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{{SK}}Pulmonary mass


==Overview==  
==Overview==  
'''Lung mass''' (also known as "'''Pulmonary mass'''") is defined as any area of pulmonary opacification that measures more than 30 mm (3 cms) in the [[lung]]. Lung mass are abnormal growths found in the lung which can be either be [[benign]] or [[malignant]]. The most common cause of a pulmonary mass is lung cancer ('''in 95% of cases'''). Other less common causes of lung mass include [[granuloma]], [[lipoma]], [[tuberculosis]], and [[aspergillosis]].  Lung mass may be classified according to the location, imaging features, size, and distribution. The [[incidence]] rate of lung mass is approximately 58 per 100,000 individuals in the United States.<ref name="lung">National Lung Screening Trial. Wikipedia. https://en.wikipedia.org/wiki/National_Lung_Screening_Trial Accessed on February 4,2016</ref> The [[incidence]] of lung mass increases with age. Lung mass has a wide age distribution. However, the majority of these lesions are more often diagnosed in adults with the median age at diagnosis between 35 to 75 years. Males are more commonly affected than females with male to female ratio of 2:1. There is no racial predilection for lung mass.<ref name="pmid2244002">{{cite journal |vauthors=Littleton JT, Durizch ML, Moeller G, Herbert DE |title=Pulmonary masses: contrast enhancement |journal=Radiology |volume=177 |issue=3 |pages=861–71 |year=1990 |pmid=2244002 |doi=10.1148/radiology.177.3.2244002 |url=}}</ref> The most common symptom of a lung mass is [[cough]], which will gradually persist over time. Other symptoms may include [[dyspnea]], [[hemoptysis]], [[Coughing|chronic coughing]], [[wheezing]], and [[chest pain]]. In some cases, lung mass may be [[asymptomatic]]. A vital feature in the evaluation of lung mass includes [[malignancy]] assessment. The evaluation approach of lung mass starts with 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 [[therapeutic]] management, surveillance, and follow-up of the lung mass. As lung mass can be divided into two categories such as [[benign]] pulmonary mass and [[malignant]] pulmonary mass. Based upon these categories, complementary [[diagnostic]] studies and management include [[Positron emission tomography|PET/CT scan]], [[CT scan]], [[Biopsy|non-surgical biopsy]], and surgical resection.<ref name="pmid14736930">{{cite journal |vauthors=Spira A, Ettinger DS |title=Multidisciplinary management of lung cancer |journal=N. Engl. J. Med. |volume=350 |issue=4 |pages=379–92 |year=2004 |pmid=14736930 |doi=10.1056/NEJMra035536 |url=}}</ref>


'''Lung mass''' (also known as "'''Pulmonary mass'''") is generally defined as the growth of tissue in the [[lung]]. Abnormal growths found in the lung can be [[benign]] or [[malignant]]. A pulmonary mass is any area of pulmonary opacification that measures more than 30 mm. Lung masses may be classified according to location, imaging features, and size. In addition, lung masses may be sub-classified according if they are single or multiple. Lung masses are common, and they represent a wide range of pathologies in general population. The prevalence of lung masses is approximately 58 per 100,000 individuals. 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.
==Historical Perspective==
The first reported case of lung mass dates back to early 1400s when around 50% of miners in Germany and Czech Republic died of a pulmonary disease called Bergkrankheit.<ref name="pmid11606795">{{cite journal |author=Witschi H |title=A short history of lung cancer |journal=[[Toxicological Sciences : an Official Journal of the Society of Toxicology]] |volume=64 |issue=1 |pages=4–6 |year=2001 |month=November |pmid=11606795 |doi= |url=http://toxsci.oxfordjournals.org/cgi/pmidlookup?view=long&pmid=11606795 |accessdate=2011-12-09}}</ref> In 1929, German physician, Fritz Lickint published a paper suggesting that lung mass patients were likely to be smokers and launched an anti tobacco campaign in Germany. In 1950's, United States physician Cuyler Hammond and Ernest Wynder provided additional corroboration for a causal association between smoking and [[lung cancer]].


==Classification==  
==Classification==  
Lung mass may be classified on the basis of [[histopathology]] into [[benign]] lung mass and [[malignant]] lung mass. In addition, lung mass can be sub-classified according to the location, imaging features, size, and distribution.


Lung masses may be classified according to location, imaging features, and size. In addition, lung masses may be sub-classified according if they are single or multiple.
{{familytree/start |summary=Sample 1}}
{{familytree | | | | | | | | A01 |A01=Lung mass}}
{{familytree | | |,|-|-|-|-|-|+|-|-|-|-|-|.| | | }}
{{familytree | | C01 | | | | C02 | | | | C03 |C01=Location|C02=Histology|C03=Imaging Features}}
{{familytree | | |!| | | | | |!| | | | | |!| }}
{{familytree | | D01 | | | | D02 | | | | D03 |D01=•Pleural<br>•Endobronchial<br>•Parenchymal|D02=•Malignant mass<br>•Benign mass<br>|D03=•Hyperdense pulmonary mass<br>•Cavitating pulmonary mass}}
{{familytree/end}}
 
==Pathophysiology==
It is thought that lung mass is the result of [[genetic]] and environmental factors. [[Genetic mutation]] leads to uncontrolled [[cell proliferation]] which predispose to [[tumorigenesis]]. [[Genes]] involved in the [[pathogenesis]] of lung mass include mutations in K-ras [[oncogene]] and [[TP53]] [[tumor-suppressor gene]]. Other [[Gene|genes]] include [[mutation]] in  EML4-ALK, PIK3CA, c-[[C-MET|MET]], NKX2-1, LKB1 and [[BRAF (gene)|BRAF]] kinase. Environmental factors include [[smoking]] (most important [[carcinogen]]), [[radon]], [[asbestos]], [[viral infections]], and states of chronic [[lung]] inflammation, all of which may predispose to [[cellular]] damage and [[DNA mutations]] that may further lead to development of lung mass.


==Causes==
==Causes==
 
The most common cause of a pulmonary mass is [[lung cancer]] (in 95% of cases). Other less common causes include [[hamartomas]], [[Hodgkin's lymphoma]], pleural [[malignant mesothelioma]], [[metastasis]], [[granuloma]], [[lipoma]], [[tuberculosis]], and [[aspergillosis]].<ref name="pmid18400799">{{cite journal |vauthors=Gadkowski LB, Stout JE |title=Cavitary pulmonary disease |journal=Clin. Microbiol. Rev. |volume=21 |issue=2 |pages=305–33, table of contents |year=2008 |pmid=18400799 |pmc=2292573 |doi=10.1128/CMR.00060-07 |url=}}</ref>
Lung masses may be idiopathic or caused by [[precursor]] lesions. Precursor lesions for some lung masses, may include: infections, metaplasia, hamartomatous formation, or displasia.


==Differential Diagnosis==  
==Differential Diagnosis==  
Lung mass must be differentiated from other causes that cause [[cough]], [[chest pain]], or [[wheezing]] such as primary [[lung cancer]],  pulmonary [[abscess]], [[granulomas]], [[tuberculosis]], and [[metastases]].<ref name="pmid16829468">{{cite journal |vauthors=Bhatia K, Ellis S |title=Unusual lung tumours: an illustrated review of CT features suggestive of this diagnosis |journal=Cancer Imaging |volume=6 |issue= |pages=72–82 |year=2006 |pmid=16829468 |pmc=1693761 |doi=10.1102/1470-7330.2006.0013 |url=}}</ref>


Lung masses may be differentiated according to clinical features, laboratory findings, imaging features, histological features, and genetic studies, from other diseases that cause chronic or acute [[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]] of lung mass 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 with a male to female ratio of 2:1. There is no racial predilection for lung mass.<ref name="pmid2244002">{{cite journal |vauthors=Littleton JT, Durizch ML, Moeller G, Herbert DE |title=Pulmonary masses: contrast enhancement |journal=Radiology |volume=177 |issue=3 |pages=861–71 |year=1990 |pmid=2244002 |doi=10.1148/radiology.177.3.2244002 |url=}}</ref>


==Epidemiology and Demographics==  
==Risk Factors==
Bone and cartilage tumors are uncommon, they represent 0.2% of all neoplasms in general population. The prevalence of bone and cartilage tumors is approximately 0.9 per 100,000 individuals. [[Bone]] and [[cartilage]] tumors have a bimodal age distribution. These tumors are more frequent in children and adolescents, and older adults.  The average age at diagnosis is between 10-25 years old and 60-75 years old. Males are more commonly affected than females, with a 1.5:1 ratio.<ref name="pmid23087718">{{cite journal |vauthors=Franchi A |title=Epidemiology and classification of bone tumors |journal=Clin Cases Miner Bone Metab |volume=9 |issue=2 |pages=92–5 |year=2012 |pmid=23087718 |pmc=3476517 |doi= |url=}}</ref> Bone and cartilage tumors are slightly more common among individuals of Caucasian race.<ref name="pmid1954049">{{cite journal |vauthors=Tubiana-Hulin M |title=Incidence, prevalence and distribution of bone metastases |journal=Bone |volume=12 Suppl 1 |issue= |pages=S9–10 |year=1991 |pmid=1954049 |doi= |url=}}</ref>
The most potent risk factor in the development of lung mass is [[smoking]]. Other important risk factors include family history of [[lung cancer]] and high levels of [[air pollution]].


==Screening==
==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).<ref name=“lung screen">Lung Cancer: Screening http://www.uspreventiveservicestaskforce.org/Page/Document/UpdateSummaryFinal/lung-cancer-screening. Accessed on February 3, 2016 </ref><ref name=“JAMA”>Davis AM, Cifu AS. Lung Cancer Screening. JAMA. 2014;312(12):1248-1249. doi:10.1001/jama.2014.12272.</ref><ref name=“ludng">National Lung Screening Trial. Wikipedia. https://en.wikipedia.org/wiki/National_Lung_Screening_Trial Accessed on February 4,2016</ref>
According to the [[United states preventive services task force recommendations scheme|U.S. Preventive Services Task Force (USPSTF)]] there is sufficient evidence to recommend routine [[Screening (medicine)|screening]] for lung mass. [[Screening (medicine)|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).<ref name="lung">National Lung Screening Trial. Wikipedia. https://en.wikipedia.org/wiki/National_Lung_Screening_Trial Accessed on February 4,2016</ref><ref name="JAMA">Davis AM, Cifu AS. Lung Cancer Screening. JAMA. 2014;312(12):1248-1249. doi:10.1001/jama.2014.12272.</ref>


==Diagnosis==
==Diagnosis==
===Evaluation of Lung Mass===
A vital feature in the evaluation of lung mass includes [[malignancy]] assessment. The evaluation approach of lung mass depends upon the initial morphological findings of the mass such as size, margins, contours, and growth. Other characteristics such as location, clinical features, and distribution may be helpful in the [[therapeutic]] management, surveillance, and follow-up of the lung mass. Lung mass can be divided into two categories such as [[benign]] pulmonary mass and [[malignant]] pulmonary mass. Based upon these categories, complementary [[diagnostic]] studies and management include [[PET scan|PET]]/[[CT]] scan, non-surgical [[biopsy]], and surgical resection. [[CT scan]] is the initial method of choice for evaluation of lung mass. The following algorithm outlines the various steps involved in the assessment of a lung mass. <ref name="pmid2244002">{{cite journal |vauthors=Littleton JT, Durizch ML, Moeller G, Herbert DE |title=Pulmonary masses: contrast enhancement |journal=Radiology |volume=177 |issue=3 |pages=861–71 |year=1990 |pmid=2244002 |doi=10.1148/radiology.177.3.2244002 |url=}}</ref><ref name="pmid19835344">{{cite journal |vauthors=Albert RH, Russell JJ |title=Evaluation of the solitary pulmonary nodule |journal=Am Fam Physician |volume=80 |issue=8 |pages=827–31 |year=2009 |pmid=19835344 |doi= |url=}}</ref>
{{Familytree/start}}
{{Familytree |boxstyle=background: #B0C4DE; color: #000000;  | | | | | | | A01 | | | | | | A01= <div style="float: left; text-align:center; width: 15em; padding:1em;">'''Chest X ray (CXR) shows opacity '''</div>}}
{{Familytree | | | |,|-|-|-|^|-|-|-|.| | | }}
{{Familytree |boxstyle=background: #B0C4DE; color: #000000; | | | B01 | | | | | | B02 | | | B01=<div style="float: left; text-align:center; width: 15em; padding:1em;">'''More than > 30 mm '''</div>
|B02=<div style="float: left; text-align:center; width: 15em; padding:1em;">  '''Less than <30 mm '''</div>}}
{{Familytree | | | |!| | | | | | | |!| | | | |}}
{{Familytree | | | |!| | | | | | | X02 | | | |X02=<div style="float: left; text-align:center; width: 15em; padding:1em;">'''[[Solitary pulmonary nodule|'''Pulmonary nodule''']]'''</div>}}
{{Familytree | | | |!| | | | | | | |!| | | |}}
{{Familytree | | | |!| | | | | |,|-|^|-|.| }}
{{Familytree | | | C01 | | | C03 | | |C04| |C01=<div style="float: left; text-align:center; width: 15em; padding:1em;">'''[[Lung mass]]''' <br> (also known as [[Pulmonary mass]]) <br> (Primary lung cancer <br>95% of the cases)</div>| C03=<div style="float: left; text-align:center; width: 15em; padding:1em;"> '''Multiple''' <br></div>
| C04=<div style="float: left; text-align:center; width: 15em; padding:1em;"> '''Single'''<br> (or '''solitary''') <br></div>}}
{{Familytree/end}}


===Evaluation of Bone or Cartilage Mass===


The evaluation of lung mass will depend on detailed [[medical history]], age, and morphology of the lesion.
For complete algorithm on evaluation of lung mass please [[Lung mass resident survival guide#FIRE: Focused Initial Rapid Evaluation|click here]]


===Staging===
===Staging===
According to the [[American Joint Committee on Cancer|American Joint Committee on Cancer (AJCC)]] staging system, there are 4 stages of malignant lung mass, based on 3 factors; [[tumor]] size, [[lymph node]] invasion, and [[metastasis]]. Each stage is assigned a letter and a number that designate T for [[tumor]] size, N for [[Lymph node|node]] invasion, and M for [[metastasis]].<ref name="canadian">Stages of non–small cell lung cancer. Canadian Cancer Society. http://www.cancer.ca/en/cancer-information/cancer-type/lung/staging/?region=ab</ref>


===History and Symptoms===
===History and Symptoms===
 
The most common symptom of a lung mass is [[cough]], which will gradually persist over time. Other common symptoms may include [[dyspnea]], [[hemoptysis]], [[Wheeze|wheezing]], and [[chest pain]]. Lung mass may also cause [[loss of appetite]], [[fatigue]] and [[cachexia]]. A positive history of [[smoking]], [[Asbestosis|exposure to asbestos]], [[tuberculosis infection]], or a [[Occupational safety and health|high risk occupation]] may be present in patients with lung mass. In addition, symptoms related with lung mass will vary depending upon the size and location of [[tumor]]. <ref name="pain">Non small cell lung cancer. Wikipedia. https://en.wikipedia.org/wiki/Non-small-cell_lung_carcinoma Accessed on February 24, 2016 </ref><ref name="pmid17505036">{{cite journal |vauthors=Raz DJ, Zell JA, Ou SH, Gandara DR, Anton-Culver H, Jablons DM |title=Natural history of stage I non-small cell lung cancer: implications for early detection |journal=Chest |volume=132 |issue=1 |pages=193–9 |year=2007 |pmid=17505036 |doi=10.1378/chest.06-3096 |url=}}</ref>
Lung masses are generally [[asymptomatic]]. The majority of patients may develop non-specific symptoms, such as: . 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, recent hospitalization, .<ref name="pmid26579486">{{cite journal |vauthors=Hakim DN, Pelly T, Kulendran M, Caris JA |title=Benign tumours of the bone: A review |journal=J Bone Oncol |volume=4 |issue=2 |pages=37–41 |year=2015 |pmid=26579486 |pmc=4620948 |doi=10.1016/j.jbo.2015.02.001 |url=}}</ref>


===Physical Examination===
===Physical Examination===
 
Physical examination findings of lung mass will depend on the location of the [[tumor]]. Lung mass with central location may cause [[Crackles|crackling sounds]], [[Wheezing|focal wheezing]], [[Hoarseness|voice hoarseness]], and [[tachypnea]]. Lung mass with peripheral location can present with [[pleurisy]] findings such as reduced [[chest expansion]]. Common physical examination of patients with lung mass, include crackling or bubbling noises, decreased/absent [[breath sounds]], and [[whispered pectoriloquy]].<ref name="pmid4813837">{{cite journal |vauthors=Hyde L, Hyde CI |title=Clinical manifestations of lung cancer |journal=Chest |volume=65 |issue=3 |pages=299–306 |year=1974 |pmid=4813837 |doi= |url=}}</ref>
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.<ref name="pmid4813837">{{cite journal |vauthors=Hyde L, Hyde CI |title=Clinical manifestations of lung cancer |journal=Chest |volume=65 |issue=3 |pages=299–306 |year=1974 |pmid=4813837 |doi= |url=}}</ref>
 


===Laboratory Studies===
===Laboratory Studies===
Laboratory findings associated with lung mass varies with underlying presentation. The findings may range from normal to severe elevated. In general, a thorough laboratory evaluation is necessary to accurately assess, diagnose and stage the severity of lung mass. Lab evaluations include [[complete blood count]], [[Electrolyte|electrolytes]], serum [[calcium]], [[alkaline phosphatase]], [[alanine aminotransferase]] (ALT), [[aspartate aminotransferase]] (AST), [[Bilirubin|total bilirubin]], serum [[creatinine]], [[albumin]], and [[lactate dehydrogenase]].<ref name="pmid14736930">{{cite journal |vauthors=Spira A, Ettinger DS |title=Multidisciplinary management of lung cancer |journal=N. Engl. J. Med. |volume=350 |issue=4 |pages=379–92 |year=2004 |pmid=14736930 |doi=10.1056/NEJMra035536 |url=}}</ref>


Laboratory findings consistent with the diagnosis of lung masses, may include:  elevated [[LDH]],  elevated [[alkaline phosphatase]] (related with prognosis), and elevated [[aspartate aminotransferase]] (AST).<ref name="pmid16815865">{{cite journal |vauthors=Tsukushi S, Katagiri H, Kataoka T, Nishida Y, Ishiguro N |title=Serum tumor markers in skeletal metastasis |journal=Jpn. J. Clin. Oncol. |volume=36 |issue=7 |pages=439–44 |year=2006 |pmid=16815865 |doi=10.1093/jjco/hyl046 |url=}}</ref>
===X ray===
 
An [[x-ray]] may be helpful in the [[diagnosis]] of lung mass. Findings on an x-ray suggestive of lung mass include rounded or spiculated mass, bulky hilum, and lobar collapse.
===Imaging===


Conventional radiography is initial method of choice for the diagnosis of long masses. The evaluation lung masses will depend on several characteristics, such as: size, pattern, presence of calcifications, attenuation, location, and previous imaging studies. CT is the gold standard for the complete evaluation of lung masses.  
===CT scan===
[[Computed tomography|CT scan]] is the method of choice for the evaluation of lung mass. On CT scan, characteristic findings of lung mass include single pulmonary nodule or mass with localized area of [[parenchymal]] [[Consolidation (medicine)|consolidation]] and bubble-like areas of low [[attenuation]] within the lung mass (characteristic finding).


===Biopsy===
===Biopsy===


Lung biopsy findings associated with lung masses will depend on tumor [[histology]], common findings include:
[[Biopsy]] for lung mass may be classified into two categories such as non-surgical [[biopsy]] and surgical [[biopsy]]. Biopsy findings associated with lung mass will depend on tumor [[histology]]. Common types of lung tissue biopsy for pulmonary mass include [[Bronchoscopy|conventional bronchoscopic-guided transbronchial biopsy]], bronchoscopic-transbronchial needle aspiration, endobronchial ultrasound-guided sheath transbronchial biopsy, and endobronchial ultrasound-guided transbronchial needle aspiration. Common indications for [[biopsy]] in lung mass include suspected [[lung cancer]] and to rule out [[malignant]] features ([[lymph node]] involvement).<ref name="pmid1746503">{{cite journal |vauthors=Herman M, Galanter M, Lifshutz H |title=Combined substance abuse and psychiatric disorders in homeless and domiciled patients |journal=Am J Drug Alcohol Abuse |volume=17 |issue=4 |pages=415–22 |year=1991 |pmid=1746503 |doi= |url=}}</ref><ref name="pmid15347106">{{cite journal |vauthors=Podbielski FJ, Rodriguez HE, Brown AM, Blecha MJ, Salazar MR, Connolly MM |title=Percutaneous biopsy in evaluation of lung nodules |journal=JSLS |volume=8 |issue=3 |pages=213–6 |year=2004 |pmid=15347106 |pmc=3016799 |doi= |url=}}</ref>
 
===Other Diagnostic Studies===


==Treatment==
===Medical Therapy===
Medical therapy of lung mass depends upon the [[histopathological]] analysis. In general, the therapy for lung mass consists of surgical [[excision]], [[radiation therapy]], [[chemotherapy]], and [[targeted therapy]].


===Surgery===
[[Surgery]] is the initial treatment choice for patients of lung mass with resectable [[tumors]]. Surgical excision is also the mainstay therapy for [[malignant]] lung mass. In lung mass, surgical procedure selection will depend on the size, margins, and invasion of the tumor. Common surgical procedures for the treatment of lung mass include [[Wedge resection (lung)|wedge resection]], segmentectomy, [[lobectomy]] and [[lung volume reduction surgery]].


===Primary Prevention===
Effective measures for the [[primary prevention]] of lung mass include [[smoking cessation]] and avoidance of second hand smoking. Lifestyle changes, such as healthy diet rich in fruits and vegetables and regular exercise may also reduce the risk of lung mass.


==References==
==References==
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{{reflist|2}}


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Latest revision as of 21:11, 23 March 2018



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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] Akshun Kalia M.B.B.S.[3]

Synonyms and keywords:Pulmonary mass

Overview

Lung mass (also known as "Pulmonary mass") is defined as any area of pulmonary opacification that measures more than 30 mm (3 cms) in the lung. Lung mass are abnormal growths found in the lung which can be either be benign or malignant. The most common cause of a pulmonary mass is lung cancer (in 95% of cases). Other less common causes of lung mass include granuloma, lipoma, tuberculosis, and aspergillosis. Lung mass may be classified according to the location, imaging features, size, and distribution. The incidence rate of lung mass is approximately 58 per 100,000 individuals in the United States.[1] The incidence of lung mass increases with age. Lung mass has a wide age distribution. However, the majority of these lesions are more often diagnosed in adults with the median age at diagnosis between 35 to 75 years. Males are more commonly affected than females with male to female ratio of 2:1. There is no racial predilection for lung mass.[2] 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 mass may be asymptomatic. A vital feature in the evaluation of lung mass includes malignancy assessment. The evaluation approach of lung mass starts with 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 therapeutic management, surveillance, and follow-up of the lung mass. As lung mass can be divided into two categories such as benign pulmonary mass and malignant pulmonary mass. Based upon these categories, complementary diagnostic studies and management include PET/CT scan, CT scan, non-surgical biopsy, and surgical resection.[3]

Historical Perspective

The first reported case of lung mass dates back to early 1400s when around 50% of miners in Germany and Czech Republic died of a pulmonary disease called Bergkrankheit.[4] In 1929, German physician, Fritz Lickint published a paper suggesting that lung mass patients were likely to be smokers and launched an anti tobacco campaign in Germany. In 1950's, United States physician Cuyler Hammond and Ernest Wynder provided additional corroboration for a causal association between smoking and lung cancer.

Classification

Lung mass may be classified on the basis of histopathology into benign lung mass and malignant lung mass. In addition, lung mass can be sub-classified according to the location, imaging features, size, and distribution.

 
 
 
 
 
 
 
Lung mass
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Location
 
 
 
Histology
 
 
 
Imaging Features
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
•Pleural
•Endobronchial
•Parenchymal
 
 
 
•Malignant mass
•Benign mass
 
 
 
•Hyperdense pulmonary mass
•Cavitating pulmonary mass

Pathophysiology

It is thought that lung mass is the result of genetic and environmental factors. Genetic mutation leads to uncontrolled cell proliferation which predispose to tumorigenesis. Genes involved in the pathogenesis of lung mass include mutations in K-ras oncogene and TP53 tumor-suppressor gene. Other genes include mutation in EML4-ALK, PIK3CA, c-MET, NKX2-1, LKB1 and BRAF kinase. Environmental factors include smoking (most important carcinogen), radon, asbestos, viral infections, and states of chronic lung inflammation, all of which may predispose to cellular damage and DNA mutations that may further lead to development of lung mass.

Causes

The most common cause of a pulmonary mass is lung cancer (in 95% of cases). Other less common causes include hamartomas, Hodgkin's lymphoma, pleural malignant mesothelioma, metastasis, granuloma, lipoma, tuberculosis, and aspergillosis.[5]

Differential Diagnosis

Lung mass must be differentiated from other causes that cause cough, chest pain, or wheezing such as primary lung cancer, pulmonary abscess, granulomas, tuberculosis, and metastases.[6]

Epidemiology and Demographics

The incidence of lung mass 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 with a male to female ratio of 2:1. There is no racial predilection for lung mass.[2]

Risk Factors

The most potent risk factor in the development of lung mass is smoking. Other important risk factors include family history of lung cancer and high levels of air pollution.

Screening

According to the U.S. Preventive Services Task Force (USPSTF) there is sufficient evidence to recommend routine screening for lung mass. 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][7]

Diagnosis

Evaluation of Lung Mass

A vital feature in the evaluation of lung mass includes malignancy assessment. The evaluation approach of lung mass depends upon the initial morphological findings of the mass such as size, margins, contours, and growth. Other characteristics such as location, clinical features, and distribution may be helpful in the therapeutic management, surveillance, and follow-up of the lung mass. Lung mass can be divided into two categories such as benign pulmonary mass and malignant pulmonary mass. Based upon these categories, complementary diagnostic studies and management include PET/CT scan, non-surgical biopsy, and surgical resection. CT scan is the initial method of choice for evaluation of lung mass. The following algorithm outlines the various steps involved in the assessment of a lung mass. [2][8]

 
 
 
 
 
 
Chest X ray (CXR) shows opacity
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
More than > 30 mm
 
 
 
 
 
Less than <30 mm
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Lung mass
(also known as Pulmonary mass)
(Primary lung cancer
95% of the cases)
 
 
Multiple
 
 
Single
(or solitary)
 


For complete algorithm on evaluation of lung mass please click here

Staging

According to the American Joint Committee on Cancer (AJCC) staging system, there are 4 stages of malignant lung mass, based on 3 factors; tumor size, lymph node invasion, and metastasis. Each stage is assigned a letter and a number that designate T for tumor size, N for node invasion, and M for metastasis.[9]

History and Symptoms

The most common symptom of a lung mass is cough, which will gradually persist over time. Other common symptoms may include dyspnea, hemoptysis, wheezing, and chest pain. Lung mass may also cause loss of appetite, fatigue and cachexia. A positive history of smoking, exposure to asbestos, tuberculosis infection, or a high risk occupation may be present in patients with lung mass. In addition, symptoms related with lung mass will vary depending upon the size and location of tumor. [10][11]

Physical Examination

Physical examination findings of lung mass will depend on the location of the tumor. Lung mass with central location may cause crackling sounds, focal wheezing, voice hoarseness, and tachypnea. Lung mass with peripheral location can present with pleurisy findings such as reduced chest expansion. Common physical examination of patients with lung mass, include crackling or bubbling noises, decreased/absent breath sounds, and whispered pectoriloquy.[12]

Laboratory Studies

Laboratory findings associated with lung mass varies with underlying presentation. The findings may range from normal to severe elevated. In general, a thorough laboratory evaluation is necessary to accurately assess, diagnose and stage the severity of lung mass. Lab evaluations include complete blood count, electrolytes, serum calcium, alkaline phosphatase, alanine aminotransferase (ALT), aspartate aminotransferase (AST), total bilirubin, serum creatinine, albumin, and lactate dehydrogenase.[3]

X ray

An x-ray may be helpful in the diagnosis of lung mass. Findings on an x-ray suggestive of lung mass include rounded or spiculated mass, bulky hilum, and lobar collapse.

CT scan

CT scan is the method of choice for the evaluation of lung mass. On CT scan, characteristic findings of lung mass include single pulmonary nodule or mass with localized area of parenchymal consolidation and bubble-like areas of low attenuation within the lung mass (characteristic finding).

Biopsy

Biopsy for lung mass may be classified into two categories such as non-surgical biopsy and surgical biopsy. Biopsy findings associated with lung mass will depend on tumor histology. Common types of lung tissue biopsy for pulmonary mass include conventional bronchoscopic-guided transbronchial biopsy, bronchoscopic-transbronchial needle aspiration, endobronchial ultrasound-guided sheath transbronchial biopsy, and endobronchial ultrasound-guided transbronchial needle aspiration. Common indications for biopsy in lung mass include suspected lung cancer and to rule out malignant features (lymph node involvement).[13][14]

Treatment

Medical Therapy

Medical therapy of lung mass depends upon the histopathological analysis. In general, the therapy for lung mass consists of surgical excision, radiation therapy, chemotherapy, and targeted therapy.

Surgery

Surgery is the initial treatment choice for patients of lung mass with resectable tumors. Surgical excision is also the mainstay therapy for malignant lung mass. In lung mass, surgical procedure selection will depend on the size, margins, and invasion of the tumor. Common surgical procedures for the treatment of lung mass include wedge resection, segmentectomy, lobectomy and lung volume reduction surgery.

Primary Prevention

Effective measures for the primary prevention of lung mass include smoking cessation and avoidance of second hand smoking. Lifestyle changes, such as healthy diet rich in fruits and vegetables and regular exercise may also reduce the risk of lung mass.

References

  1. 1.0 1.1 National Lung Screening Trial. Wikipedia. https://en.wikipedia.org/wiki/National_Lung_Screening_Trial Accessed on February 4,2016
  2. 2.0 2.1 2.2 Littleton JT, Durizch ML, Moeller G, Herbert DE (1990). "Pulmonary masses: contrast enhancement". Radiology. 177 (3): 861–71. doi:10.1148/radiology.177.3.2244002. PMID 2244002.
  3. 3.0 3.1 Spira A, Ettinger DS (2004). "Multidisciplinary management of lung cancer". N. Engl. J. Med. 350 (4): 379–92. doi:10.1056/NEJMra035536. PMID 14736930.
  4. Witschi H (2001). "A short history of lung cancer". Toxicological Sciences : an Official Journal of the Society of Toxicology. 64 (1): 4–6. PMID 11606795. Retrieved 2011-12-09. Unknown parameter |month= ignored (help)
  5. Gadkowski LB, Stout JE (2008). "Cavitary pulmonary disease". Clin. Microbiol. Rev. 21 (2): 305–33, table of contents. doi:10.1128/CMR.00060-07. PMC 2292573. PMID 18400799.
  6. Bhatia K, Ellis S (2006). "Unusual lung tumours: an illustrated review of CT features suggestive of this diagnosis". Cancer Imaging. 6: 72–82. doi:10.1102/1470-7330.2006.0013. PMC 1693761. PMID 16829468.
  7. Davis AM, Cifu AS. Lung Cancer Screening. JAMA. 2014;312(12):1248-1249. doi:10.1001/jama.2014.12272.
  8. Albert RH, Russell JJ (2009). "Evaluation of the solitary pulmonary nodule". Am Fam Physician. 80 (8): 827–31. PMID 19835344.
  9. Stages of non–small cell lung cancer. Canadian Cancer Society. http://www.cancer.ca/en/cancer-information/cancer-type/lung/staging/?region=ab
  10. Non small cell lung cancer. Wikipedia. https://en.wikipedia.org/wiki/Non-small-cell_lung_carcinoma Accessed on February 24, 2016
  11. Raz DJ, Zell JA, Ou SH, Gandara DR, Anton-Culver H, Jablons DM (2007). "Natural history of stage I non-small cell lung cancer: implications for early detection". Chest. 132 (1): 193–9. doi:10.1378/chest.06-3096. PMID 17505036.
  12. Hyde L, Hyde CI (1974). "Clinical manifestations of lung cancer". Chest. 65 (3): 299–306. PMID 4813837.
  13. Herman M, Galanter M, Lifshutz H (1991). "Combined substance abuse and psychiatric disorders in homeless and domiciled patients". Am J Drug Alcohol Abuse. 17 (4): 415–22. PMID 1746503.
  14. Podbielski FJ, Rodriguez HE, Brown AM, Blecha MJ, Salazar MR, Connolly MM (2004). "Percutaneous biopsy in evaluation of lung nodules". JSLS. 8 (3): 213–6. PMC 3016799. PMID 15347106.

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