Mediastinal Masses in Children: Radiologic-Pathologic Correlation

Pediatric mediastinal lymphatic malformation: misdiagnosis analysis and literature review

OBJECTIVES

Mediastinal cystic lymphatic malformation (MCLM) in children is prone to misdiagnosis as cystic teratoma. We compared the clinical and radiologic features between the two diseases and performed a cross-comparison with previous research on adult cases. This study aims to identify characteristic pediatric manifestations to improve diagnostic accuracy.

METHODS

A retrospective study of clinical and radiologic data was conducted on 12 MCLM and 20 cases of cystic teratomas confirmed by pathology or intervention biopsy. Clinical characters and radiology features (mass location and morphology, density, component, secondary complication) were recorded and compared. We reviewed clinical studies on MCLM published in the past decades, analyzing radiological differences and comparing pediatric MCLM cases at our hospital with those in the literature.

RESULTS

Group comparison in pediatrics between MCLM and cystic teratomas: There were significant age differences (p = 0.036), shape (p = 0.003), CT difference value (p < 0.001), CT difference ratio (p < 0.001), calcification (p < 0.001), fat (p < 0.001), and typing (p < 0.001) between the two diseases. An analysis of literature data on MCLM cases involved 16 studies.

CONCLUSION

The absence of internal fat or irregular morphology, along with a minimal CT difference value, may suggest the diagnosis of MCLM. In pediatric cases, anterior mediastinal diseases tend to extend toward the neck, and the presence of the thymus can complicate the component analysis, thereby increasing the risk of misdiagnosis. Clinical diagnosis and differential diagnosis of pediatric MCLM rely heavily on imaging evaluation.

Congenital Chest Lesions and Interventions

Anomalies of the fetal chest require advanced imaging with ultrasound and MR imaging as well as expertise on the part of the interpreting pediatric radiologist. Congenital diaphragmatic hernia and congenital lung malformation are the most frequently seen, and in both conditions, the radiologist should provide both detailed anatomic description and measurement data for prognostication. This article provides a detailed approach to imaging the anatomy, in-depth explanation of available measurements and prognostic value, and keys to identifying candidates for fetal intervention. Less common congenital lung tumors and mediastinal and chest wall masses are also reviewed.

Isolated Malignant Pleural Effusion in a Child: Unusual Presentation of Acute Leukemia

Pleural effusion in the pediatric population is an abnormal pathology characterized by the accumulation of fluids between the parietal and visceral pleura. The etiology of this excessive fluid accumulation can be attributed to both infectious and non-infectious factors. Notably, Streptococcus pneumoniae stands out as the predominant infectious agent responsible for this condition. Non-infectious causative factors encompass hematolymphoid malignancies, congestive heart failure, hemothorax, hypoalbuminemia, and iatrogenic causes. Among the hematolymphoid malignancies, lymphoma emerges as the most prevalent malignancy associated with pleural effusion. It is followed by T-cell lymphoblastic leukemia, germ cell tumor, neurogenic tumor, chest wall and pulmonary malignancy, carcinoid tumor, pleuro-pulmonary blastoma, and Askin's tumor, among others. Malignant pleural effusion is predominantly linked to T-cell lymphoblastic malignancies. In the context of acute lymphoblastic leukemia (ALL), cases where T-cell presentation is accompanied by leukemic pleural effusion are commonly associated with either a mediastinal mass or significant lymphadenopathy. Here, we describe a case of a four-year-old male child who exhibited a brief history of febrile illness. Notably, this case was characterized by isolated pleural effusion, devoid of any mediastinal mass or lymphadenopathy. Pathological investigations of pleural fluid analysis revealed the presence of malignant cells, facilitating an expedited diagnosis.

Imaging Features of Pediatric Sarcoidosis

Sarcoidosis is a granulomatous inflammatory disease of uncertain cause. It occurs most commonly in young and middle-aged adults and less frequently in children; therefore, few data on pediatric sarcoidosis exist in the literature. The diagnosis and management of sarcoidosis remain challenging because of diverse and often nonspecific clinical and imaging findings. In addition, the clinical picture varies widely by age. Prepubertal and adolescent patients often present with adult-like pulmonary disease; however, early-onset sarcoidosis is typically characterized by the triad of arthritis, uveitis, and skin rash. Sarcoidosis is mostly a diagnosis of exclusion made by demonstrating noncaseating granulomas at histopathologic examination in patients with compatible clinical and radiologic findings. Although sarcoidosis often affects the lungs and thoracic lymph nodes, it can involve almost any organ in the body. The most common radiologic manifestation is pulmonary involvement, characterized by mediastinal and bilateral symmetric hilar lymphadenopathies with perilymphatic micronodules. Abdominal involvement is also common in children and often manifests as hepatomegaly, splenomegaly, and abdominal lymph node enlargement. Although neurosarcoidosis and cardiac sarcoidosis are rare, imaging is essential to the diagnosis of central nervous system and cardiac involvement because of the risky biopsy procedure and its low diagnostic yield due to focal involvement. Being familiar with the spectrum of imaging findings of sarcoidosis may aid in appropriate diagnosis and management. ©RSNA, 2023 Test Your Knowledge questions are available in the supplemental material.

Cardiac and Pericardial Neoplasms in Children: Radiologic-Pathologic Correlation

Primary cardiac and pericardial neoplasms are rare in the pediatric population and can include both benign and malignant lesions. Rhabdomyomas, teratomas, fibromas, and hemangiomas are the most common benign tumors. The most common primary cardiac malignancies are soft-tissue sarcomas, including undifferentiated sarcomas, rhabdomyosarcomas, and fibrosarcomas. However, metastatic lesions are more common than primary cardiac neoplasms. Children with primary cardiac and pericardial tumors may present with nonspecific cardiovascular symptoms, and their clinical presentation may mimic that of more common nonneoplastic cardiac disease. The diagnosis of cardiac tumors has recently been facilitated using noninvasive cardiac imaging. Echocardiography is generally the first-line modality for evaluation. Cardiac MRI and CT are used for tissue characterization and evaluation of tumor size, extension, and physiologic effect. The varied imaging appearances of primary cardiac neoplasms can be explained by their underlying abnormality. Treatment of these lesions varies from conservative management, with spontaneous regression of some lesions such as rhabdomyomas, to surgical resection, particularly in patients with associated heart failure. With adequate imaging techniques and knowledge of the pathologic basis of the neoplasm, it is often possible to differentiate benign from malignant tumors, which can greatly affect adequate and timely treatment. ©RSNA, 2023 Quiz questions for this article are available through the Online Learning Center.

Clinical radiomics-based machine learning versus three-dimension convolutional neural network analysis for differentiation of thymic epithelial tumors from other prevascular mediastinal tumors on chest computed tomography scan

Purpose

To compare the diagnostic performance of radiomic analysis with machine learning (ML) model with a convolutional neural network (CNN) in differentiating thymic epithelial tumors (TETs) from other prevascular mediastinal tumors (PMTs).

Methods

A retrospective study was performed in patients with PMTs and undergoing surgical resection or biopsy in National Cheng Kung University Hospital, Tainan, Taiwan, E-Da Hospital, Kaohsiung, Taiwan, and Kaohsiung Veterans General Hospital, Kaohsiung, Taiwan between January 2010 and December 2019. Clinical data including age, sex, myasthenia gravis (MG) symptoms and pathologic diagnosis were collected. The datasets were divided into UECT (unenhanced computed tomography) and CECT (enhanced computed tomography) for analysis and modelling. Radiomics model and 3D CNN model were used to differentiate TETs from non-TET PMTs (including cyst, malignant germ cell tumor, lymphoma and teratoma). The macro F1-score and receiver operating characteristic (ROC) analysis were performed to evaluate the prediction models.

Result

In the UECT dataset, there were 297 patients with TETs and 79 patients with other PMTs. The performance of radiomic analysis with machine learning model using LightGBM with Extra Tree (macro F1-Score = 83.95%, ROC-AUC = 0.9117) had better performance than the 3D CNN model (macro F1-score = 75.54%, ROC-AUC = 0.9015). In the CECT dataset, there were 296 patients with TETs and 77 patients with other PMTs. The performance of radiomic analysis with machine learning model using LightGBM with Extra Tree (macro F1-Score = 85.65%, ROC-AUC = 0.9464) had better performance than the 3D CNN model (macro F1-score = 81.01%, ROC-AUC = 0.9275).

Conclusion

Our study revealed that the individualized prediction model integrating clinical information and radiomic features using machine learning demonstrated better predictive performance in the differentiation of TETs from other PMTs at chest CT scan than 3D CNN model.

Strategies for recognizing pneumonia look-alikes

Community-acquired pneumonia is a common diagnosis in children. Among the many children whose symptoms and/or chest X-ray is consistent with community-acquired pneumonia, it can be difficult to distinguish the rare cases of differential diagnoses that require specific management. The aim of this educational article is to provide clinicians with a series of questions to ask themselves in order to detect a possible differential diagnosis of pneumonia in children. The value of this approach is illustrated by 13 real clinical cases in which a child was misdiagnosed as having lobar pneumonia. What is Known: • When a lobar pneumonia is diagnosed, an appropriate antibiotic treatment leads to the resolution of the clinical signs in most cases. • However, several diseases can be look-alikes for pneumonia and mislead the practitioner. What is New: • This article provides a new approach to identify differential diagnoses of pneumonia in children. • It is illustrated by 13 real-life situations of children misdiagnosed as having pneumonia.

Pediatric mediastinal masses

Mediastinal masses are categorized based on the International Thymic Malignancy Interest Group (ITMIG) classification into prevascular, visceral and paravertebral compartments. The schema is based on cross-sectional imaging, mainly CT, and helps with generating a differential diagnosis based on location of the mass. Up to half of all pediatric mediastinal tumors are malignant. In this review we describe mediastinal masses that are relevant to the pediatric population, as well as the role of MR imaging of mediastinal masses and its advantages.

Pediatric sudden unexpected death due to undiagnosed mediastinal T-cell lymphoblastic lymphoma: A series of three cases

The literature on pediatric sudden unexpected death (SUD) due to unrecognized mediastinal neoplasms is limited to a small number of case reports with several cases confirmed to be secondary to T-cell lymphoblastic lymphoma (T-cell LBL). Mediastinal T-cell LBL can be rapidly progressive and potentially fatal due to the compression and obstruction of the airway and/or the great vessels. The clinical presentation is nonspecific with a predominance of respiratory symptoms that are more apparent when the patient is supine. We presented three cases of pediatric SUD attributed to forensic autopsy-diagnosed anterior mediastinal T- cell LBL. Case 1 involved a 2-year-old girl who presented with 9 days of cough and dyspnea. Postmortem examination revealed a firm rubbery mass surrounding the heart and compressing the bronchi. Case 2 involved a 3-year-old girl who suffered from a respiratory tract infection over several days. Autopsy revealed a firm nodular mass compressing the superior vena cava. Case 3 involved a 2-year-old boy who was found unresponsive, lying prone in his crib. He had cold-like symptoms for several days before his death. Postmortem examination revealed a firm, rubbery anterior mediastinal neoplasm surrounding the superior vena cava and great arteries. These three cases demonstrate the importance of identifying children with mediastinal masses that could potentially lead to life-threatening presentations and pediatric SUD. The forensic pathologist should consider a hematologic neoplasm at the time of autopsy in a previously healthy child who dies suddenly.