Background
The clinical manifestations of cardiac masses are diverse and lack specificity, which makes it difficult for clinicians to detect and distinguish cardiac masses. Cardiac tumors are rare but can be associated with high morbidity and mortality [1]. In recent years, more and more noninvasive imaging methods have been used for cardiac lesions. Two-dimensional echocardiography is considered to be a guiding standard imaging examination for the evaluation of cardiac masses [2]. Contrast-enhanced perfusion echocardiography has advantages in distinguishing masses from benign and malignant tumors. We report a case of a cardiac mass that was suspected to be a malignant cardiac tumor before the operation and was finally diagnosed as cardiac tuberculoma by postoperative pathological examination.
Case Presentation
The 45-year-old male patient was admitted to our hospital reporting chest tightness, weight loss, and dyspnea for 3 months after exercise. The physical examination findings were normal on admission, and no precordial murmur was found in cardiac auscultation. The patient had lost 7.5 kg in the previous 6 months and reported not having a history of infections such as tuberculosis and hepatitis. The EKG was normal. No obvious abnormality was revealed by laboratory examinations. X-ray examination showed that the left lung had the appearance of ground glass, and the edge was clear. Transthoracic echocardiography (TTE) showed that there were a large number of pericardial effusions and a soft tissue mass measuring 7.7 cm × 4.5 cm in the upper mediastinum, which oppressed the right pulmonary artery and accelerated the blood flow of the left pulmonary artery (Figure 1A). The ejection fraction was 68%.
Two-Dimensional Transthoracic Echocardiography and Contrast-Enhanced Ultrasonography.
(A) Soft tissue visualized around the right pulmonary artery measuring 7.7 cm × 4.5 cm. (B) Degenerative inhomogeneous high enhancement in the mass and an oppressed right pulmonary artery.
To distinguish the mass clearly, contrast-enhanced ultrasonography (CEUS) was performed immediately. For the CEUS examination, the ultrasound system was switched to the contrast mode, with a mechanical index of 0.1–0.5. CEUS was performed with intravenous administration of 2.0 mL of SonoVue (Bracco, Milan, Italy). The contrast-specific imaging mode was adjusted to ensure the balance of ultrasound intensity, penetration, and duration of the contrast agent. The mass showed degenerative inhomogeneous high enhancement, and the boundary was unclear (Figure 1B). It was diagnosed as a malignant mediastinal tumor. Meanwhile, the patient underwent a contrast-enhanced chest CT scan. Punctate and patchy calcification could be seen in ill-defined lesions (Figure 2). Heterogeneous enhancement could be seen in the mass, and the lymph nodes around the aortic arch showed homogeneous enhancement. The CT results also suggested that it may be a malignant tumor.
To identify the cause and make a diagnosis, the patient underwent subxiphoid pericardial window drainage and thoracoscopic mediastinal mass biopsy. Mass tissue and lymph node tissue were taken for pathological examination. The results showed that there were nodules composed of multifocal epithelioid cells in the lymph nodes, and cellulose necrosis could be seen in some of the nodules, which was consistent with chronic granulomatous inflammation (Figure 3). In addition, the pericardial effusion specimen was negative for acid-fast staining. The pericardial effusion showed a large number of lymph cells, but no tumor cell infiltration.
Photomicrograph of the Tissue Biopsy Sample Showing a Langhans-Type Giant Cell (with nuclei arranged in a ring at the periphery) Surrounded by Epithelial Cells and Lymphocytes.
Treatment was started daily with an antituberculosis regimen of isoniazid (300 mg), rifampin (450 mg), pyrazinamide (750 mg), and ethambutol (750 mg) after the operation. The symptoms abated significantly, and the patient was discharged 3 weeks later. In a telephone follow-up, the patient reported that there was no longer chest tightness and dyspnea.
Discussion
The main manifestations in this case were large pericardial effusion and the upper mediastinum mass with heterogeneous enhancement on CEUS and CT. The initial diagnosis was considered to be a malignant tumor; thoracoscopic biopsy confirmed it was a granuloma.
Cardiac or mediastinal masses are still a challenging problem in TTE [3]. Two-dimensional echocardiography is still considered a first-line diagnostic method for evaluating cardiac masses, and it is reported that the sensitivity of TTE is 93% and the sensitivity of transesophageal echocardiography is 97% [2]. The difficulty of distinguishing thrombosis and benign and malignant tumors can be reduced by CEUS. The superiority of CEUS lies in observing the perfusion of mass by the degree and kind of enhancement, which can differentiate the neovascularization of malignancy from the avascularity of thrombus and the sparse vascularity of a benign tumor. CEUS can play an instrumental role in the confirmation of the diagnosis, the delineation of the anatomic extent of the mass, and the evaluation of involvement of other structures that may assist in defining the nature of the mass and the surgical decision. In addition, some researchers have found that dipyridamole stress quantitative real-time perfusion echocardiography is helpful for distinguishing between benign and malignant tumors [3], which may provide initial guidance for us to use new quantitative techniques such as parametric imaging in the future to better determine the characteristics of tumors [3].
Reviewing the whole case, taking into account the results of routine tests and the patient’s chief concern and the reported history of no tuberculosis, we did not consider the possibility of tuberculosis at first. CEUS showed a mass with degenerative heterogeneous enhancement and an unclear boundary that indicated a hypervascular and irregular projecting mass. We made the preliminary diagnosis of a malignant tumor. CT scan showed punctate and patchy calcification, an unclear boundary, and uneven enhancement, which increased the possibility of diagnosis of tuberculosis. Combined with these examinations, subxiphoid pericardial window drainage and thoracoscopic mediastinal mass biopsy were performed. The pathological findings indicated tuberculosis.
Tuberculoma, seen as well-defined nodules located mainly in the right upper lobes, may appear after primary tuberculosis or reactivation. Calcification occurs in about 20–30% of cases [4]. CT provides the best visualization of the calcifications and characteristics of the nodules, as well as the lymph gland. CT is also useful for showing the effect on the mediastinal cardiovascular structures and tracheobronchial trees. Tuberculous effusions are very rich in proteins and often show fibrin strands and septa on ultrasonography [4]. On CEUS examination, tuberculoma can show heterogeneous enhancement because of the pathological characteristic by which tuberculoma usually exhibits different stages of inflammatory exudation, caseous necrosis, and calcification simultaneously, and the lymph glands can show rim enhancement because of medullary necrosis. The radiological presentations of tuberculosis shows some variations, but each modality excels in providing different information. Radiology also plays a vital role in the treatment and follow-up of tuberculosis patients. When a localized mediastinal soft tissue is detected, multimodality imaging combined with the clinical history will increase the degree of diagnostic certainty.
The clinical presentation of tuberculosis has changed to having less classical presentation and increased incidence of extrapulmonary forms [5]. The differential diagnosis of masses of the anterior mediastinum and the middle mediastinum includes thymomas, lymphomas, thyroid masses, vascular masses, and lymph node enlargement due to metastases or granulomatous disease [6], Whereas the diagnosis of cardiac tuberculosis was almost exclusively made at autopsy previously, advances in imaging techniques provide an opportunity for earlier diagnosis. These advanced imaging techniques may contribute to an optimal morphological description, assessment of hemodynamic significance and surveillance using these advanced imaging techniques [6].
In addition to the imaging findings, the differential diagnosis of tuberculoma and tumor in this case can also focus on pericardial effusion. Ultrasound-guided pericardiocentesis is helpful for definite diagnosis. The pericardial fluid is bloodstained in 80% of cases of tuberculous pericarditis. In the study by Mayosi et al. [4], tuberculous pericarditis presented clinically in three forms: namely, pericardial effusion, constrictive pericarditis, and a combination of effusion and constriction.
Conclusion
Although this case was initially not diagnosed by echocardiography and CT because of the variability of tuberculosis, TTE is still considered the first-line imaging modality for the assessment of cardiac masses. CEUS can confirm the presence of a cardiac or mediastinal mass and provide information on perfusion, which is used to complement TTE with improved detection of benign or malignant masses. Multimodality imaging plays a pivotal role in the evaluation of cardiac masses.