ABSTRACT
We present a case in which lung Ultrasound was relevant to reach an early diagnosis of lung tuberculosis and to manage the patient in the right setting. Moreover, ultrasound allowed to detect and treat massive pleural effusion through an ultrasound-guided thoracentesis.
Keywords: lung ultrasound, bedside, tuberculosis, pleural effusion.
INTRODUCTION
Tuberculosis (TB) is one of the leading causes of death due to infectious diseases, and it is a global health threat. TB incidence has undergone a rapid increase in the last decade, attributable to the increase in risk factors such as HIV co-infections, drug resistance and emigrations from areas where the disease is endemic. At today, TB is the major infectious causes of death in the world, with 1.6 million deaths in 20171. Here, we present the case of a young policeman referred to our hospital for dyspnoea and respiratory failure. Ultrasound utilization allowed to reach a fast and specific diagnostic program, and to perform a diagnostic thoracentesis. Subsequently, we performed a narrative review on the role of ultrasound in diagnosing lung tuberculosis.
CASE PRESENTATION
A 36-year-old Caucasian policeman was referred to our Emergency Department for dyspnoea. He reported persistent cough and fever with night sweats for about 2 weeks, for which antibiotic therapy with Levofloxacin 750 mg daily for 5 days was prescribed without clinical benefit. His past medical history was not suggestive for any disease.
Blood pressure (BP) and cardiac rhythm were normal (BP: 130/75 mmHg; heart rate: 91 bpm, sinus rhythm), but the arterial blood gas analysis revealed a respiratory failure (peripheral oxygen saturation: 87% on room air; pO2: 53 mmHg; pCO2: 41mmHg). The physical examination showed a hypo-expansion of the left hemithorax, reduced tactile fremitus, medium-basal hypophonesis with vesicular murmur abolished.
Blood laboratory tests showed a blood glucose level of 60 mg/dL (normal value 74-106), a C-reactive protein of 15.10 mg/dl (n.v. 0.00-0.50), and the following blood count: white blood cells 10.760/uL (n.v. 4.000-11.000), red blood cells 4.850.000/uL (n.v. 4.500.000-5.300.000), haemoglobin 14.2 g/dl (n.v. 13-16,0), neutrophils 7.810/uL (n.v. 2.100-7.100), lymphocytes 1.800/uL (n.v. 1.100-3.000), monocytes 1.080/uL (n.v. 200-960), eosinophils 50/uL (n.v. 0-500), basophils 20/uL (n.v. 0 -200).
Urea, creatinine, sodium, potassium, calcium, transaminases, gamma-glutamyl transpeptidase, amylase, lipase, lactate dehydrogenase, total and fractionated bilirubin, and procalcitonin were normal.
Chest X-ray was required, and we performed a bedside lung ultrasound (LUS) to complete physical examination.
LUS showed a massive finely corpuscular anechoic pleural effusion with thin branches of fibrin on the left, with a consolidated lung parenchyma collapsing to the hilum as for complete atelectasis; in the context of the consolidated lung parenchyma, multiple round hypo-anechoic formations were seen, with finely irregular margins, not assuming colordoppler signal: cavitations? Abscesses?(Fig.1-2).
Therefore, chest X-ray confirmed the pleural effusion associated with consensual parenchymal hypoventilation and showed a widespread non-specific thickening of the bronchial walls. No pleural effusion on the right and no signs of pneumothorax were appreciable. The cardiac shape was within limits. Surprisingly, the radiographic images did not show the anechoic roundish formations identified by US.
A therapy with oxygen supplementation was set and the patient was admitted to the infectious diseases ward and isolated according to US findings.
In the ward, an ultrasound-guided diagnostic-evacuative thoracentesis was performed with drainage of yellow citrine liquid. Moreover, chest computed tomography (CT) was performed to better characterize the images observed with US and not confirmed by chest X-ray, thus showing an excavated formation with fluid-air levels in the apical segment of the left lower lobe of about 6 x 3.5 cm (Fig.3). This formation was surrounded by an area of ​​slight increase in the density of the pulmonary parenchyma, with ground-glass appearance.
Another subpleural area of ​​parenchymal consolidation with pseudonodular morphology was present in the apicodorsal segment of the left upper lobe and appeared as excavated and communicating with the adjacent bronchus. A parenchymal consolidation area with appreciable subpleural morphology was present in the apical segment of the right upper lobe, showing a maximum axial diameter of about 2.2 cm and appeared excavated. Atelectasis striae in the lower segment of the lingula and in the basal pyramid of the left lower lobe were present. The findings described were therefore compatible with TB disease with cavitations. A fibrobronchoscopy was performed showing marked inflammation of the mucous membrane of the left bronchial hemisystem, where whitish secretions were detected.
The analysis of pleural fluid, bronchoalveolar lavage fluid and microbiological examination on sputum were positive for alcohol-acid resistant elements, confirming the diagnosis of pleuro-pulmonary TB. First-line specific antibiotic therapy was therefore set up and the patient was discharged on the seventh day in good clinical condition with indication for outpatient follow-up. The final diagnosis was pleuro-pulmonary cavitary tubercolosis.
DISCUSSION & LITERATURE REVIEW
In past years, LUS has shown an increasing utilization in the diagnostic field alongside traditional diagnostic tests. Although the presence of an air interface below the pleura prevents the visualization of the lung in depth, the evaluation of sonographic artifacts allows to evaluate several pathological conditions and it is a useful tool to address a more focused and quickly diagnosis.
To our knowledge, there are few data about US findings in lung TB2 focusing on the following fields of interest: detection of pleural effusion, assessment of residual pleural thickening, the execution of trans-thoracic needle biopsy, assessment of mediastinal lymphadenopathies and detection of pulmonary involvement in miliary TB3.
Sonographic pattern of pulmonary TB can be visualized as consolidations, subpleural nodules, pleural thickenings, fibrosis, pleural effusion and pneumothorax together with miliary pattern2,4,5. The miliary pattern has been described by Hunter et al6 as characterized by bilateral vertical artifacts (B-lines and/or “comet-tail artifacts”) in multiple lung areas, and by sub-pleural granular changes, that may be more characteristic of miliary TB6. However, these findings are not so specific, since similar bilateral vertical artifacts have been described in patients with Pneumocystis jirovecii or cytomegaly virus pneumonia and sub-pleural US alterations can be found in other pulmonary conditions such as metastatic thyroid cancer6.
Agostinis et al2 classified the sonographic findings in patients with lung TB into two categories: lung (subpleural nodule, pleural effusion, miliary pattern and cavitations) and extra-lung (pericardial effusion, splenomegaly, abdomen lymph nodes, hepatomegaly, ascites) US findings2. The hypoecoic subpleural nodules (SUNs) were the most frequently identified in sixty adults with diagnosis of lung TB in a rural African setting2. Consolidations were detected in about half of the patients and are indistinguishable from bacterial pneumonia, while cavitations were identified in three patients and described as anechoic or hypoechoic areas within solid lung consolidation2. SUNs were not identified in subjects without TB, suggesting a probable important role in lung TB diagnosis2.
The accuracy of LUS in the diagnosis of pulmonary TB in adults have been investigated in a recent study4. Montuori et al4 demonstrated that the combination of apical consolidations and SUNs found in the same patients has a specificity of 96% and a sensibility of 31%, while when at least one of these signs is identified, the sensitivity and the specificity are respectively of 86 and 63%4. Moreover, according to Agostinis et al2, cavitations were found to be the least common sign and not enough sensitive also in this study, probably due to the presence of air in cavitations or to the fact that a high number of lesions do not reach the pleura4.
In our case, the identification of the non-vascularized hypo-anechoic roundish lesions compatible with cavitations, in relation to the clinical context, was fundamental in the diagnostic suspicion of cavitary TB and for the early isolation of our patient in order to avoid the spreading of the infection in the crowded environment of the Emergency Room. It must be considered that our patient had not apparent risk factors for TB (patient medical history and lifestyle, HIV-negative test), and that the chest X-ray did not show the cavitations identified by US, so that the patient would have been hospitalized in a medical setting without the necessary isolation measures. Even if chest CT and microbiological and laboratory tests were fundamental in the different diagnosis between cavitations and lung abscesses, the findings provided by bedside LUS were relevant to confirm our diagnostic suspicion, and therefore for the instauration of an effective therapy, as already described in critical care7. In our case, we did not identify SUNs and apical consolidations because the lung parenchyma was completely collapsed due to the massive pleural effusion. However, the chest CT performed after evacuation of pleural fluid documented parenchymal consolidations at the level of the apical segments of the left upper and lower lobes, and of the right upper lobe, typical lung fields where consolidations can be found in post-primary tuberculosis8.
LUS is increasingly employed to safely perform bedside thoracentesis7,9–11. In our case, the possibility of identifying the corpuscular nature of the pleural fluid has contributed to the diagnostic suspicion5,12, and the US quantification of the fluid was fundamental to guide the therapeutic intervention13.
We did not perform a complete US evaluation of the abdomen since, in the Emergency setting and in the evaluation of the respiratory status of our patient who presented with a respiratory failure, we focused on the immediate evaluation of the lung parenchyma to diagnose the possible life-threatening conditions. However, the abdominal CT performed during hospitalization did not show lesions compatible with the dissemination of the disease.
Other possible applications of thoracic US in the diagnosis of TB are described in literature, especially in patients with suspected mediastinal TB (Table 1). Diagnosis of mediastinal TB is difficult due to non-specific clinical features and lack of characteristic radiographic features14. In order to obtain histopathological confirmation, a CT guided fine needle aspiration biopsy (FNAB) or invasive procedures such as mediastinoscopy or open surgical biopsy are often required14. US-guided FNAB has proven to be safe, and effective in the diagnosis of mediastinal TB14, despite its limitations for centrally located lesions due to the lack of a good acustic window15. More recently some authors have investigated the possibility of performing endobronchial ultrasound (EBUS)16,17, useful in investigating peripheral lung lesions, and also in guiding transbronchial FNAB and endoscopic aspiration from esophagus in suspected mediastinal TB18,19.
CONCLUSIONS
Bedside US is a safe, non-invasive, portable, versatile, easily repeatable and cost-effective imaging modality4,7. Its use can lead to the identification of specific pleuro-pulmonary pathological conditions by strengthening the clinical-diagnostic suspicion. Although nowadays there are few data about LUS evaluation in tuberculosis, in our case it was fundamental in the formulation of diagnostic suspect through direct visualization of the characteristic lung lesions and early isolation of the patient; early suspicion allowed to promptly request the specific diagnostic investigations and begin the targeted therapy. Our case has also confirmed that LUS is important for the identification, quantization and characterization of pleural effusion and for the execution of diagnostic and therapeutic ultrasound-guided thoracentesis.
Informed consent was obtained for patient data publication
Declaration of interests
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
No founding sources.