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Year : 2019  |  Volume : 36  |  Issue : 3  |  Page : 259-261  

Mouse in the pleural cavity

1 Department of Cardiology, SGPGIMS, Lucknow, Uttar Pradesh, India
2 Department of Radio Diagnosis, SGPGIMS, Lucknow, Uttar Pradesh, India

Date of Web Publication24-Apr-2019

Correspondence Address:
Dr. Neeraj Jain
Department of Radio Diagnosis, SGPGIMS, Lucknow, Uttar Pradesh
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/lungindia.lungindia_445_18

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How to cite this article:
Khanna R, Jain N, Goel PK, Kumar S. Mouse in the pleural cavity. Lung India 2019;36:259-61

How to cite this URL:
Khanna R, Jain N, Goel PK, Kumar S. Mouse in the pleural cavity. Lung India [serial online] 2019 [cited 2020 Oct 30];36:259-61. Available from: https://www.lungindia.com/text.asp?2019/36/3/259/256931


A 65-year-old male patient presented in the cardiology department with complaints of chest pain and breathlessness on exertion for 6 months. In view of angina-like symptoms, the patient underwent coronary angiography, which revealed triple-vessel disease. An additional radiopaque mobile round mass was noted overlapping the cardiac shadow, which was suspected to be located inside the cardiac chamber [Figure 1]. The radiopaque mass seemed to be located in the right ventricle (RV) and seen oscillating between RV cavity and RV outflow tract. Subsequently, echocardiography was done which did not reveal any intracardiac mass, and for further evaluation, contrast-enhanced computed tomography (CT) chest was performed on 64-slice multidetector CT scanner which did not reveal any intracardiac mass lesion; however, it showed the presence of focal dense calcification along the posterior pleura of lower lobes of both lung, which moves to the dependent position in the right decubitus CT scan, suggestive of wandering calcification in the pleural cavity [Figure 2]. Volume-rendered images of the chest showed well-circumscribed densities along posterior chest wall opposite eighth to ninth intercostal space [Figure 3]. In addition, it also showed triple-vessel coronary artery disease and bilateral pleural effusion.
Figure 1: Fluoroscopy in posterior–anterior view shows calcified mobile mass seemed to be in the right ventricle (a) and oscillating between right ventricular cavity and right ventricular outflow tract (b, c) (arrow)

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Figure 2: (a and b) Contrast-enhanced computed tomography sagittal sections show oval-shaped calcified density in bilateral pleural cavity, along posterior chest wall at opposite eighth-ninth intercostal space. Contrast-enhanced computed tomography right decubitus sections reveal calcified density moved to dependent position, along and left paravertebral region (c) and right lateral chest wall (d)

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Figure 3: Volume-rendered image of the chest shows well-circumscribed densities along posterior chest wall opposite eighth to ninth intercostal space

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Pleural mouse or thoracolithiasis is an uncommon, benign condition characterized by the formation of one or multiple calcified or noncalcified lesions within the pleural space; its reported incidence was found to be around 0.9% in a large study done by Kinoshita et al. in 2010.[1] However, their exact prevalence is not known because in majority of cases, they were mistaken as peripherally located calcified granuloma. It is also known by namaes of fibrin body, pleural stone, plurollith, and intrathoracic calculus. Only few case reports and case series are available in the literature.

The exact etiology behind their existence is not known, but prevalent theories suggest their origin from necrosis of mediastinal or pericardial fat; histologically they often consist of fibrous shell with fatty core. Calcification may or may not be present. Our case presented densely calcified loose bodies.[2]

These lesions are very rarely symptomatic, with majority of cases being detected incidentally on CT scan or other imaging modality. No age or sex predilection has been noted. Left pleural cavity is more frequently involved than right while the involvement of bilateral pleural cavity is very rare.[3]

Chest radiographs are not very useful due to their small size and nonspecific nature and can be erroneously diagnosed as calcified or noncalcified nodule. CT scan is the modality on which they are frequently detected and it is also used for the diagnosis. Thoracoliths appeared as oval or rounded well-circumscribed density with or without calcification in the pleural cavity or along the fissures. The calcification may be partial or complete, and other reported pattern includes diffuse, spotty, peripheral, or central.[1],[4]

Thoracoliths are frequently located in the peripheral part of the chest along the chest wall, diaphragm, or paraspinal region. They tend to move to the dependent position in sequential imaging; this mobile nature is pathognomonic of pleural mouse or thoracolithiasis. However, stationary position in sequential scans does not rule out its possibility, and hence, CT scan in decubitus position should be done whenever there is a suspicion of thoracoliths on routine imaging. They had displayed movement as early as 2-min interval between sequential scans. The size of stones varies from 5 to 15 mm.[1] The size remains stationary in majority of cases; however, increased size in sequential imaging has been described in few case reports.[5] In that case, differentiation from neoplasm may be difficult.

Our case showed bilateral well-circumscribed rounded and calcified densities in posterior peripheral part of the chest along the chest wall, which subsequently migrates to the dependent position in the right decubitus scan, i.e., the right one moves to the lateral chest wall, while left one in left paravertebral location.[2],[6]

MRI is usually not indicated; however, a single case report showed high-signal intensity of central core on both T1- and T2-weighted sequences.[7]

Differential diagnosis includes peripherally located calcified nodule, foreign body granuloma, or migration of gallstone in the pleural cavity following spillage of gallstone during laparoscopic cholecystectomy.[8],[9] No treatment or intervention is required due to its benign nature.

Pleural mouse of thoracolith is an uncommon benign condition, which does not require any treatment; however, awareness of this condition is very important as it can be confused with neoplastic lesion. The mobile nature of stones in pleural cavity is virtually diagnostic.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

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Conflicts of interest

There are no conflicts of interest.

   References Top

Kinoshita F, Saida Y, Okajima Y, Honda S, Sato T, Hayashibe A, et al. Thoracolithiasis: 11 cases with a calcified intrapleural loose body. J Thorac Imaging 2010;25:64-7.  Back to cited text no. 1
Kim Y, Shim SS, Chun EM, Won TH, Park S. A pleural loose body mimicking a pleural tumor: A case report. Korean J Radiol 2015;16:1163-5.  Back to cited text no. 2
Bhayana R, Chen YA, Deva DP. Bilateral mobile thoracolithiasis. J Radiol Case Rep 2014;8:16-20.  Back to cited text no. 3
Strzelczyk J, Holloway BJ, Pernicano PG, Kelly AM. Rolling stones in the pleural space: Thoracoliths on CT, and a review of the literature. Clin Radiol 2009;64:100-4.  Back to cited text no. 4
Suwatanapongched T, Nitiwarangkul C. Thin-section CT findings of thoracolithiasis. Jpn J Radiol 2017;35:350-7.  Back to cited text no. 5
Peungjesada S, Gupta P, Mottershaw AM. Thoracolithiasis: A case report. Clin Imaging 2012;36:228-30.  Back to cited text no. 6
Tanaka D, Niwatsukino H, Fujiyoshi F, Nakajo M. Thoracolithiasis – A mobile calcified nodule in the intrathoracic space: Radiographic, CT, and MRI findings. Radiat Med 2002;20:131-3.  Back to cited text no. 7
Oestmann JW, Bridenbaugh S, Eggeling I. Gallstone migration into the pleural space. Am J Gastroenterol 2000;95:836-7.  Back to cited text no. 8
Brazinsky SA, Colt HG. Thoracoscopic diagnosis of pleurolithiasis after laparoscopic cholecystectomy. Chest 1993;104:1273-4.  Back to cited text no. 9


  [Figure 1], [Figure 2], [Figure 3]


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