A 64-year-old, Asian male presented to the Department of Respiratory Medicine at our hospital (a tertiary care hospital) on May 16, 2020 for cough and sputum with dyspnea for six months. Before the patient's visit, he had gradually aggravated dyspnea and presented chest tightness, chest pain, shortness of breath, edema of lower limbs and other symptoms, which had affected his daily life. However, he did not go to the local hospital for treatment. The patient reported a 5-year history of hypertension, up to 220/180mmHg, self-administered antihypertensive medication, and self-reported blood pressure control acceptable. He also had a 5-year history of previous cerebral infarction. No other history of disease has been reported. Physical examination showed a temperature of 36.4 C, apulse of 119 beats/min, a breath of 20 beats/min, and ablood pressure of 153/129mmHg. Sporadic wet rales can be heard in both lungs, no obvious abnormal heart sounds in the heart, and multiple enlarged lymph nodes can be touched in the neck, axilla and inguinal regions. The results of chest computed tomography (CT) (Day -2) with our hospital showed (Figure1 A1 and A2): right interlobar fissure, reticular nodular, diffuse thickening; right pleural effusion with partial package, scattered inflammation in the middle and lower lobes of the right lung with local external pressure atelectasis, scattered alveoli in both lungs; diffuse small nodular high density shadow in both lungs; plain strip shadow in the lower lingual segment of the upper lobe of the left lung. Laboratory examination results after admission: white blood cell 4.6 x 109/L, neutrophil% 88.0%, lymphocyte 0.19 x 109/L, eosinophils 0.00 x 109/L, procalcitonin 0.27ng/mL, N-terminal probrain natriuretic peptide (NT-proBNP) 295.00 pg/mL, D-dimer (D-D) 3.42 microg/mL, total protein (TP) 55.03 g/L, albumin (ALB) 27.81 g/L, no bacterial growth in blood culture (liquid culture), sputum culture (solid culture) for Streptococcus viridis (upper respiratory tract colonization bacteria). The detection of antibodies against Mycoplasma pneumoniae and Chlamydia pneumoniae showed that Chlamydia pneumoniae immunoglobulin G (IgG) 130.0 AU/mL, the rest of the antibodies were within the normal range, the respiratory pathogen spectrum antibody immunoglobulin M (IgM) test was negative, and the rest of the blood collection results were basically normal or abnormal results had no obvious clinical significance. Thoracic color Doppler ultrasound showed a 6.2cm dark fluid area in the right thoracic cavity, and cardiac ultrasound results showed aortic sclerosis, normal left ventricular systolic function measurements, and tachycardia. Based on the current findings, the patient was initially diagnosed with 1) right pneumonia, 2) right pleural effusion, 3) double pulmonary bullae, 4) hypertension. After initial diagnosis, the patient was given symptomatic and supportive treatment such as anti-infection, anti-inflammation, cough relief and phlegm elimination, blood pressure lowering and diuresis.
Refer to the diagnosis process of adult unilateral pleural effusion diagnosis guide, we consider further clarifying the etiology of pleural effusion in this patient, and performing puncture and drainage of right pleural effusion and submitting it for examination. The test results (Table 1) classify the nature of pleural effusion according to Light criteria, and finally determine the exudative pleural effusion. Thereafter, relevant examinations were further improved to clarify the cause of exudative pleural effusion in this patient. Among them, immune-related tests: the results of anti-nuclear antibody series (17items) were negative, the results of anti-neutrophil cytoplasmic antibody (ANCA) series were negative, the results of anti-cyclic citrullinated peptide (CCP) antibody were 19.43 RU/mL, the results of immunoglobulin + complement + rheumatism suggested that complement C3 0.73 g/L, C-reactive protein 186.34 mg/L, all kinds of immune serological indicators were basically normal, only the slight decrease of complement C3, while the significant increase of C-reactive protein was considered to be associated with pulmonary inflammation, so it was not considered as immune-related pleural effusion. Fungi-related detection: serum galactomannan test (galactomannan) < 0.25, 1.3-beta-D glucan test 53.14 pg/mL (reference result: < 70 pg/mL indicates a lower risk of infection, 70-90 pg/mL is recommended for continuous monitoring, and > 95 pg/mL is highly suspicious of infection), and pleural effusion related to fungal infection was not considered according to the test results. Thyroid function test: among the five items of thyroid function, only triiodothyronine T3 was slightly reduced by 0.95 nmol/L, and the rest had no abnormalities, so pleural effusion caused by thyroid function changes was not considered. However, the interferon-gamma release assay (T-SPOT) of tuberculosis infection was negative (-), and the multi-tumor markers were generally normal (among which the neuron-specific enolase was only slightly elevated, without reference significance). The two most common causes of pleural effusion are tuberculosis and tumors. Although current tests for tuberculosis and tumors were negative, the possibility of tumors or tuberculosis could not be ruled out. Therefore, further detection methods were needed to clarify the etiology of pleural effusion. 
Unfortunately, on the 8th day of admission, the patient's sudden dyspnea worsened, and NT-proBNP 2990 pg/mL and D-D 3.42 microg/mL were reexamined. The patient was transferred to intensify care unit (ICU) for treatment. After that, no venous thrombosis was found by venous ultrasound of lower limbs, no pulmonary embolism was found by computed tomography angiography (CTA) of the chest. Chest CT (Day 10) showed (Figure1 B1 and B2): decreased right pleural effusion, increased left pleural effusion, increased diffuse patchy and grid lesions of both lungs (considering the possibility of pulmonary edema combined with inflammation). Based on the above findings, we excluded the aggravation of acute dyspnea caused by pulmonary embolism. Considering that this aggravation may be due to acute heart failure and pulmonary edema induced by pulmonary infection, the symptomatic symptoms of dyspnea gradually improved after full anti-infection, recombinant human brain natriuretic peptide anti-heart failure, diuresis and other supportive treatment. However, the cause of the pleural effusion was still not clear at this time, and thus the additional left pleural effusion was sent for puncture and drainage (Table 1), and then the left and right pleural effusions were sent to NGS for testing respectively at this time.
A total of 39,575,303 reads were obtained from right pleural fluid samples, and 68 Mycobacterium tuberculosis complexes were detected (Figure 2A and B). A total of 38,603,770 reads were generated from left pleural fluid samples, and 1 read of Mycobacterium tuberculosis complex were detected (Figure 2C and D), covering 0.0010% (43/4,370,115) of the references genome. In order to validate the results of NGS detection, the detected specimens were also tested by real-time quantitative polymerase chain reaction (qPCR). The results of qPCR showed that Mycobacterium tuberculosis complex was positive in the right pleural fluid specimen, while no MTB was detected in the left pleural fluid specimen.
MTB was detected in both NGS specimens, and MTB infection was confirmed in qPCR of right pleural effusion specimen, so the patient was diagnosed as tuberculous pleurisy. At this time, after full anti-infection, anti-inflammation, cough relief, phlegm resolving, symptomatic support treatment, the patient's symptoms of cough, expectoration, dyspnea and other symptoms have been better than those at admission, and the condition was relatively stable. Chest CT (Day 15) reexamination showed (Figure1 C1 and C2): absorption of left pleural effusion, reduction of right pleural effusion, improvement of bilateral pulmonary inflammation. According to the relevant national laws and regulations, tuberculosis is an infectious disease, and patients should receive designated treatment in infectious disease hospitals. In order to standardize anti-tuberculosis treatment and to prevent recurrence of the disease, the patient was discharged from the hospital and transferred to the tuberculosis infectious disease hospital for systematic treatment.
The patient's condition improved after standard anti-tuberculosis treatment in Tuberculosis Infectious Disease Hospital, and the anti-tuberculosis treatment was effective, which confirmed the diagnosis of tuberculous pleurisy again. At this time, the patient was generally in good condition, and we contacted the patient to ask him to return for CT scan efficacy evaluation, but he just rejected the request and has not returned so far.