The morbidity associated with DIPNECH is due to the associated obstructive lung disease. The lung disease tends to be slowly progressive, but given enough time can lead to significant disability and require supplemental oxygen therapy. There have been reports of lung transplantation in the setting of end-stage DIPNECH.

Pregnancy has been reported to exacerbate LAM in some cases. However, the risk has not been rigorously studied. In a survey of 318 patients who indicated that they had had at least one pregnancy, 163 responded to a second survey focusing on lung collapse. A total of 38 patients reported a pneumothorax with pregnancy, consistent with an incidence of pneumothorax in pregnancy of at least 10% (38 of 318). In one third of patients, the pneumothorax during pregnancy led to the LAM diagnosis. Pneumothoraces were almost twice as frequent on the right as on the left, and four women presented with bilateral spontaneous pneumothorax. Most pneumothoraces took place during the second and third trimesters. This study and others suggest that pregnancy is associated with pleural complications in LAM patients. Few women with a known LAM diagnosis choose to become pregnant and patients in whom LAM is diagnosed during pregnancy rarely have baseline pulmonary function tests available, complicating resolution of this question.

LAM is almost completely restricted to women. While lung cysts consistent with LAM are reported in some men with tuberous sclerosis, very few of these men develop symptoms. The prevalence of LAM is estimated using data from registries and patient groups and is between 3.4-7.8/million women. The number of new cases each year is between 0.23-0.31/million women/year in the US, UK and Switzerland. The variation between countries and between adjacent states in the US, suggest that a significant number of women with LAM remain either undiagnosed or their symptoms are attributed to other diseases. Adult women with tuberous sclerosis are more likely to develop LAM than women without tuberous sclerosis. Cohorts of patients with tuberous sclerosis have been screened for LAM using CT scanning. In a retrospective study of adults with tuberous sclerosis, CT demonstrated lung cysts in 42% of 95 women and 13% of 91 men. In general, lung cysts were larger and more numerous in women than in men. In a further retrospective study of women with TSC who underwent CT scanning to detect LAM, 25% of those in their 20s had lung cysts whereas 80% of women in their 40s were affected, suggesting that the development of LAM is age dependent at least in tuberous sclerosis-related LAM. Although the prevalence of tuberous sclerosis at 1 in 6000 births is much greater than that of LAM, most pulmonary clinics see more cases of sporadic than tuberous sclerosis-LAM: probably due to a combination of low levels of screening for LAM in tuberous sclerosis and in many, the absence of symptoms.

Female sex and tuberous sclerosis are the only known risk factors. Although use of supplemental estrogen is not associated with development of LAM, one study suggested that use of estrogen-containing contraceptive pills was associated with earlier onset.

It occurs in more than 30% of women with tuberous sclerosis complex (TSC-LAM), a heritable syndrome that is associated with seizures, cognitive impairment and benign tumors in multiple tissues. Most LAM patients who present for medical evaluation have the sporadic form of the disease (S-LAM), however, which is not associated with other manifestations of tuberous sclerosis complex.

Mild cystic changes consistent with LAM have been described in 10–15% of men with TSC, but symptomatic LAM in males is rare. Sporadic LAM occurs exclusively in women, with one published exception to date. Both TSC-LAM and S-LAM are associated with mutations in tuberous sclerosis genes.

To date there have been no clinical trials to determine effective treatment for this disease. Some patients have been treated with somatostatin analogs. Although the cough associated with DIPNECH tends to diminish on this treatment, improvement in pulmonary function has not been clearly demonstrated. There are also reports of symptomatic treatment with long- and short-acting beta agonists. Although steroids, both oral and inhaled, have been used in the setting of DIPNECH, there is no clear improvement with this treatment.

It is not uncommon for typical carcinoids to arise within DIPNECH. Due to presence of these tumors, DIPNECH is classified as a pre-malignant condition. Although there have been reports of atypical carcinoids with local lymph node involvement, there are no reports of more aggressive neuroendocrine tumors, such as large cell neuroendocrine or small cell lung cancer, associated with DIPNECH. When isolated bronchial carcinoids are diagnosed, oncology guidelines recommend surgical resection with lymph node sampling. However, as multiple carcinoids may develop in the setting of DIPNECH, a more conservative approach is often considered to preserve lung function.

Asbestos can cause lung cancer that is identical to lung cancer from other causes. Exposure to asbestos is associated with all major histological types of lung carcinoma (adenocarcinoma, squamous cell carcinoma, large-cell carcinoma and small-cell carcinoma). The latency period between exposure and development of lung cancer is 20 to 30 years. It is estimated that 3%-8% of all lung cancers are related to asbestos. The risk of developing lung cancer depends on the level, duration, and frequency of asbestos exposure (cumulative exposure). Smoking and individual susceptibility are other contributing factors towards lung cancer. Smokers who have been exposed to asbestos are at far greater risk of lung cancer. Smoking and asbestos exposure have a multiplicative (synergistic) effect on the risk of lung cancer. Symptoms include chronic cough, chest pain, breathlessness, haemoptysis (coughing up blood), wheezing or hoarseness of the voice, weight loss and fatigue. Treatment involves surgical removal of the cancer, chemotherapy, radiotherapy, or a combination of these (multimodality treatment). Prognosis is generally poor unless the cancer is detected in its early stages. Out of all patients diagnosed with lung cancer, only 15% survive for five years after diagnosis.

IPF has been recognized in several breeds of both dogs and cats, and has been best characterized in West Highland White Terriers. Veterinary patients with the condition share many of the same clinical signs as their human counterparts, including progressive exercise intolerance, increased respiratory rate, and eventual respiratory distress.

Prognosis is generally poor.

The cause of IPF is unknown but certain environmental factors and exposures have been shown to increase the risk of getting IPF. Cigarette smoking is the best recognized and most accepted risk factor for IPF, and increases the risk of IPF by about twofold. Other environmental and occupation exposures such as exposure to metal dust, wood dust, coal dust, silica, stone dust, biologic dusts coming from hay dust or mold spores or other agricultural products, and occupations related to farming/livestock have also been shown to increase the risk for IPF. There is some evidence that viral infections may be associated with idiopathic pulmonary fibrosis and other fibrotic lung diseases.

Regardless of cause, UIP is relentlessly progressive, usually leading to respiratory failure and death without a lung transplant. Some patients do well for a prolonged period of time, but then deteriorate rapidly because of a superimposed acute illness (so-called "accelerated UIP"). The outlook for long-term survival is poor. In most studies, the median survival is 3 to 4 years. Patients with UIP in the setting of rheumatoid arthritis have a slightly better prognosis than UIP without a known cause (IPF).

ILD may be classified according to the cause. One method of classification is as follows:

1. Inhaled substances

- Inorganic

- Silicosis

- Asbestosis

- Berylliosis

- printing workers (eg. carbon bblack, ink mist)

- Organic

- Hypersensitivity pneumonitis

2. Drug-induced

- Antibiotics

- Chemotherapeutic drugs

- Antiarrhythmic agents

3. Connective tissue and Autoimmune diseases

- Rheumatoid arthritis

- Systemic lupus erythematosus

- Systemic sclerosis

- Polymyositis

- Dermatomyositis

4. Infection

- Atypical pneumonia

- Pneumocystis pneumonia (PCP)

- Tuberculosis

- "Chlamydia" trachomatis

- Respiratory Syncytial Virus

5. Idiopathic

- Sarcoidosis

- Idiopathic pulmonary fibrosis

- Hamman-Rich syndrome

- Antisynthetase syndrome

6. Malignancy

- Lymphangitic carcinomatosis

7. Predominantly in children

- Diffuse developmental disorders

- Growth abnormalities deficient alveolarisation

- Infant conditions of undefined cause

- ILD related to alveolar surfactant region

Respiratory disease is a common and significant cause of illness and death around the world. In the US, approximately 1 billion "common colds" occur each year. A study found that in 2010, there were approximately 6.8 million emergency department visits for respiratory disorders in the U.S. for patients under the age of 18. In 2012, respiratory conditions were the most frequent reasons for hospital stays among children.

In the UK, approximately 1 in 7 individuals are affected by some form of chronic lung disease, most commonly chronic obstructive pulmonary disease, which includes asthma, chronic bronchitis and emphysema.

Respiratory diseases (including lung cancer) are responsible for over 10% of hospitalizations and over 16% of deaths in Canada.

In 2011, respiratory disease with ventilator support accounted for 93.3% of ICU utilization in the United States.

Pulmonary fibrosis may be a secondary effect of other diseases. Most of these are classified as interstitial lung diseases. Examples include autoimmune disorders, viral infections and bacterial infection like tuberculosis which may cause fibrotic changes in both lungs upper or lower lobes and other microscopic injuries to the lung. However, pulmonary fibrosis can also appear without any known cause. In this case, it is termed "idiopathic". Most idiopathic cases are diagnosed as "idiopathic pulmonary fibrosis". This is a diagnosis of exclusion of a characteristic set of histologic/pathologic features known as usual interstitial pneumonia (UIP). In either case, there is a growing body of evidence which points to a genetic predisposition in a subset of patients. For example, a mutation in surfactant protein C (SP-C) has been found to exist in some families with a history of pulmonary fibrosis.

Diseases and conditions that may cause pulmonary fibrosis as a secondary effect include:

- Inhalation of environmental and occupational pollutants, such as metals in asbestosis, silicosis and exposure to certain gases. Coal miners, ship workers and sand blasters among others are at higher risk.

- Hypersensitivity pneumonitis, most often resulting from inhaling dust contaminated with bacterial, fungal, or animal products.

- Cigarette smoking can increase the risk or make the illness worse.

- Some typical connective tissue diseases such as rheumatoid arthritis, SLE and scleroderma

- Other diseases that involve connective tissue, such as sarcoidosis and granulomatosis with polyangiitis.

- Infections

- Certain medications, e.g. amiodarone, bleomycin (pingyangmycin), busulfan, methotrexate, apomorphine, and nitrofurantoin

- Radiation therapy to the chest

Five million people worldwide are affected by pulmonary fibrosis. A wide range of incidence and prevalence rates have been reported for pulmonary fibrosis. The rates below are per 100,000 persons, and the ranges reflect narrow and broad inclusion criteria, respectively.

Based on these rates, pulmonary fibrosis prevalence in the United States could range from more than 29,000 to almost 132,000, based on the population in 2000 that was 18 years or older. The actual numbers may be significantly higher due to misdiagnosis. Typically, patients are in their forties and fifties when diagnosed while the incidence of idiopathic pulmonary fibrosis increases dramatically after the age of fifty. However, loss of pulmonary function is commonly ascribed to old age, heart disease or to more common lung diseases.

Pulmonary diseases may also impact newborns, such as pulmonary hyperplasia, pulmonary interstitial emphysema (usually preterm births), and infant respiratory distress syndrome,

Interstitial lung disease (ILD), or diffuse parenchymal lung disease (DPLD), is a group of lung diseases affecting the interstitium (the tissue and space around the air sacs of the lungs). It concerns alveolar epithelium, pulmonary capillary endothelium, basement membrane, perivascular and perilymphatic tissues. It may occur when an injury to the lungs triggers an abnormal healing response. Ordinarily, the body generates just the right amount of tissue to repair damage. But in interstitial lung disease, the repair process goes awry and the tissue around the air sacs (alveoli) becomes scarred and thickened. This makes it more difficult for oxygen to pass into the bloodstream. The term ILD is used to distinguish these diseases from obstructive airways diseases.

In children, several unique forms of ILD exist which are specific for the young age groups. The acronym chILD is used for this group of diseases and is derived from the English name, Children’s Interstitial Lung Diseases – chILD.

Prolonged ILD may result in pulmonary fibrosis, but this is not always the case. Idiopathic pulmonary fibrosis is interstitial lung disease for which no obvious cause can be identified (idiopathic), and is associated with typical findings both radiographic (basal and pleural based fibrosis with honeycombing) and pathologic (temporally and spatially heterogeneous fibrosis, histopathologic honeycombing and fibroblastic foci).

In 2013 interstitial lung disease affected 595,000 people globally. This resulted in 471,000 deaths.

Alveolar lung diseases, are a group of diseases that mainly affect the alveoli of the lungs.

Sixty percent of people with acute interstitial pneumonitis will die in the first six months of illness. The median survival is 1½ months.

However, most people who have one episode do not have a second. People who survive often recover lung function completely.

Asbestosis is a chronic lung disease caused by scarring of lung tissue, which results from prolonged exposure to asbestos. It is defined as diffuse interstitial pulmonary fibrosis secondary to asbestos exposure. It initially affects the lung bases and usually manifests after 15 or more years from initial exposure. It occurs after high intensity and/or long-term exposure to asbestos. Asbestos-related fibrosis is progressive because it continues to progress in the lung even if no further asbestos is inhaled. The scar tissue causes the alveolar walls to thicken, reducing the lung capacity which leads to the patient experiencing shortness of breath (dyspnea). Sufferers are at an increased risk for heart failure and certain malignancies.

Many cases of restrictive lung disease are idiopathic (have no known cause). Still, there is generally pulmonary fibrosis. Examples are:

- Idiopathic pulmonary fibrosis

- Idiopathic interstitial pneumonia, of which there are several types

- Sarcoidosis

- Eosinophilic pneumonia

- Lymphangioleiomyomatosis

- Pulmonary Langerhans' cell histiocytosis

- Pulmonary alveolar proteinosis

Conditions specifically affecting the interstitium are called interstitial lung diseases.

Alveolar lung disease may be divided into acute or chronic. Causes of acute alveolar lung disease include pulmonary edema (cardiogenic or neurogenic), pneumonia (bacterial or viral), pulmonary embolism, systemic lupus erythematosus, bleeding in the lungs (e.g., Goodpasture syndrome), idiopathic pulmonary hemosiderosis, and granulomatosis with polyangiitis.

Chronic alveolar lung disease can be caused by pulmonary alveolar proteinosis, alveolar cell carcinoma, mineral oil pneumonia, sarcoidosis (alveolar form), lymphoma, tuberculosis, metastases, or desquamative interstitial pneumonia.

Death may occur rapidly with acute, massive pulmonary bleeding or over longer periods as the result of continued pulmonary failure and right heart failure. Historically, patients had an average survival of 2.5 years after diagnosis, but today 86% may survive beyond five years.

Restrictive lung diseases may be due to specific causes which can be intrinsic to the parenchyma of the lung, or extrinsic to it.

Genetic changes are very high in SCLC and LCNEC, but usually low for TC, intermediate for AC.

Neuroendocrine hyperplasia is a hyperplastic process that ultimately results in fibrosis of predominantly the pulmonary tree (the lungs). It is characterized by tachypnea, hypoxia, and retractions. There is no currently recognized treatment for the relentless progression of this disorder.

Acute interstitial pneumonitis occurs most frequently among people older than forty years old. It affects men and women equally. There are no known risk factors; in particular, smoking is not associated with increased risk.

Multifocal micronodular pneumocyte hyperplasia (MMPH) is a subtype of pneumocytic hyperplasia (hyperplasia of pneumocytes lining pulmonary alveoli).

Several synonymous terms have been done for this entity: adenomatoid proliferation of alveolar epithelium, papillary alveolar hamartoma, multifocal alveolar hyperplasia, multinodular pneumocyte hyperplasia.

These multifocal lesions are observed in tuberous sclerosis, and can be associated with lymphangioleiomyomatosis and perivascular epithelioid cell tumour (PEComa or clear cell "sugar tumor")).

It can be diagnosed through lung biopsy using thoracoscopy.