Cancer screening uses medical tests to detect disease in large groups of people who have no symptoms. For individuals with high risk of developing lung cancer, computed tomography (CT) screening can detect cancer and give a person options to respond to it in a way that prolongs life. This form of screening reduces the chance of death from lung cancer by an absolute amount of 0.3% (relative amount of 20%). High risk people are those age 55–74 who have smoked equivalent amount of a pack of cigarettes daily for 30 years including time within the past 15 years.

CT screening is associated with a high rate of falsely positive tests which may result in unneeded treatment. For each true positive scan there are about 19 falsely positives scans. Other concerns include radiation exposure and the cost of testing along with follow up. Research has not found two other available tests—sputum cytology or chest radiograph (CXR) screening tests—to have any benefit.

The United States Preventive Services Task Force (USPSTF) recommends yearly screening using low-dose computed tomography in those who have a total smoking history of 30 pack-years and are between 55 and 80 years old until a person has not been smoking for more than 15 years. Screening should not be done in those with other health problems that would make treatment of lung cancer if found not an option. The English National Health Service was in 2014 re-examining the evidence for screening.

Performing a chest radiograph is one of the first investigative steps if a person reports symptoms that may suggest lung cancer. This may reveal an obvious mass, widening of the mediastinum (suggestive of spread to lymph nodes there), atelectasis (collapse), consolidation (pneumonia) or pleural effusion. CT imaging is typically used to provide more information about the type and extent of disease. Bronchoscopy or CT-guided biopsy is often used to sample the tumor for histopathology.

Lung cancer often appears as a solitary pulmonary nodule on a chest radiograph. However, the differential diagnosis is wide. Many other diseases can also give this appearance, including metastatic cancer, hamartomas, and infectious granulomas such as tuberculosis, histoplasmosis and coccidioidomycosis. Lung cancer can also be an incidental finding, as a solitary pulmonary nodule on a chest radiograph or CT scan done for an unrelated reason. The definitive diagnosis of lung cancer is based on histological examination of the suspicious tissue in the context of the clinical and radiological features.

Clinical practice guidelines recommend frequencies for pulmonary nodule surveillance. CT imaging should not be used for longer or more frequently than indicated as extended surveillance exposes people to increased radiation.

Respiratory diseases may be investigated by performing one or more of the following tests

- Biopsy of the lung or pleura

- Blood test

- Bronchoscopy

- Chest x-ray

- Computed tomography scan, including high-resolution computed tomography

- Culture of microorganisms from secretions such as sputum

- Ultrasound scanning can be useful to detect fluid such as pleural effusion

- Pulmonary function test

- Ventilation—perfusion scan

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.

The definitive diagnosis is rendered by a microscopic examination, after excision. Typical carcinoids have cells with stippled chromatin and a moderate quantity of cytoplasm. They typically have few mitoses and lack necrosis. By definition, they are greater than 4 mm in largest dimension; smaller lesions are referred to as "pulmonary carcinoid tumourlets".

The differential diagnosis of typical pulmonary carcinoid tumour includes: "atypical pulmonary carcinoid tumour", "pulmonary carcinoid tumourlet" and "lung adenocarcinoma".

In most series, LCLC's comprise between 5% and 10% of all lung cancers.

According to the Nurses' Health Study, the risk of large cell lung carcinoma increases with a previous history of tobacco smoking, with a previous smoking duration of 30 to 40 years giving a relative risk of approximately 2.3 compared to never-smokers, and a duration of more than 40 years giving a relative risk of approximately 3.6.

Another study concluded that cigarette smoking is the predominant cause of large cell lung cancer. It estimated that the odds ratio associated with smoking two or more packs/day for current smokers is 37.0 in men and 72.9 in women.

Multiple abnormal laboratory findings have been noted in indium lung. High levels of serum indium have been found in all cases of indium lung. Other abnormal laboratory values that have been found include elevated alanine aminotransferase, elevated aspartate aminotransferase, elevated C-reactive protein, elevated interstitial lung disease markers, and elevated GM-CSF autoantibodies.

LCC is, in effect, a "diagnosis of exclusion", in that the tumor cells lack light microscopic characteristics that would classify the neoplasm as a small-cell carcinoma, squamous-cell carcinoma, adenocarcinoma, or other more specific histologic type of lung cancer.

LCC is differentiated from small-cell lung carcinoma (SCLC) primarily by the larger size of the anaplastic cells, a higher cytoplasmic-to-nuclear size ratio, and a lack of "salt-and-pepper" chromatin.

Lung carcinoids typically present with a cough or hemoptysis. Findings may closely mimic malignant tumours of the lung, i.e. lung cancer.

The exact cause of rheumatoid lung disease is unknown. However, associated factors could be due largely to smoking. Sometimes, the medicines used to treat rheumatoid arthritis, especially methotrexate, may result in lung disease.

Prevention's:

- Stop smoking: Chemicals found in cigarettes can irritate already delicate lung tissue, leading to further complications.

- Having regular checkups: The doctor could listen to lungs and monitor breathing, because lung problems that are detected early can be easier to treat.

Chest x-rays of affected individuals typically reveal nonspecific alveolar opacities. Diagnosis is generally made by surgical or endoscopic biopsy of the lung, revealing the distinctive pathologic finding. The current gold standard of PAP diagnosis involves histopathological examination of alveolar specimens obtained from bronchoalveolar lavage and transbronchial lung biopsy.

Microscopically, the distal air spaces are filled with a granular, eosinophilic material that is positive with the PAS stain and the PAS diastase stain. The main histomorphologic differential diagnosis is pulmonary edema, which does not have dense bodies.

An ELISA to measure antibodies against GM-CSF has been validated for routine clinical diagnosis of autoimmune PAP.

Lung cancers have been historically classified using two major paradigms. Histological classification systems group lung cancers according to the appearance of the cells and surrounding tissues when they are viewed under a microscope. Clinical classification systems divide lung cancers into groups based on medical criteria, particularly their response to different treatment regimens.

Before the mid-1900s, lung cancer was considered to be a single disease entity, with all forms treated similarly. In the 1960s, small cell lung carcinoma (SCLC) was recognized as a unique form of lung cancer, based both on its appearance (histology) and its clinical properties, including much greater susceptibility to chemotherapy and radiation, more rapid growth rate, and its propensity to metastasize widely early on in its course. Since then, most oncologists have based patient treatment decisions on a dichotomous division of lung cancers into SCLC and non-small cell lung carcinomas (NSCLC), with the former being treated primarily with chemoradiation, and the latter with surgery.

An explosion of new knowledge, accumulated mainly over the last 20 years, has proved that lung cancers should be considered an extremely heterogeneous family of neoplasms with widely varying genetic, biological, and clinical characteristics, particularly their responsiveness to the large number of newer treatment protocols. Well over 50 different histological variants are now recognized under the 2004 revision of the World Health Organization ("WHO-2004") typing system, currently the most widely used lung cancer classification scheme. Recent studies have shown beyond doubt that the old clinical classification paradigm of "SCLC vs. NSCLC" is now obsolete, and that correct "subclassification" of lung cancer cases is necessary to assure that lung cancer patients receive optimum management.

Approximately 98% of lung cancers are carcinoma, which are tumors composed of cells with epithelial characteristics. LCLC's are one of 8 major groups of lung carcinomas recognized in WHO-2004:

- Squamous cell carcinoma

- Small cell carcinoma

- Adenocarcinoma

- Large cell carcinoma

- Adenosquamous carcinoma

- Sarcomatoid carcinoma

- Carcinoid tumor

- Salivary gland-like carcinoma

CT scanning and radiography can be used to aid in the diagnosis of indium lung. CT abnormalities include ground-glass opacities, interlobular septal thickening, honeycombing, and bronchiectasis.

The diagnosis of RA was formerly based on detection of rheumatoid factor (RF). However, RF is also associated with other autoimmune diseases. The detection of anti-CCP is currently considered the most specific marker of RA. The diagnosis of rheumatoid lung disease is based on evaluation of pulmonary function, radiology, serology and lung biopsy. High resolution CT scans are preferred to chest X-rays due to their sensitivity and specificity.

Associated doctors to diagnosis this properly would be a Rheumatologists or Pulmonologist.

Within a physical examination doctors could find possible indications, such as hearing crackles (rales) when listening to the lungs with a stethoscope. Or, there may be decreased breath sounds, wheezing, a rubbing sound, or normal breath sounds. When listening to the heart, there may be abnormal heart sounds. Bronchoscopic, video-assisted, or open lung biopsy allows the histological characterization of pulmonary lesions, which can distinguish rheumatoid lung disease from other interstitial lung diseases.

The following tests may also show signs of rheumatoid lung disease:

- Chest x-ray may show:

- pleural effusion

- lower zone predominant reticular or reticulonodular pattern

- volume loss in advanced disease

- skeletal changes, e.g. erosion of clavicles, glenohumeral erosive arthropathy, superior rib notching

- Chest CT or HRCT features include:

- pleural thickening or effusion

- interstitial fibrosis

- bronchiectasis

- bronchiolitis obliterans

- large rheumatoid nodules

- single or multiple

- tend to be based peripherally

- may cavitate (necrobiotic lung nodules)

- cavitation of a peripheral nodule can lead to pneumothorax or haemopneumothorax.

- follicular bronchiolitis

- small centrilobular nodules or tree-in-bud

- rare

- Caplan syndrome

- Echocardiogram (may show pulmonary hypertension)

- Lung biopsy (bronchoscopic, video-assisted, or open), which may show pulmonary lesions

- Lung function tests

- Needle inserted into the fluid around the lung (thoracentesis)

- Blood tests for rheumatoid arthritis

The U.S. Preventive Services Task Force (USPSTF) issues recommendations for various cancers:

- Strongly recommends cervical cancer screening in women who are sexually active and have a cervix at least until the age of 65.

- Recommend that Americans be screened for colorectal cancer via fecal occult blood testing, sigmoidoscopy, or colonoscopy starting at age 50 until age 75.

- Evidence is insufficient to recommend for or against screening for skin cancer, oral cancer, lung cancer, or prostate cancer in men under 75.

- Routine screening is not recommended for bladder cancer, testicular cancer, ovarian cancer, pancreatic cancer, or prostate cancer.

- Recommends mammography for breast cancer screening every two years from ages 50–74, but does not recommend either breast self-examination or clinical breast examination. A 2013 Cochrane review concluded that breast cancer screening by mammography had no effect in reducing mortality because of overdiagnosis and overtreatment.

Unlike diagnostic efforts prompted by symptoms and medical signs, cancer screening involves efforts to detect cancer after it has formed, but before any noticeable symptoms appear. This may involve physical examination, blood or urine tests or medical imaging.

Cancer screening is not available for many types of cancers. Even when tests are available, they may not be recommended for everyone. "Universal screening" or "mass screening" involves screening everyone. "Selective screening" identifies people who are at higher risk, such as people with a family history. Several factors are considered to determine whether the benefits of screening outweigh the risks and the costs of screening. These factors include:

- Possible harms from the screening test: for example, X-ray images involve exposure to potentially harmful ionizing radiation

- The likelihood of the test correctly identifying cancer

- The likelihood that cancer is present: Screening is not normally useful for rare cancers.

- Possible harms from follow-up procedures

- Whether suitable treatment is available

- Whether early detection improves treatment outcomes

- Whether the cancer will ever need treatment

- Whether the test is acceptable to the people: If a screening test is too burdensome (for example, extremely painful), then people will refuse to participate.

- Cost

Adenosquamous lung carcinoma (AdSqLC) is a biphasic malignant tumor arising from lung tissue that is composed of at least 10% by volume each of squamous cell carcinoma (SqCC) and adenocarcinoma (AdC) cells.

"Lung tumors" are neoplastic tumors of the lung These include:

Primary tumors of the lung/pulmonary system:

- Bronchial leiomyoma, a rare, benign tumor

- Lung cancer, the term commonly used to refer to "carcinoma of the lung"

- Pulmonary carcinoid tumor

- Pleuropulmonary blastoma

- Neuroendocrine tumors of the lung

- Lymphomas of the lung.

- Sarcomas of the lung.

- Some rare vascular tumors of the lung

Non-lung tumors which may grow into the lungs:

- Mediastinal tumors

- Pleural tumors

Metastasis or secondary tumors/neoplasms with other origin:

- Metastasis to the lung

A CT scan of the lungs and histopathology along with a history of working in the flocking industry can diagnose flock worker's lung. A differential diagnosis may also include Sjögren's syndrome and lymphoid interstitial pneumonia. Flock worker's lung may be misdiagnosed as asthma or recurrent pneumonia. Though X-rays may be abnormal, CT scans are more useful as a diagnostic tool in flock worker's lung. Other diagnostic methods may include a transbronchial biopsy or wedge biopsy.

The first advance in the treatment of pulmonary alveolar proteinosis came in November 1960, when Dr. Jose Ramirez-Rivera at the Veterans' Administration Hospital in Baltimore applied repeated "segmental flooding" as a means of physically removing the accumulated alveolar material.

The standard treatment for PAP is whole-lung lavage, in which the lung is filled with sterile fluid with subsequent removal of the fluid along with the abnormal surfactant material. This is generally effective at improving PAP symptoms, often for a prolonged period of time. Since the mouse discovery noted above, the use of GM-CSF injections has also been attempted, with variable success. Lung transplantation can be performed in refractory cases.

VALI is most common in patients receiving mechanical ventilation for acute lung injury or acute respiratory distress syndrome (ALI/ARDS).

Possible reasons for predisposition to VALI include:

- An injured lung may be at risk for further injury

- Cyclic atelectasis is particularly common in an injured lung

Large-cell carcinoma (LCC), like small-cell carcinoma (SCC) is very rare and only accounts for about 5% of all cervical cancers. Early-stage LCC are extremely aggressive and difficult to diagnose due to the sub-mucosal location of the tumor and intact overlying mucosa. As with SCC, in LCC early cases are asymptomatic. Later stages present with irregular bleeding, vaginal spotting, discharge, and pelvic pain. The basis for treatment of LCC tumors is derived from therapy used for SCC; when diagnosed, multimodal therapy should be considered just as with SCC.

Flock worker's lung can be prevented with engineering controls that protect workers from inhaling flock. Engineering controls to prevent inhalation of flock can include using guillotine cutters rather than rotary cutters, and ensuring that blades are sharp, since dull blades shear off more respirable particles. Flocking plants have also implemented medical surveillance programs for workers to diagnose cases at an earlier stage. Another technique for preventing flock worker's lung is cleaning the workplace with alternatives to compressed air in order to avoid resuspending particulates in the air.

Anal Pap smears similar to those used in cervical cancer screening have been studied for early detection of anal cancer in high-risk individuals. In 2011, the HIV clinic implemented a program to enhance access to anal cancer screening for HIV-positive men. Nurse practitioners perform anal Papanicolaou screening, and men with abnormal results receive further evaluation with high-resolution anoscopy. The program has helped identify many precancerous growths, allowing them to be safely removed.

Checking the cervix by the Papanicolaou test, or Pap test, for cervical cancer has been credited with dramatically reducing the number of cases of and mortality from cervical cancer in developed countries. Pap test screening every three to five years with appropriate follow-up can reduce cervical cancer incidence up to 80%. Abnormal results may suggest the presence of precancerous changes, allowing examination and possible preventive treatment. The treatment of low-grade lesions may adversely affect subsequent fertility and pregnancy. Personal invitations encouraging women to get screened are effective at increasing the likelihood they will do so. Educational materials also help increase the likelihood women will go for screening, but they are not as effective as invitations.

According to the 2010 European guidelines, the age at which to start screening ranges between 20 and 30 years of age, but preferentially not before age 25 or 30 years, and depends on burden of the disease in the population and the available resources.

In the United States, screening is recommended to begin at age 21, regardless of age at which a woman began having sex or other risk factors. Pap tests should be done every three years between the ages of 21 and 65. In women over the age of 65, screening may be discontinued if no abnormal screening results were seen within the previous 10 years and no history of CIN 2 or higher exists. HPV vaccination status does not change screening rates. Screening can occur every 5 years between ages 30 and 65 when a combination of cervical cytology screening and HPV testing is used and this is preferred. However, it is acceptable to screen this age group with a Pap test alone every three years. Screening is not beneficial before age 25 as the rate of disease is low. Screening is not beneficial in women older than 60 years if they have a history of negative results. The American Society of Clinical Oncology (ASCO) guideline has recommend for different levels of resource availability.

Liquid-based cytology is another potential screening method. Although it was probably intended to improve on the accuracy of the Pap test, its main advantage has been to reduce the number of inadequate smears from around 9% to around 1%. This reduces the need to recall women for a further smear. The United States Preventive Services Task Force supports screening every 5 years in those who are between 30 and 65 years when cytology is used in combination with HPV testing.

Pap tests have not been as effective in developing countries. This is in part because many of these countries have an impoverished health care infrastructure, too few trained and skilled professionals to obtain and interepret Pap tests, uninformed women who get lost to follow-up, and a lengthy turn-around time to get results. These realities have resulted in the investigation of cervical screening approaches that use fewer resources and offer rapid results such as visual inspection with acetic acid or HPV DNA testing.