Definition of Idiopathic

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Definition of Idiopathic

Idiopathic: Of unknown cause. Any disease that is of uncertain or

unknown origin may be termed idiopathic. For example, acute

idiopathic polyneuritis, diffuse idiopathic skeletal hyperostosis,

idiopathic pulmonary fibrosis, idiopathic scoliosis, etc.

From the New Latin idiopathia (primary disease), from the Greek

idiopatheia, from idio-, from idios (one's own, personal) + -

patheia, -pathic (feeling, suffering).

Nosology

From Wikipedia, the free encyclopedia

Nosology (in Greek Nosos = Disease) is a branch of medicine that

deals with classification of diseases.

Diseases can be classified by etiology (cause), pathogenesis

(mechanism in which the agent causes disease), or by symptom.

Alternatively, diseases can be classified according to the organ

system they involve, but this is often complicated as many diseases

affect multiple organs.

One of the main problems with nosologies is that diseases often

cannot be defined and classified clearly especially when

pathogenesis or causality is not known. So, diagnostic terms often

are in fact only symptoms or sets of symptoms (syndromes).

http://www.mayoclinic.com/health/interstitial-lung-

disease/DS00592/DSECTION=3

Interstitial lung disease

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The lungs

Each time you inhale, air travels to your lungs through two major

airways called bronchi. Inside your lungs, the bronchi subdivide

like the roots of a tree into a million smaller airways

(bronchioles) that finally end in clusters of tiny air sacs

(alveoli) — about 300 million in each lung. Within the walls of the

air sacs are small blood vessels (capillaries) where oxygen is added

to your blood and carbon dioxide — a waste product of metabolism —

is removed.

In interstitial lung disease, the walls of the air sacs may become

inflamed, and the tissue (interstitium) that lines and supports the

sacs becomes increasingly scarred. Normally, the air sacs are highly

elastic, expanding and contracting like small balloons with each

breath. But scarring (fibrosis) causes the thin, interstitial tissue

to become stiffer and thicker, making the air sacs less flexible.

Instead of being soft and elastic, scarred air sacs have the texture

of a dry sponge, which makes it more difficult to breathe and harder

for oxygen to enter your bloodstream.

Scarring in interstitial lung disease seems to occur when an injury

to your lungs triggers an abnormal healing response. Ordinarily,

your body generates the right amount of tissue to repair damage. But

in interstitial lung disease, the repair process goes awry,

producing excess scar tissue that increasingly interferes with lung

function.

One disorder, many causes

Because interstitial lung disease has a wide range of causes,

determining the reason for an initial injury to lung tissue can be

difficult. Some of the many possible precipitating factors include:

Infections. These include viral infections such as cytomegalovirus,

a particular problem for people with compromised immune systems;

bacterial infections, including pneumonia; fungal infections such as

histoplasmosis; and parasitic infections.

Occupation and environmental factors. Long-term exposure to a number

of toxins or pollutants can lead to serious lung damage. Workers who

routinely inhale silica dust (silicosis), asbestos fibers

(asbestosis) or hard metal dust are especially at risk of

debilitating lung disease. So are people exposed to certain chemical

fumes — sulfuric acid, for example — and ammonia or chlorine gases.

But chronic exposure to a wide range of substances, many of them

organic, also can damage your lungs. Among these are grain dust,

sugar cane, and bird and animal droppings. Other substances, such as

moldy hay, can be a problem when they cause a hypersensitivity

reaction in the lungs (hypersensitivity pneumonitis). Even bacterial

or fungal overgrowth in poorly maintained humidifiers and hot tubs

can cause lung damage.

Radiation. A small percentage of people who receive radiation

therapy for lung or breast cancer show signs of lung damage months

or sometimes years after the initial treatment. The severity of the

damage depends on how much of the lung is exposed to radiation, the

total amount of radiation administered, whether chemotherapy also is

used and the presence of underlying lung disease.

Drugs. Nearly 50 drugs can damage the interstitium of the lungs,

especially chemotherapy drugs, medications used to treat heart

arrhythmias and other cardiovascular problems, certain psychiatric

medications, and some antibiotics.

Other medical conditions. Interstitial lung disease can occur with

other disorders. Often, those conditions don't directly attack the

lungs, but instead involve systemic processes that affect tissue

throughout the body. Among these are connective tissue disorders and

hematological diseases, including systemic lupus erythematosis,

rheumatoid arthritis, dermatomyositis, polymyositis, Sjogren's

syndrome and sarcoidoisis.

Idiopathic pulmonary fibrosis: When the cause isn't known

Although doctors can determine why some people develop interstitial

lung disease, in most cases the cause isn't known. Disorders without

a known cause are considered a subset of interstitial lung disease

and are grouped together under the label idiopathic pulmonary

fibrosis or idiopathicinterstitial lung disease. Although the

idiopathic diseases have certain features in common, each also has

unique characteristics.

Usual interstitial pneumonitis is the most prevalent of the

idiopathic interstitial lung diseases. Accounting for more than half

of all cases, it's so common that the terms " usual interstitial

pneumonitis " and " idiopathic pulmonary fibrosis " are often used

interchangeably. Because usual interstitial pneumonitis develops in

patches, some areas of the lungs are normal, others are inflamed and

still others are marked by scar tissue. The disease affects twice as

many men as women and usually develops between the ages of 40 and 70.

Although the names are nearly identical, pneumonitis is not the same

as pneumonia. Pneumonitis is lung inflammation without infection,

whereas pneumonia is lung inflammation that results from infection.

In addition, pneumonia is generally limited to one or two areas of

the lungs, but pneumonitis involves all five lobes — two in the left

lung and three in the right.

Other, less common types of idiopathic pulmonary fibrosis include

nonspecific interstitial pneumonitis, bronchiolitis obliterans with

organizing pneumonia (BOOP), respiratory bronchiolitis-associated

interstitial lung disease, desquamative interstitial pneumonitis,

lymphocytic interstitial pneumonitis and acute interstitial

pneumonitis.