Imaging Evaluation of Mediastinal Masses in Children and Adults: Practical Diagnostic Approach Based on A New Classification System

Positron emission tomography in the diagnosis and management of primary pediatric lung tumors

Primary pediatric lung tumors are uncommon and have many overlapping clinical and imaging features. In contrast to adult lung tumors, these rare pediatric neoplasms have a relatively broad histologic spectrum. Informed by a single-institution 13-year retrospective record review, we present an overview of the most common primary pediatric lung neoplasms, with a focus on the role of positron emission tomography (PET), specifically 18F-fluorodeoxyglucose (FDG) PET and 68Ga-DOTATATE PET, in the management of primary pediatric lung tumors. In addition to characteristic conventional radiographic and cross-sectional imaging findings, knowledge of patient age, underlying cancer predisposition syndromes, and PET imaging features may help narrow the differential. While metastases from other primary malignancies remain the most commonly encountered pediatric lung malignancy, the examples presented in this pictorial essay highlight many of the important conventional radiologic and PET imaging features of primary pediatric lung malignancies.

Mediastinal teratoma in children: A case series of misdiagnoses in a high-endemic tuberculosis setting

INTRODUCTION AND IMPORTANCE

Mediastinal teratoma is a rare extragonadal teratoma that frequently manifests with non-specific symptoms and is commonly misdiagnosed, particularly in Indonesia, where tuberculosis (TB) is endemic.

CASE PRESENTATION

Herein, we present two cases of children aged 19 months and 17 years old who were referred with chronic nonspecific symptoms of cough, tachypnea, chest pain, and hemoptysis. Both children were initially diagnosed with TB and both completed anti-tuberculosis treatment. After visiting several healthcare facilities, a mediastinal mass was finally diagnosed and they all underwent thoracotomy without any further complication. The histopathology findings revealed mature teratoma. All patients had satisfactory outcomes at follow-up visits.

CLINICAL DISCUSSIONS

Patients presented with non-specific symptoms are often clinically diagnosed with TB. However, primary healthcare doctors should consider other differential diagnoses when a child has non-specific respiratory symptoms, especially when chest X-ray findings are nonspecific and TB workup is negative.

CONCLUSIONS

The diagnosis of mediastinal masses is still challenging in Indonesia, as the diagnosis requires a vast array of work-up examinations, therefore, early recognition and referral are crucial for management.

Computer-aided diagnosis using embedded ensemble deep learning for multiclass drug-resistant tuberculosis classification

Introduction

This study aims to develop a web application, TB-DRD-CXR, for the categorization of tuberculosis (TB) patients into subgroups based on their level of drug resistance. The application utilizes an ensemble deep learning model that classifies TB strains into five subtypes: drug sensitive tuberculosis (DS-TB), drug resistant TB (DR-TB), multidrug-resistant TB (MDR-TB), pre-extensively drug-resistant TB (pre-XDR-TB), and extensively drug-resistant TB (XDR-TB).

Methods

The ensemble deep learning model employed in the TB-DRD-CXR web application incorporates novel fusion techniques, image segmentation, data augmentation, and various learning rate strategies. The performance of the proposed model is compared with state-of-the-art techniques and standard homogeneous CNN architectures documented in the literature.

Results

Computational results indicate that the suggested method outperforms existing methods reported in the literature, providing a 4.0%-33.9% increase in accuracy. Moreover, the proposed model demonstrates superior performance compared to standard CNN models, including DenseNet201, NASNetMobile, EfficientNetB7, EfficientNetV2B3, EfficientNetV2M, and ConvNeXtSmall, with accuracy improvements of 28.8%, 93.4%, 2.99%, 48.0%, 4.4%, and 7.6% respectively.

Conclusion

The TB-DRD-CXR web application was developed and tested with 33 medical staff. The computational results showed a high accuracy rate of 96.7%, time-based efficiency (ET) of 4.16 goals/minutes, and an overall relative efficiency (ORE) of 100%. The system usability scale (SUS) score of the proposed application is 96.7%, indicating user satisfaction and a likelihood of recommending the TB-DRD-CXR application to others based on previous literature.

Mediastinal lesions in children

The mediastinum is where thoracic lesions most frequently occur in young patients. The histological spectrum of diseases caused by the presence of several organs in the mediastinum is broad. Congenital lesions, infections, benign and malignant lesions, and vascular diseases are examples of lesions. Care should be taken to make the proper diagnosis at the time of diagnosis in order to initiate therapy promptly. Our task is currently made simpler by radiological imaging techniques.

Diagnostic approach for mediastinal masses with radiopathological correlation

PURPOSE

Mediastinal masses have various histopathological and radiological findings. Although lymphoma is the most common type of tumor, thymic epithelial and neurogenic tumors are common in adults and children, respectively, but several other types are difficult to distinguish. No previous review has simply and clearly shown how to differentiate mediastinal masses.

METHOD

We conducted a review of the latest mediastinal classifications and mass differentiation methods, with a focus on neoplastic lesions. Both older and recent studies were searched, and imaging and histopathological findings of mediastinal masses were reviewed. Original simple-to-use differentiation flowcharts are presented.

RESULTS

Assessing localizations and internal characteristics is very important for mediastinal mass differentiation. The mass location and affected organ/tissue should be accurately assessed first, followed by more qualitative diagnosis, and optimization of the treatment strategy. In 2014, the International Thymic Malignancy Interest Group presented a new mediastinal clinical classification. In this classification, mediastinal masses are categorized into three groups according to location: prevascular (anterior)-, visceral (middle)-, and paravertebral (posterior)-compartment masses. Then, the internal characteristics and functional images are evaluated.

CONCLUSIONS

Differentiation of mediastinal masses is very difficult. However, if typical imaging findings and clinical characteristics are combined, reasonable differentiation is possible. In each patient, proper differential diagnosis may contribute to better treatment selection.

Magnetic resonance imaging of the pediatric mediastinum: updates, tips and tricks

Magnetic resonance imaging (MRI) of the pediatric mediastinum is challenging for the practicing radiologist. Many confounding factors add to the complexity of pediatric mediastinal MRI including small patient size, broad spectrum of mediastinal pathologies, motion artifacts and the need for sedation in a significant portion of children. However, with special attention to motion-reduction techniques and knowledge of pediatric-specific considerations, pediatric radiologists can help to provide accurate and timely diagnosis and also prevent multimodality imaging where MRI might be all that is needed. The purpose of this paper was present a practical review of pediatric mediastinal MRI with particular emphasis on diseases where MRI is the primary imaging modality of choice. Additionally, the author addresses those mediastinal processes for which MRI serves as a secondary problem-solving imaging tool.

Acute Respiratory Failure With a Rare, Rapidly Progressing Pediatric Desmoid Tumor Anterior Mediastinal Mass

ABSTRACT

We present an unusual case of a 6-year-old boy who presented with the sudden presence of left neck mass and acute hypoxemic respiratory failure, whose subsequent imaging demonstrated a previously undiagnosed anterior mediastinal mass (AMM) extending into the left neck. Biopsy of the mass was consistent with a desmoid tumor, which is a rare cause of AMM in children. Desmoid tumors are locally aggressive, often invading and enveloping surrounding tissues, but overall slow growing. The sudden growth of the neck mass suggests a very aggressive desmoid tumor, causing an unexpected respiratory compromise. Anterior mediastinal masses may cause symptoms by compressing the heart, great vessels, and airways. However, the patient may adapt and develop compensatory mechanisms to counter the compressive effects. Emergency care of the patient with an AMM who presents with acute respiratory distress includes optimizing oxygenation through promoting a calm environment, oxygenating while minimizing positive end-expiratory pressure, maintaining the patient's compensatory mechanisms by minimizing sedation and muscle relaxation, positioning the patient to minimize compressive effects of the mass on the vital thorax structures, and early consultation with pediatric specialists to develop a shared-emergency treatment strategy and to secure an expedited disposition to the appropriate venue of care.

Extravascular MDCT Findings of Pulmonary Vein Stenosis in Children with Cardiac Septal Defect

Purpose: To retrospectively investigate the extravascular thoracic MDCT angiography findings of pulmonary vein stenosis (PVS) in children with a cardiac septal defect. Materials and Methods: Pediatric patients (age ≤ 18 years) with cardiac septal defect and PVS, confirmed by echocardiogram and/or conventional angiography, who underwent thoracic MDCT angiography studies from April 2009 to April 2021 were included. Two pediatric radiologists independently evaluated thoracic MDCT angiography studies for the presence of extravascular thoracic abnormalities in: (1) lung and airway (ground-glass opacity (GGO), consolidation, pulmonary nodule, mass, cyst, septal thickening, fibrosis, and bronchiectasis); (2) pleura (pleural thickening, pleural effusion, and pneumothorax); and (3) mediastinum (mass and lymphadenopathy). Interobserver agreement between the two independent pediatric radiology reviewers was evaluated with kappa statistics. Results: The final study group consisted of 20 thoracic MDCT angiography studies from 20 consecutive individual pediatric patients (13 males (65%) and 7 females (35%); mean age: 7.5 months; SD: 12.7; range: 2 days to 7 months) with cardiac septal defect and PVS. The characteristic extravascular thoracic MDCT angiography findings were GGO (18/20; 90%), septal thickening (9/20; 45%), pleural thickening (16/20; 80%), and ill-defined, mildly heterogeneously enhancing, non-calcified soft tissue mass (9/20; 45%) following the contours of PVS in the mediastinum. There was a high interobserver kappa agreement between two independent reviewers for detecting extravascular abnormalities on thoracic MDCT angiography studies (k = 0.99). Conclusion: PVS in children with a cardiac septal defect has a characteristic extravascular thoracic MDCT angiography finding. In the lungs and pleura, GGO, septal thickening, and pleural thickening are frequently seen in children with cardiac septal defect and PVS. In the mediastinum, a mildly heterogeneously enhancing, non-calcified soft tissue mass in the distribution of PVS in the mediastinum is seen in close to half of the pediatric patients with cardiac septal defect and PVS.

Mediastinal Masses in Children: Radiologic-Pathologic Correlation

Most pediatric masses in the chest are located in the mediastinum. These masses are often initially detected incidentally on chest radiographs in asymptomatic children, although some patients may present with respiratory symptoms. At chest radiography, the mediastinum has been anatomically divided into anterior, middle, and posterior compartments. However, with the International Thymic Malignancy Interest Group classification scheme, which is based on cross-sectional imaging findings, the mediastinum is divided into prevascular, visceral, and paravertebral compartments. In the prevascular compartment, tumors of thymic origin, lymphomas, germ cell tumors, and vascular tumors are encountered. In the visceral compartment, lymphadenopathy and masses related to the foregut are seen. In the paravertebral compartment, neurogenic tumors are most common. Using the anatomic location in combination with knowledge of the imaging and pathologic features of pediatric mediastinal masses aids in accurate diagnosis of these masses to guide treatment and management decisions. An invited commentary by Lee and Winant is available online. ^©RSNA, 2021.

ACR Appropriateness Criteria® Imaging of Mediastinal Masses

Mediastinal masses can present with symptoms, signs, and syndromes or incidentally. Selecting the appropriate diagnostic imaging study for mediastinal mass evaluation requires awareness of the strengths and weaknesses of the various imaging modalities with regard to tissue characterization, soft tissue contrast, and surveillance. This publication expounds on the differences between chest radiography, CT, PET/CT, ultrasound, and MRI in terms of their ability to decipher and surveil mediastinal masses. Making the optimal imaging choice can yield diagnostic specificity, avert unnecessary biopsy and surgery, guide the interventionist when necessary, and serve as a means of surveillance for probably benign, but indeterminate mediastinal masses. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Imaging findings of lesions in the middle and posterior mediastinum

Lesions in the middle and posterior mediastinum are relatively rare, but there are some useful radiological clues that can be used to diagnose them precisely. It is useful to determine the affected mediastinal compartment and the locations of the main thoracic nerves on medical images for diagnosing such mediastinal lesions. Neurogenic tumors can occur in the middle mediastinum, although they generally arise as posterior mediastinal tumors. Based on the above considerations, we review various characteristic imaging findings of middle and posterior mediastinal lesions, and their differential diagnoses.

The role of radiological imaging for masses in the prevascular mediastinum in clinical practice

Tumors in the prevascular compartment of the mediastinum are rare and imaging plays a major role in their detection, (differential) diagnosis, staging, and follow-up. The prevascular compartment is bordered anteriorly by the posterior aspect of the sternum, posteriorly by the ventral aspect of the pericardium, cranially by the thoracic outlet, and caudally by the diaphragm. In many cases, the diagnosis of a lesion in the prevascular compartment is an incidental finding either on chest radiograph (CR) or on computed tomography (CT) scans. The differential diagnosis of masses in the pre-vascular mediastinum include primarily tumors arising from the thymus or the thyroid gland, lymphomas and germ cell tumors. The differential diagnosis of mediastinal masses is primarily based on the location of the mass, its tissue composition (i.e., fat content, calcifications) and the age of the patient. The imaging method of choice is CT, as it combines a high spatial and temporal resolution with the ability to determine tissue composition and detect fluid components, as well as areas of fat and calcifications. MRI is used as a more specific problem-solving tool to discriminate solid lesions from cystic lesions or to provide evidence of minimal fat content in teratoma and thymic rebound. The role of PET/CT in the evaluation of tumors other than lymphomas in the prevascular compartment is still under discussion.

A 46-Year-Old Woman With a Mediastinal Mass

CASE PRESENTATION

A 46-year-old otherwise healthy woman visited the ED twice over a period of 4 days for chest discomfort, midback pain, and dyspnea. The pain was localized, constant, nonpleuritic in nature, moderate in severity, and was not relieved by over-the-counter medications.

Role of diffusion weighted MR-imaging in the evaluation of malignant mediastinal lesions

Background

Conducted studies showed that the ADC (apparent diffusion coefficient) values of malignant mediastinal lesions are significantly lower than those of benign lesions. Investigators determined cut-off ADC values to differentiate the two; concluding that ADC value is a promising noninvasive, imaging parameter that helps assess and characterize mediastinal tumors.

Taking this a step forward, the primary objective of our prospective study was to investigate the potential of DW-MRI (diffusion-weighted magnetic resonance imaging) to characterize malignant mediastinal lesions using their ADC values.

Thirty-three patients that underwent MRI of the chest with DWI and latter pathologically diagnosed with a malignant mediastinal lesion were included in this study. Lesions’ ADC values were measured and correlated with the histopathological results. The statistical significance of differences between measurements was tested using the one-way ANOVA (analysis of variance) test; p values equal to or less than 0.05 were considered significant.

Results

There was no statistically significant difference between the ADCmean values of the histopathological groups of lesions assessed with the overlap of their ADCmean values. The average ADCmean value of NHL (non-Hodgkin lymphoma) was evidently lower than that of HD (Hodgkin disease) with no overlap between their ADCmean values. DWI failed at characterizing one lesion in this study as a malignant tumor, namely an immature teratoma (germ-cell tumor). Again DWI could not be used to evaluate a mass, latter pathologically diagnosed as an angiosarcoma, because of its overall hemorrhagic nature showing no definite non-hemorrhagic soft tissue components. The aforementioned results did not differ considerably when minimum ADC was used instead of mean ADC.

Conclusion

There was no statistically significant difference between the ADC values of the malignant mediastinal lesions evaluated. However, regarding lymphoma subtypes, our limited sample study of lymphoma suggested a considerable difference between the ADC values of Hodgkin disease and non-Hodgkin lymphoma.

Clinical manifestation of pediatric mediastinal tumors, a single center experience

Medical decisions should be well-planned to improve prognosis and reduce complications of mediastinal tumors. In this study, we analyzed the clinical presentations of pediatric mediastinal tumors and their correlation with long-term clinical outcome.Forty patients under 18 years of age diagnosed with mediastinal tumors at China Medical University Children's Hospital between 2001 and 2016 were enrolled. The patients' sex, age of onset, initial clinical symptoms, and treatment outcomes were analyzed.75% of the patients with mediastinal tumors in this study were men, and the median age of onset was 13 years old (age range: 0-17 years). The overall mortality rate was 40%. The most common tumors were lymphoma (47.5%), followed by germ cell tumors (12.5%), neuroblastoma (12.5%), and thymoma (7.5%). Neuroblastoma was more prevalent in girls younger than 5 years old. The initial presentations of these patients included breathing difficulty (65%), productive cough (47.5%), pleural effusion (54.5%), superior vena cava (SVC) syndrome (35%), neck mass (35%), airway compression (32.5%), fever (30%), chest pain (27.5%), and pericardial effusion (25%). Lymphomas were more likely to be accompanied by neck mass (52.6% vs19.0%, P = .04) and SVC syndrome (52.6% vs 19.0%, P = .026), yet also had a better 1-year-survival rate (68.4% vs 52.4%, P = .02).Overall, lymphoma should be suspected when children present with neck mass and SVC syndrome. Neuroblastoma with a posterior mediastinal origin should be suspected among children younger than 5 years old. Tumor-related airway obstruction, pleural effusion, and pericardial effusion were leading cause of cardiopulmonary instability during sedation for invasive procedures, which should be managed cautiously.

Persistent radiologic thoracic hypotransparency: A case report and review of the literature

A thymolipoma is a slow-growing, anterior mediastinal tumor, rare in childhood. The authors present a report of a 4-year-old girl with persistent right thoracic hypotransparency on the chest radiograph. Computed tomography and magnetic resonance imaging revealed an anterior, well-limited, mediastinal mass of heterogeneous density, with lipomatous and soft tissue density areas. The tumor was totally excised and the histopathologic findings revealed a thymolipoma. A year and a half after surgery, the child remains well. This report enhances the relevance of differential diagnosis in the presence of persistent radiologic thoracic hypotransparency.

Combined transbronchoscopic needle aspiration (TBNA) and rapid on-site cytological evaluation (ROSE) for diagnosis of tuberculous mediastinal lymphadenitis: A case report

INTRODUCTION

The diagnosis of tuberculous mediastinal lymphadenitis remains a challenge, and the use of transbronchoscopic needle aspiration (TBNA) combined with rapid on-site cytological evaluation (ROSE) is still unclear. A case of tuberculous mediastinal lymphadenitis was illustrated to show the diagnostic value of TBNA and ROSE.

CASE PRESENTATION

In this case report, we presented a typical case of a 44-year-old male who underwent obvious odynophagia and mild symptom of dyspnea. One isolated mass positioned on posterior mediastinum was examined as positive discovery. Finally, he was diagnosed with tuberculous mediastinal lymphadenitis by using TBNA combined with ROSE and treated with anti-TB.

CONCLUSIONS

TBNA is an efficacious and safe approach, which is worth popularizing for the clinical diagnosis of mediastinal masses. Meanwhile, ROSE is useful to reduce the numbers of needle passes during TBNA. We aimed to emphasize 2 key points in this case report. Firstly, a rare symptom of Tuberculosis in adults was supported by the patient. Secondly, TBNA combined with ROSE is useful for the diagnosis of tuberculous mediastinal lymphadenitis.

The resident's point of view in the learning curve of thymic MIS: why should I learn it?

Minimally invasive surgery (MIS) in thoracic surgery became quite popular during the last years. The aim of introducing and performing more MIS is to reduce surgical trauma, pain and complications in patients. Training in MIS increases operative time and thus cost in theatre but thus improves with experience. For a resident, the cases should be well selected with experienced supervision in a suitable setting with supporting staff and optimal instruments. Understanding the anatomy of the lung, using simulators, and attending workshops makes the learning curve shorter.

Assessment of paraspinal neurogenic tumors with diffusion-weighted MR imaging

PURPOSE

To assess paraspinal neurogenic tumors with diffusion-weighted MR imaging.

METHODS

Retrospective analysis was done upon 34 patients with paraspinal neurogenic tumors that underwent diffusion-weighted MR imaging. The ADC values of the mediastinal neurogenic tumors were calculated and correlated with biopsy results.

RESULTS

The ADC of benign paraspinal neurogenic tumors (1.5 ± 0.28 × 10^-3 mm²/s) was significantly higher (P = 0.001) than that of malignant peripheral nerve sheath tumors (0.995 ± 0.198 × 10^-3 mm²/s). Selection of 1.15 × 10^-3 mm²/s as a cut-off point for differentiating malignant from benign neurogenic tumors revealed an area under the curve of 0.885, an accuracy of 91.1%, a sensitivity of 90.9%, and specificity of 91.3%. There was significant difference (P = 0.04) in the ADC of schwannomas (1.55 ± 0.29 × 10^-3 mm²/s) from neurofibromas (1.33 ± 0.08 × 10^-3 mm²/s). The cut-off ADC value of 1.44 × 10^-3 mm²/s was used to differentiate schwannomas and neurofibromas with an area under the curve of 0.86, an accuracy of 82.6%, a sensitivity of 100%, and a specificity of 76.5%.

CONCLUSION

Diffusion-weighted MR imaging is imaging parameter that can be used for differentiation of benign from malignant paraspinal neurogenic tumors.

Mid-Esophageal Diverticulum Mimicking an Aortic Aneurysm on Chest Radiography

BACKGROUND

Mid-esophageal region is an uncommon location of esophageal diverticula, a condition usually diagnosed in elderly individuals.

CASE REPORT

We report a case of an elderly male with incidental finding of mediastinal lesion, which was initially thought to be an aortic aneurysm. Further evaluation demonstrated a mid-esophageal diverticulum at the level of the carina. We present patient's medical history and imaging, followed by a discussion on symptoms and management.

CONCLUSIONS

Knowledge of benign conditions that might mimic a mediastinal vascular pathology is important for therapeutic and prognostic reasons, as they are often managed conservatively.

Diagnostic evaluation of mediastinal lesions: Analysis of 144 cases

Background:

Mediastinum is a “Pandora's box” with many neoplastic and nonneoplastic lesions. The purpose of this study was to analyze our institutional experience of mediastinal lesions on fine-needle aspiration cytology (FNAC) and/or biopsy.

Materials and Methods:

This study was an analysis of 144 patients who had undergone ultrasound-guided FNAC and/or core biopsy for mediastinal lesions.

Results:

A total of 144 cases of suspected mediastinal masses were seen, and in 139 cases, tissue diagnosis was attempted. Out of 139 cases, 93 cases were neoplastic in nature (67%), 32 were nonneoplastic (23%), and 14 remained inconclusive (10%). Among neoplastic mediastinal lesions, metastatic carcinoma (37.4%) was the most common neoplastic lesion, followed by non-Hodgkin's lymphoma (12.2%), Hodgkin's lymphoma (7.1%), thymic lesions (3.5%), etc. Among nonneoplastic conditions, tuberculosis was the most common lesion (20.1%). An accurate tissue diagnosis was made in 89.9% cases by FNAC or core biopsy of mediastinal lesions in this study. Procedure-related mortality was nil. Complications were mostly minor and included chest pain in 24.5%, small pneumothorax in 13.6% requiring closed tube thoracostomy in 1.4%, and scanty hemoptysis in 9.3% cases.

Conclusion:

Neoplastic mediastinal lesions are more common than nonneoplastic lesions, with metastatic carcinoma being the most common cause followed by tuberculosis. A wide variety of lesions observed in this study stress on the importance of cytohistological diagnosis in all cases of mediastinal lesions for the final diagnosis and management planning. A guided FNAC or core biopsy is still accurate, well tolerated, and devoid of major complications.