Lung mass overview
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Maria Fernanda Villarreal, M.D. [2]
Overview
Lung mass (also known as "Pulmonary mass") is generally defined as any area of pulmonary opacification that measures more than 30 mm in the lung. Abnormal growths found in the lung can be benign or malignant. Lung masses may be classified according to location, imaging features, size, and distribution. The most common cause of a pulmonary mass is lung cancer. Other causes, include: granuloma, dystrophic calcifications, tuberculosis, and fungus ball. The incidence rate of lung masses is approximately 58 per 100 000 individuals in the United States. The incidence of lung masses increases with age; the median age at diagnosis is between 35 to 75 years. Males are more commonly affected with lung masses than females. The male to female ratio is approximately 2 to 1. There is no racial predilection for lung masses. Lung masses have a wide age distribution. However, the majority of these lesions are more often diagnosed in adults. The most common symptom of a lung mass is cough, which will gradually persist over time. Other symptoms may include: dyspnea, hemoptysis, chronic coughing, wheezing, and chest pain. In some cases, lung masses may be asymptomatic. The evaluation of lung mass will depend on detailed medical history, morphology of the lesion, size, distribution.
Classification
Lung masses may be classified into 2 types: malignant or benign lung masses. In addition, lung masses can be sub-classified according to location, imaging features, size, and distribution.
Causes
The most common cause of a pulmonary mass is lung cancer. Other causes, include: granuloma, dystrophic calcifications, tuberculosis, and fungus ball.
Differential Diagnosis
Lung masses may be differentiated according to clinical features, laboratory findings, imaging features, histological features, and genetic studies, from other diseases that cause cough, chest pain, or wheezing. Common differential diagnosis includes: lung cancer, tuberculosis, pulmonary abscess, granulomas, loculated pleural effusion, and metastases.
Epidemiology and Demographics
The incidence rate of lung masses is approximately 58 per 100 000 individuals in the United States. The incidence of lung masses increases with age; the median age at diagnosis is between 35 to 75 years. Males are more commonly affected with lung masses than females. The male to female ratio is approximately 2 to 1. There is no racial predilection for lung masses.
Screening
According to the U.S. Preventive Services Task Force (USPSTF) there is sufficient evidence to recommend routine screening for lung masses. Screening for suspected lung cancer by low-dose computed tomography is recommended every year among smokers who are between 55 to 80 years old and who have history of smoke 30 pack-years or more and either continue to smoke or have quit within the past 15 years (grade B recommendation).[1][2][3]
Diagnosis
Evaluation of Lung Mass
A hallmark feature in the evaluation of lung mass is the malignancy assessment. The evaluation approach of lung mass will mainly depend in the initial morphological evaluation of the mass (size, margins, contours, and growth). Other characteristics, such as: location, clinical features, and distribution may be helpful for the therapeutical management, surveillance, and follow-up of lung mass. Lung mass can be divided into 2 categories: benign pulmonary mass and malignant lung mass. Based upon these categories, complementary diagnostic studies and management, include: PET/CT scan, CT scan, non-surgical biopsy, and surgical resection.
Imaging
Computed tomography is the method of choice for the evaluation of lung masses. The evaluation and risk assessment of lung mass will depend on several characteristics, such as: shape, calcification pattern, margins, location, distribution, and attenuation. Further evaluation of lung masses, should include other diagnostic studies, such as: bronchoscopy, sputum cytology, or mediastinoscopy. Other imaging study useful for the malignancy evaluation of lung masses is [PET]] scanning, which may be helpful for the detection of occult disease and malignancy assessment.[4]
Staging
According to the American Joint Committee on Cancer (AJCC) staging system, there are 4 stages of malignant lung masses, based on 3 factors: tumor size, lymph node invasion, and metastasis.[5] Each stage is assigned a letter and a number that designate T for tumor size, N for node invasion, and M for metastasis.
History and Symptoms
Lung masses are generally asymptomatic. The majority of patients may develop non-specific symptoms, such as: dyspnea, hemoptysis, chronic coughing, wheezing, and chest pain. Obtaining the detailed history is an important aspect of making a diagnosis of lung masses, specific areas of focus when obtaining the history, are personal history of cancer, family history of lung cancer, previous infections, or a recent hospitalization.[6]
Physical Examination
Physical examination findings of lung masses will depend on the location of the tumor. Common physical examination findings, include: reduced chest expansion, crackling or bubbling noises, decreased/absent breath sounds, and whispered pectoriloquy.[7]
Laboratory Studies
Laboratory findings consistent with the diagnosis of lung masses, may include: elevated LDH, elevated alkaline phosphatase (related with prognosis), and elevated aspartate aminotransferase (AST).[8]
References
- ↑ Lung Cancer: Screening http://www.uspreventiveservicestaskforce.org/Page/Document/UpdateSummaryFinal/lung-cancer-screening. Accessed on February 3, 2016
- ↑ Davis AM, Cifu AS. Lung Cancer Screening. JAMA. 2014;312(12):1248-1249. doi:10.1001/jama.2014.12272.
- ↑ National Lung Screening Trial. Wikipedia. https://en.wikipedia.org/wiki/National_Lung_Screening_Trial Accessed on February 4,2016
- ↑ Albert RH, Russell JJ (2009). "Evaluation of the solitary pulmonary nodule". Am Fam Physician. 80 (8): 827–31. PMID 19835344.
- ↑ Stages of non–small cell lung cancer. Canadian Cancer Society. http://www.cancer.ca/en/cancer-information/cancer-type/lung/staging/?region=ab
- ↑ Hakim DN, Pelly T, Kulendran M, Caris JA (2015). "Benign tumours of the bone: A review". J Bone Oncol. 4 (2): 37–41. doi:10.1016/j.jbo.2015.02.001. PMC 4620948. PMID 26579486.
- ↑ Hyde L, Hyde CI (1974). "Clinical manifestations of lung cancer". Chest. 65 (3): 299–306. PMID 4813837.
- ↑ Tsukushi S, Katagiri H, Kataoka T, Nishida Y, Ishiguro N (2006). "Serum tumor markers in skeletal metastasis". Jpn. J. Clin. Oncol. 36 (7): 439–44. doi:10.1093/jjco/hyl046. PMID 16815865.