Empyema differential diagnosis

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Empyema Microchapters

Patient Information

Overview

Classification

Subdural empyema
Pleural empyema

Differential Diagnosis

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Prince Tano Djan, BSc, MBChB [2]

Overview

Empyema must be diffrentiated from pneumonia, lung abscess, lung cancer and parapneumonic effusions on the basis of the presentation, physical examination findings, chest xray, ultrasound and CT scan findings. For instance on ultrasound, empyema is positive for suspended microbubble sign, air fluid level, curtains sign and loss of gliding sign but these are negative in a lung abscess.

Again empyema is differentiated from a lung abscess in that empyema on CT scan is seen as a lung mass whose cavity is regular with smooth well-defined boundary and shape changes with change in patient's position.[1] Mass may resolve on antibiotics. The split pleura sign is present[2] (most reliable sign to differentiate empyema from lung abscess).[3]

Differential diagnosis

Empyema must be diffrentiated from pneumonia, lung abscess, lung cancer and parapneumonic effusions as shown below:

Variable Empyema Thoracis Lung abscess Pleural effusion Pneumonia Lung cancer
Presentation Variable presentation

but may follow long standing pneumonia

Usually has history of aspiration pneumonia, alcoholics, drug abusers, seizure disorder, have undergone recent general anesthesia, or have a nasogastric or endotracheal tube. Usually follows pneumonia as a complication presents with fever, pleuritc chest pain, cough mostly asymptomatic but may

have cough productive with

hemoptysis and

chronic history of smoking

Causes In general any bacteria

can cause an empyema, however different bacteria are associated

with different rates of empyema formation.[1]  Common causes include bacteroidesfusobacterium

haemophilus influenzaepneumococcal infections,

staphylococcus aureus,

streptococcusTB

Lung abscess is commonly caused by bacterial infections and these include bacteroides, peptostreptococcus and prevotella mostly after aspiration Common causes of transudative pleural effusion include;[1][2][3][4][5] left ventricular failureNephrotic syndrome, and cirrhosis, while common causes of exudative pleural effusions[6] are bacterial pneumonia and malignancy Pneumonia can result from a variety of causes, including infection with bacteriavirusesfungiparasites, and chemical injury to the lungs Direct cause of lung cancers

is DNA mutations that often

result in either activation

of proto-oncogenes

(e.g. K-RAS) or the inactivation of tumors suppressor genes

(e.g. TP53) or both. The risk of these genetic mutations may be increased following exposure to environmental components example smoking

Laboratory findings The pleural fluid typically has a low pH (<7.20),

low glucose (<60 mg/dL), and contains infectious organisms.

Therefore, the diagnosis relies on the presence of pus or organisms on gram stain. A positive bacteria culture from pleural fluid is not needed to make diagnosis of empyema.[4][5]

Raised inflammatory markers ( eg high ESRCRP) are usual but not specific The most widely used criteria is to differentiate between exudate and transudate using the light's criteria. Fluid is exudate when:
  • Pleural fluid protein/serum protein ratio >0.5
  • Fluid/serum lactic dehydrogenase (LDH) ratio >0.6
  • Fluid LDH greater than 2/3 the upper limits of normal of the serum LDH
Laboratory findings are non specific example leukocytosis, sputum samples for gram staining and culture. Other tests include urine antigen test, PCR, C-reactive protein and procalcitonin The laboratory findings are 

non specific including:

neutropeniahyponatremia,

hypokalemiahypercalcemia,

respiratory acidosis,

hypercarbiahypoxia, and

tumor cells in sputum and

pleural effusion cytology.

Physical examination On examination, the following

findings may be seen:[6][7][8]

Lateral chest wall swelling

and tenderness, clubbing of the fingernails, dull percussion note, r

educed breath sounds on the affected side of the chest, egophony, coarse crackles, increased tactile fremitus,

mediastinal shift to opposite side with large empyema

Chest examination shows features of consolidation such as localised dullness on percussion, bronchial breath sound etc.

Dental decay is common especially in alcoholics and children. Clubbing is present in one third of patients.

Bulging of the intercostal spaces,

decreased chest expansion

bronchovesicular breath sounds

of decreased intensity, egophony,

dullness to percussion,

decreased or absent fremitus.

Physical examination increased respiratory rate, low oxygen saturation, difficulty breathing, bronchial breathe sounds, increased tactile fremitus crackling sounds, or increased whispered pectoriloquy.  Physical examination findings are non specific and may include decreased/absent breath soundspallor, low-grade fever, tachypnea and cachezia.
CXR Chest X ray of empyema shows air-fluid level continuos homogenous pattern from the mediastinum to the chest wall forming obtuse angle with the lung parenchyma.[9]

Chest xray shows often unilateral cavity containing an air-fluid level and consolidation of lung parenchyema.

A homogenous opacification is noted at the affected side. The costophrenic angle is obliterated with a meniscus. CXR shows areas of diffused opacities. CXR may show lung mass, widening of the mediastinumatelectasis, or pleural effusion.
Chest ultrasound Ultrasound in empyema is positive

for suspended microbubble sign,

air fluid level, curtains sign

and loss of gliding sign.[10]

Ultrasound in lung abscess is negative for suspended microbubble sign, curtains sign and loss of gliding sign but air fluid level may be seen,.[11] Ultrasonography is helpful in making diagnosis of pleural effusion particularly in differentiating effusion from masses.[12] The extended thoracic spine sign on sonography has high sensitivity and specificity for diagnosing pleural effusion.[13] Chest or upper abdominal ultrasound may show subpulmonic effusion as shown below.[14][15][16] Not reqiured unless complicated with empyema USG is helpful in guiding biopsy, staging and estimating prognosis. It may show hypo- and hyperechogenic masses.[17][18][19]
CT scan Seen as a lung mass whose cavity

is regular with smooth

and regular lumen, well-defined

boundary and shape changes

with change in patient's position.[1]

Mass may resolve on antibiotics The split pleura sign is present[2]

(most reliable sign to differentiate

empyema from lung abscess)[3]

Lung mass whose cavity is rregular with undulated lumen, irregular-poorly defined boundary and shape does not change with change in patient's position.[20] Mass may resolve on antibiotics In most cases CT imaging may not provide additional information that would influence the clinical decision-making process.[21][22] [23] CT scan shows heterogeneous opacification of the affected side and cardiomediastinal shift to the opposite site in unilateral effusion.[24]
  • CT findings in pneumonia include:[1]
Seen as a spiculated irregular solid mass that does not resolve on antibiotics

References

  1. 1.0 1.1 Baber CE, Hedlund LW, Oddson TA, Putman CE (1980). "Differentiating empyemas and peripheral pulmonary abscesses: the value of computed tomography". Radiology. 135 (3): 755–8. doi:10.1148/radiology.135.3.7384467. PMID 7384467.
  2. 2.0 2.1 Stark DD, Federle MP, Goodman PC, Podrasky AE, Webb WR (1983). "Differentiating lung abscess and empyema: radiography and computed tomography". AJR Am J Roentgenol. 141 (1): 163–7. doi:10.2214/ajr.141.1.163. PMID 6602513.
  3. 3.0 3.1 Kraus GJ (2007). "The split pleura sign". Radiology. 243 (1): 297–8. doi:10.1148/radiol.2431041658. PMID 17392263.
  4. Mavroudis C, Ganzel BL, Cox SK, Polk HC (1987). "Experimental aerobic-anaerobic thoracic empyema in the guinea pig". Ann Thorac Surg. 43 (3): 298–302. PMID 3548615.
  5. Perez VP, Caierão J, Fischer GB, Dias CA, d'Azevedo PA (2016). "Pleural effusion with negative culture: a challenge for pneumococcal diagnosis in children". Diagn Microbiol Infect Dis. 86 (2): 200–4. doi:10.1016/j.diagmicrobio.2016.07.022. PMID 27527890.
  6. Atay S, Banki F, Floyd C (2016). "Empyema necessitans caused by actinomycosis: A case report". Int J Surg Case Rep. 23: 182–5. doi:10.1016/j.ijscr.2016.04.005. PMC 5022073. PMID 27180228.
  7. Gomes MM, Alves M, Correia JB, Santos L (2013). "Empyema necessitans: very late complication of pulmonary tuberculosis". BMJ Case Rep. 2013. doi:10.1136/bcr-2013-202072. PMC 3863066. PMID 24326441.
  8. Kuan YC, How SH, Yeen WC, Ng TH, Fauzi AR (2011). "Empyema thoracis complicated by pneumothorax necessitans manifesting as lobulated, localized subcutaneous emphysematous swellings". Ann Thorac Surg. 91 (6): 1969–71. doi:10.1016/j.athoracsur.2010.11.075. PMID 21619994.
  9. Moffett BK, Panchabhai TS, Nakamatsu R, Arnold FW, Peyrani P, Wiemken T; et al. (2016). "Comparing posteroanterior with lateral and anteroposterior chest radiography in the initial detection of parapneumonic effusions". Am J Emerg Med. 34 (12): 2402–2407. doi:10.1016/j.ajem.2016.09.021. PMID 27793503.
  10. Lin FC, Chou CW, Chang SC (2004). "Differentiating pyopneumothorax and peripheral lung abscess: chest ultrasonography". Am J Med Sci. 327 (6): 330–5. PMID 15201646.
  11. Lin FC, Chou CW, Chang SC (2004). "Differentiating pyopneumothorax and peripheral lung abscess: chest ultrasonography". Am J Med Sci. 327 (6): 330–5. PMID 15201646.
  12. Dickman E, Terentiev V, Likourezos A, Derman A, Haines L (2015). "Extension of the Thoracic Spine Sign: A New Sonographic Marker of Pleural Effusion". J Ultrasound Med. 34 (9): 1555–61. doi:10.7863/ultra.15.14.06013. PMID 26269297.
  13. Almeida FA, Eiger G (2008). "Subpulmonic effusion". Intern Med J. 38 (3): 216–7. doi:10.1111/j.1445-5994.2007.01619.x. PMID 18290818.
  14. Connell DG, Crothers G, Cooperberg PL (1982). "The subpulmonic pleural effusion: sonographic aspects". J Can Assoc Radiol. 33 (2): 101–3. PMID 7107669.
  15. Halvorsen RA, Thompson WM (1986). "Ascites or pleural effusion? CT and ultrasound differentiation". Crit Rev Diagn Imaging. 26 (3): 201–40. PMID 3536306.
  16. Mroz RM, Korniluk M, Swidzinska E, Dzieciol J, Czaban J, Panek B; et al. (2010). "Lung mass in a 28-year-old male: a case report of a rare tumor". Eur J Med Res. 15 Suppl 2: 95–7. PMC 4360372. PMID 21147631.
  17. Torun E, Fidan A, Cağlayan B, Salepçi T, Mayadağli A, Salepçi B (2008). "[Prognostic factors in small cell lung cancer]". Tuberk Toraks. 56 (1): 22–9. PMID 18330751.
  18. Filon E, Kodur E, Cygan M (1989). "[Ultrasonographic examination of the adrenal glands for detection of lung cancer metastasis]". Nowotwory. 39 (3–4): 157–61. PMID 2700089.
  19. Baber CE, Hedlund LW, Oddson TA, Putman CE (1980). "Differentiating empyemas and peripheral pulmonary abscesses: the value of computed tomography". Radiology. 135 (3): 755–8. doi:10.1148/radiology.135.3.7384467. PMID 7384467.
  20. Corcoran JP, Acton L, Ahmed A, Hallifax RJ, Psallidas I, Wrightson JM; et al. (2016). "Diagnostic value of radiological imaging pre- and post-drainage of pleural effusions". Respirology. 21 (2): 392–5. doi:10.1111/resp.12675. PMID 26545413.
  21. Federle MP, Mark AS, Guillaumin ES (1986). "CT of subpulmonic pleural effusions and atelectasis: criteria for differentiation from subphrenic fluid". AJR Am J Roentgenol. 146 (4): 685–9. doi:10.2214/ajr.146.4.685. PMID 3485341.
  22. Halvorsen RA, Thompson WM (1986). "Ascites or pleural effusion? CT and ultrasound differentiation". Crit Rev Diagn Imaging. 26 (3): 201–40. PMID 3536306.
  23. Wolverson MK, Crepps LF, Sundaram M, Heiberg E, Vas WG, Shields JB (1983). "Hyperdensity of recent hemorrhage at body computed tomography: incidence and morphologic variation". Radiology. 148 (3): 779–84. doi:10.1148/radiology.148.3.6878700. PMID 6878700.




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