main causes of restrictive lung diseases. Diffuse parenchymal lung diseases or DP LDS are conditions that affect the interstitium, the alveoli, the respiratory membrane as well as the blood vessels and pleura DP LDS can be broadly classified into two categories.
First, there are those with unknown cause which can be subclassify into granulomatous diseases like sarcoidosis and hypersensitivity, pneumonitis.
Occupational exposures also called pneumoconiosis like asbestosis, silicosis, berylliosis, and coworkers, pneumoconiosis and miscellaneous diseases like rheumatoid arthritis, granulomatosis with polyangiitis, good Pastor syndrome, pulmonary Langerhans cell histiocytosis and drug toxicity.
And second, there are those with an unknown cause, mostly represented by idiopathic pulmonary fibrosis. To start with granulomatous lung diseases.

Granulomatous Pathology11:21–15:02

Besides sarcoidosis and hypersensitivity, pneumonitis also include contact dermatitis and the reactions resulting from the tuberculin and candida extract skin tests.
Now, these are usually a result of a type four hypersensitivity reaction which is also called a delayed type hypersensitivity because it takes 2 to 3 days to develop.
This is a cell mediated immune response triggered by antigens. The antigen causes a chain reaction that is frequently tested.
So first, the antigen gets picked up by an antigen presenting cell or a PC like a dendritic cell or an alveolar macrophage.
The A PC then presents the antigen to a CD four positive T helper cell or T cell and at the same time starts to secrete interleukin 12 or IL 12, which binds to the il 12 receptor of a CD four positive T cell causing it to differentiate into at helper type one cell.
This stimulates T helper type one cells to start secreting il two, which helps both it and other T cells in the area proliferate as well as secrete interferon gamma which activates phagocytes like macrophages.
The activated macrophages now called epithelioid macrophages because they have lots of pink cytoplasms similar to squamous epithelial cells are attracted to the site of antigen exposure.
Here, they surround the antigen forming the center of a ball like nodule called a granuloma, which is meant to wall off the antigen and prevent it from spreading on the periphery of the granuloma.
There are CD four positive th cells and multinucleated giant cells which are formed when several activated macrophages fuse together.
The giant cells are also called Long Han's giant cells and have multiple nuclei which are arranged peripherally in the shape of a horseshoe.
Another particularity of the Hans giant cells is that they contain cytoplasmic inclusions called Shaman bodies which are made of calcium and protein deposits.
There are also asteroid bodies that look like tiny stars which are likely pieces of cytoskeleton or lipids. Keep in mind that these longhorn cells are especially common in sarcoidosis.
Now, there are two types of granulomas caseating which are associated with central necrosis and seen in infectious etiologies like tuberculosis and noncaseating which have no central necrosis and are seen with autoimmune diseases like sarcoidosis, hypersensitivity, pneumonitis or Crohn's disease.
Ok. So finally, if the antigen is removed, then the lungs heal up quickly.
However, if exposure or the antigen persists, fibroblasts are attracted to the site of injury where they start the process of scarring by depositing fibrin, resulting in a fibrotic lung that is stiff and less compliant, which as a consequence limits lung expansion and volumes.
Now that we've looked at the general pathology, let's look at the first disease, sarcoidosis. The precise trigger of this condition isn't known, but there are some associated risk factors that are frequently tested.

Sarcoidosis15:02–21:08

Genetic risk factors include being of African descent and having a family member with sarcoidosis and younger females are more commonly affected.
Environmental risk factors include a prior infection with mycobacterium tuberculosis and Borrelia burgdorferi. However, in sarcoidosis, these pathogens are long gone when the autoimmune damage sets in basically dendritic cells.
A type of A PC go haywire without the presence of a specific pathogen that the body is trying to destroy attracting T cells and macrophages to a particular spot of healthy tissue where they form granulomas.
And because it is a systemic disease, sarcoidosis can involve nearly every organ even if it usually involves hilar lymph nodes which are located near the point where the bronchi meets the lungs.
Sarcoidosis is usually asymptomatic or it can cause unspecific signs and symptoms like fever, weight loss, fatigue and enlarged lymph nodes.
Because it's a systemic disease. There can also be more specific symptoms depending on which part of the body is affected.
If the lungs are affected, it can cause shortness of breath, coughing and hypoxemia. If the skin is involved, it can lead to nodules called erythema nodosum.
This is very high yield. So remember that they typically develop on the lower legs along the tibia.
These nodules are caused by inflammation of fat within the skin layer and they're red, hard and painful. Another possible skin lesion is lupus pernio, which refers to red to purple skin lesions on the face resembling those found in lupus.
When the eye is involved, sarcoidosis can also cause uveitis which is inflammation in the pigmented layer of the eye beneath the cornea and sclera.
The heart can also be affected leading to restrictive or dilated cardiomyopathy. When the joints are involved, sarcoidosis can cause rheumatoid arthritis like arthropathy as suggested by tender warm swollen joints with limited mobility.
Another high yield fact to remember is that in many granulomatous diseases, especially in sarcoidosis, individuals can also develop hypercalcemia due to the enzyme.
One alpha hydroxylase being released by alveolar macrophages. The enzyme converts the Vitamin D precursor to its active form called calcitriol, which in turn increases intestinal absorption of calcium and bone resorption causing hypercalcemia.
Some signs of hypercalcemia include diminished deep tendon reflexes, skeletal muscle weakness and in some cases depression and stupor.
The liver is also involved in up to 75% of individuals with sarcoidosis. And this may present with hepatomegaly, abdominal pain, cirrhosis or cholestatic liver disease with jaundice.
And finally, the condition can affect the brain causing neuro sarcoidosis. The most important sign of neurosarcoidosis is bells, palsy, a type of facial paralysis that makes it impossible to control the facial muscles on the affected side.
This can manifest as muscle twitching weakness or total loss of the ability to move one side of the face. Besides a restrictive pattern on PFTs, sarcoidosis diagnosis also includes a chest X ray or CT scan the most common findings on both tests and in real life are bilateral hilar or mediastinal lymphadenopathy and coarse reticular opacities due to interstitial infiltration by inflammatory cells.
And as the condition evolves a honeycombing pattern. Usually in the upper lobes, blood tests might reveal high levels of calcium and an increased level of angiotensin converting enzyme or ace which is produced by T cells.
Another helpful clue is finding an elevated CD four positive to CD eight positive ratio in the fluid obtained by bronchoalveolar lavage.
In that procedure, a bronchoscope is passed through the mouth or nose and into the lungs where fluid is squirted out, recollected and examined the ratio increases because the immune reaction causes CD four positive T cells to accumulate in the interstitium and alveoli.
Whereas the CD eight positive T cell count stays the same. One final thing to know about sarcoidosis is that a transesophageal lung biopsy showing scattered noncaseating granulomas might be needed to confirm the diagnosis.
Needle biopsy of the liver can also be used to check for the presence of scattered noncaseating granulomas. Most people with sarcoidosis don't usually need treatment because symptoms resolve spontaneously within a few weeks with complete remission occurring within a few years.
But if there are severe symptoms, steroids can help control the inflammatory response. Ok.
Next up, we have hypersensitivity pneumonitis, which is when an inhaled antigen causes an excessive immune reaction in the lung.

Hypersens. Pneumonitis21:08–25:47

It can be caused by many organic antigens from coffee bean dust to moldy sugarcane to bacterial spores in the mist from hot tubs.
And the resulting disease is often named for the profession at risk. For instance, the farmer's lung is caused by the spores of actinomycetes that live in moist newly harvested hay malt.
Worker's lung is from Aspergillus spores from moldy barley pigeon breeder lung is caused by breathing and proteins from bird poop or feathers.
But other animal proteins can also cause the disease. Now, unlike most granulomatous diseases, hypersensitivity, pneumonitis can trigger both a type three hypersensitivity reaction.
In which case, it's acute and a type four hypersensitivity reaction. In which case, it's chronic.
Basically, once antigen reaches the alveoli, it is picked up by dendritic cells or alveolar macrophages which take it to the nearest lymph node where they present it to th one cells.
Th one cells then activate B cells to produce immunoglobulin g antibodies that go into the bloodstream where they meet the antigens that cross over from the alveoli and form immune complexes.
This leads to acute hypersensitivity, pneumonitis, which is a type three hypersensitivity reaction and is immune complex mediated.
Specifically these complexes then get deposited in the basement membrane of the pulmonary capillaries, activating the complement system and attracting neutrophils to the site.
Neutrophils degranulate, meaning they dump lysosomal enzymes and reactive oxygen species into the area leading to inflammation and necrosis of the capillaries as well as nearby alveoli.
If exposure to the trigger continues or if the acute response is unsuccessful, it leads to chronic hypersensitivity pneumonitis, which is a type four hypersensitivity reaction with a granuloma formation.
The signs and symptoms of acute hypersensitivity pneumonitis include fever, shortness of breath, cough, chest tightness and headache, which typically develop within hours after exposure and resolve gradually within 12 hours to several days.
Following exposure removal, chronic hypersensitivity, pneumonitis has an insidious onset, meaning symptoms develop slowly and worsen over months to years.
Eventually, this leads to sustained shortness of breath and in severe cases, respiratory failure. Besides a restrictive pattern on PFT S diagnosis is based on a chest X ray or CT showing numerous poorly defined small opacities throughout both lungs, sometimes with sparing of the aps and base occasionally ground glass opacification, which is an area of increased opacity with preserved bronchial and vascular markings can be the predominant or only finding a bronchoalveolar lavage might reveal a high number of lymphocytes and mast cells in the lavage fluid.
A lung biopsy can also be performed and it can show noncaseating granulomas around the bronchioles and lymphocyte infiltration in the alveolar walls.
Lastly, diagnosis involves identification of the environmental trigger via an inhalation challenge which is when a person is exposed to the possible trigger and monitored to see if they develop symptoms because the condition is reversible.
In early stages. If the stimulus is avoided, treatment consists of eliminating the cause, either by avoiding the environment, altering the environment or wearing personal protective equipment, steroids can be used to help with symptoms but they don't help deal with the underlying issue.
The second category consists of pneumoconiosis which are diseases caused or made worse by the particles. A person is exposed to within the workplace like asbestos and silica or coal dust.

Pneumoconiosis25:47–27:32

Now keep in mind that normally alveolar macrophages protect the alveoli by eating all foreign particles under two micrometers that reach them by a process called phase tosis.
In pneumoconiosis, macrophages fail to eat these inhaled particles because they are hard to digest or toxic. This causes some of them to die.
Activating the remaining macrophages which start to release inflammatory cytokines and growth factors, cytokines, damage the lungs and cause inflammation, attracting even more macrophages and fibroblasts that proliferate and synthesize collagen.
In order to control the damage in time, if the inflammatory response persists the collagen released by fibroblasts into the interstitial spaces hardens resulting in scar tissue that causes alveolar walls to thicken.
So remember that unlike the previous two disorders, pneumoconiosis is not always associated with a hypersensitivity reaction.
Pneumoconiosis can also increase the risk of Kaplan Syndrome, which is a combination of rheumatoid arthritis and pneumoconiosis with intra pulmonary nodules.
This is most likely due to rheumatoid arthritis tendency to alter how a person's immune system responds to foreign materials for the causative agents.

Asbestosis27:32–30:39

Asbestos belongs to a family of minerals called silicates, typically used as materials in shipbuilding plumbing, roofing and the textile industry.
The risk of getting the disease depends on the duration and intensity of exposure and the type length and thickness of inhaled fibers.
Actually, you should know that people exposed to asbestos also have a high risk of mesothelioma, which is a type of aggressive cancer that originates from the mesothelium, which is a thin membrane made of epithelial cells that lines the pleural cavity.
A high yield concept to keep in mind is that they have an even higher risk of bronchogenic carcinoma. Asbestosis is initially asymptomatic but can sometimes cause progressive dyspnea, non productive cough and fatigue, advanced asbestosis may cause hypoxemia, nail clubbing, dry crackles at the base of both lungs and in severe cases, symptoms of core pulmonale like chest pain, tachypnea and exertional dyspnea.
Diagnosis is based on a history of exposure to asbestos, a restrictive pattern on PFT S and chest X ray or high resolution CT which might show reticular bilateral opacities in the lower lobes.
This can be remembered by the mnemonic asbestos is from the roof because asbestos was common in insulation but affects the base, which means lower lobes of the lungs.
If pleura is affected, exudative effusion and pleural plaques with calcification are also common pleural plaques are areas of the pleura that are thickened by collagen deposits.
And more importantly, virtually pathognomonic of exposure to asbestos on an X ray. They are seen as opacities that present the incomplete border sign, which is when the inner margin of the opacity is well defined because it is tangential to the X ray beam, but the outer margin is barely visible on a sputum sample obtained by bronchoalveolar lavage and colored using a Prussian blue stain asbestos bodies also called ferruginous bodies are seen as golden brown fusiform rods or as having a dumbbell shape with multiple segmentation.
No specific treatment exists early detection of complications like hypoxemia and right ventricular failure is vital. While pulmonary rehabilitation consisting of exercise, training, health education and breathing techniques can be helpful in reducing symptom severity.
The next type of pneumoconiosis is silicosis. This condition is characterized by nodular pulmonary fibrosis, secondary to inhalation of silica dust, silica dust.

Silicosis30:39–33:42

More specifically crystalline silica is found in rocks, sand, gravel and clay, which is why silicosis is associated with those who work in sandblasting, foundries and mines moving on.
There are two high yield particularities. To note regarding its pathophysiology.
First, silica is thought to disrupt the macrophage, phagolysosome, impairing the macrophages killing ability. It's important to remember that defense against mycobacteria.
The bacteria that causes tuberculosis is especially impaired. So, individuals with silicosis are more susceptible to developing tuberculosis.
And second, when the silica containing macrophages die, they release the silica particles into the interstitial tissue around the small bronchioles causing the formation of the pathognomonic silicotic nodules.
These nodules initially contain inflammatory cells and fibroblasts, dense patches of collagen fibers and scattered birefringent particles of silica dust as the nodules mature their center becomes a dense ball of fibrotic scar with a classic onion skin appearance, which is surrounded by an outer layer of inflammatory cells.
If exposure is terminated, the nodules don't evolve or compromise lung function. But if it persists, the nodules merge together and cause progressive fibrosis.
Silicosis initially causes mild dyspnea on exertion. But as fibrosis progresses, it can lead to severe dyspnea, hypoxemia, pulmonary hypertension and respiratory impairment diagnosis is based on a history of silica exposure, a restrictive pattern on PFTs and chest X ray or CT findings.
The most common findings are nodular opacities in both lungs and the classic eggshell calcification of hilar lymph nodes usually affecting the upper lobes.
This can be remembered by the mnemonic silica is from the base or the earth, but it affects the roof which are the upper lobes.
A node biopsy can confirm the diagnosis by showing birefringent particles of silica surrounded by fibrosis. No effective treatment exists except supportive care and for severe cases, lung transplantation.
Next, chronic borreliosis is both a chronic occupational and granulomatous lung disease characterized by systemic noncaseating granulomas caused by beryllium exposure.

Berylliosis33:42–36:28

Chronic berylliosis is often the result of repeated exposure to beryllium and it is distinct from acute beryllium poisoning which became rare following occupational exposure limits.
Now, beryllium is a metal that is used in aerospace and manufacturing industry for items like cars, computers, golf clubs and electrical equipment.
The metal itself is safe but the beryllium dust or fumes that result from its processing is highly toxic. In those susceptible, the substance triggers a type four hypersensitivity reaction with mononuclear cell infiltrates and non caseating granuloma formation in the organs where beryllium has deposited, especially the lungs, intrathoracic lymph nodes and skin.
In some. After the initial exposure, the lungs can actually become sensitized to beryllium and they will be asymptomatic in others.
Symptoms may develop within months of first exposure or even 30 years after exposure has ceased. Typically, these consist of progressive dyspnea, cough and fatigue.
Some people can also lose weight and have night sweats. Diagnosis includes a history of beryllium exposure, a restrictive pattern on PFTs and establishing beryllium sensitivity using the beryllium lymphocyte proliferation test.
The test uses peripheral blood or fluid from a bronchoalveolar lavage and lymphocytes cultured with beryllium sulfate cells are then counted and those with an elevated number of cells are considered abnormal chest X ray and CT can detect nonspecific signs like nodular opacities in the mid and upper lung zones.
Frequently with hilar and mediastinal adenopathy. There is no cure for borreliosis.
However, there are nonspecific approaches that can reduce symptoms and slow the progression of disease. These include stopping exposure to the substance giving supplemental oxygen and oral corticosteroids.
In those with acute symptoms and pulmonary rehabilitation and lastly coal workers, pneumoconiosis or CWP, also known as black lung disease or coal miners lungs is characterized by lung damage caused by exposure to coal dust the condition is common in coal miners who develop the disease after being exposed to coal dust for more than 20 years.

CWP36:28–38:56

Air pollution particles can also lead to a similar but asymptomatic condition called anthracosis, which is typically found in many urban dwellers exposed to sooty air.
Now, something specific to CWP is that as macrophages eat up the inhaled coal, they become laden with carbon and form 1 to 2 millimeters, nodular aggregations supported by a fine collagen network called coal macules.
These structures are the pathognomonic feature of CWP and tend to occur around the initial site of coal dust accumulation, which is the upper regions of the lungs around respiratory bronchioles because they cause pulmonary inflammation.
They are also surrounded by focal emphysema which develops as bronchial walls weaken and dilate fibrosis can occur but is usually limited to areas adjacent to coal macules.
In severe cases, the macules can merge to form coal nodules which they themselves can coalesce to form black rubbery parenchymal masses usually in the upper posterior lung fields.
CWP does not usually cause symptoms. Most chronic pulmonary symptoms in coal miners like cough, dyspnea and chest pain are caused by other conditions such as industrial bronchitis due to coal dust or coincident emphysema due to smoking.
Diagnosis is based on a history of coal exposure, a restrictive pattern on PFT S and A chest X ray showing small rounded nodular opacities typically affecting the upper lobes.
Treatment is generally supportive. The most important part being limiting exposure to coal dust and pulmonary rehabilitation.
And the final category belongs to miscellaneous causes of restrictive lung disease. Now, there's a lot to talk about here.

Miscellaneous Causes38:56–39:50

But the bottom line is that many systemic diseases like rheumatoid arthritis, granulomatosis with polyangiitis. Good Pastor syndrome and pulmonary Langerhans cell histiocytosis can cause lung damage resulting in pulmonary fibrosis by a variety of mechanisms.
Drugs like the antiarrhythmic amiodarone, the antibiotic, nitrofurantoin or chemotherapeutic agents like methotrexate bleomycin and busulfan can also result in pulmonary fibrosis with symptoms similar to those of the rest of DPL LDS moving on to restrictive lung diseases without a known cause.

IPF39:50–42:59

Idiopathic pulmonary fibrosis is characterized by repeated cycles of lung injury and healing resulting in excess scar tissue in the interstitial tissue of the lung.
Now, the most important thing to note is that the trigger is unknown and that the condition usually presents in individuals with no history of pulmonary diseases.
However, there are some known risk factors including old age, male and tobacco smoking. Once the process starts.
The fundamental problem is that type two pneumocytes over proliferate. Type two pneumocytes line the alveolar wall along with type one pneumocytes, they secrete surfactant and have the unique ability to proliferate whenever the alveoli are injured.
Myofibroblasts, which are cells that secrete collagen over proliferate too and to make matters worse, they don't undergo apoptosis as they should at the end of the repair process.
Instead, they continue to make even more collagen. And as collagen accumulates and hardens.
It causes the lungs to stiffen and the respiratory membrane to thicken, leading to the changes seen in DP LDS. Another complication that can occur is traction, bronchiectasis, which is irreversible dilation of bronchi and bronchioles caused by fibrosis, pulling apart the surrounding parenchyma.
Individuals are usually asymptomatic in the early stages. But because idiopathic pulmonary fibrosis is a progressive process, they can quickly develop symptoms that impair normal daily activities.
Problems with oxygenation and ventilation can cause dry coughing and shortness of breath as well as cyanosis and digital clubbing over time.
It can lead to significant respiratory failure as more of the healthy functional tissue is lost. Diagnosis of idiopathic pulmonary fibrosis can be made using PFTs which can show signs of restrictive lung disease and chest ct where the most common finding is the honeycomb pattern associated with pulmonary fibrosis.
Diagnosis can be confirmed by lung biopsy showing dense fibrosis, fibroblast proliferation and cyst formation. In order to diagnose idiopathic pulmonary fibrosis, it's necessary to first rule out other potential causes of pulmonary fibrosis.
Treatment options include supplemental oxygen and anti fibrotic medications which generally slow the progression of the disease rather than stopping it.
Unfortunately, the only definitive treatment available currently for severe situations is a lung transplant and to conclude extrapulmonary restrictive lung diseases are those conditions that interfere with the structures involved in the breathing mechanisms because the lungs are healthy.

ELD42:59–44:41

Both the diffusing capacity and a a gradient are normal, but the volume changes seen in the other restrictive pulmonary diseases are present.
Now, we can divide the extrapulmonary causes into two main categories. First are the ones that cause weakness of the respiratory muscles.
These include polio, myasthenia, Gravis, Guillain Barre syndrome. And second, there are those characterized by structural abnormalities like scoliosis and morbid obesity, these impair inhalation by acting as an obstacle in lung expansion causing a decrease in inhalation, lung volumes.
Another example of this would be ankylosing spondylitis, a type of arthritis affecting the spine which restricts pulmonary expansion by causing fusion of the costo vertebral joints and ankylosis of the thoracic spine or by anterior chest wall involvement.
Symptoms depend on the underlying pathology but most individuals tend to present with short shallow breaths and pain while inhaling diagnosis is based on the clinical picture.
P FT S chest X ray and CT and specific diagnostic test for whatever is suspected of causing the ventilatory problem. All right.
As a quick recap, restrictive lung diseases are marked by impaired inhalation which causes a decrease in forced vital capacity, residual volume, total lung capacity and functional residual capacity.

Review44:41–46:20

The causes of restrictive lung disease can be divided into diffuse parenchymal lung diseases and extrapulmonary lung disease.
DP. LDS include sarcoidosis, a systemic autoimmune disease common in African American females, hypersensitivity pneumonitis which is a type three and type four hypersensitivity reaction due to an inhaled antigen pneumoconiosis which includes asbestosis, silicosis, chronic berylliosis and coworkers, pneumoconiosis where inhaled toxic particles can't be broken down by macrophages leading to chronic inflammation and impaired macrophage function.
And idiopathic pulmonary fibrosis, which results from increased scarring of the alveoli by an unknown cause extrapulmonary lung disease.
Can also have a restrictive pattern where the lung volumes and capacities are decreased but diffusion and the AA gradient is normal.
Common causes can be due to respiratory muscle weakness like myasthenia, gravis and Guillain Barre syndrome or due to structural abnormalities like morbid obesity and scoliosis.
Back to our cases. Alicia presents with progressive shortness of breath and cough, weight loss.

Summary46:20–47:19

And her P FT showed a restrictive pattern. Examination reveals painful red skin lesions on the sides of her nose and both legs.
This is erythema nodosum, which are a classic sign of sarcoidosis. Another clue is that she's a young female of African descent to confirm the diagnosis.
A chest X ray and biopsy can be done. Next.
Richard presents with gradually progressive dyspnea on exertion, nonproductive cough, nail clubbing. And his P FT showed a restrictive pattern.
Chest X ray showed honeycombing fibrosis, but that's not specific to any disease. Now, given his unspecific symptoms and the fact that he has no history of underlying pulmonary disease, we suspect he suffers from idiopathic pulmonary disease.