Thymoma and thymic carcinoma in children and adolescents: A report from the European Cooperative Study Group for Pediatric Rare Tumors (EXPeRT)

Thymic carcinoma presenting with overlap polyarthritis and myositis: A rare paraneoplastic syndrome in childhood

Thymic tumors are very rare neoplasms in children and account for less than 1% of mediastinal tumors in pediatric patients. One-third of the pediatric patients present with symptoms related to the compression of the tumor mass on the surrounding anatomic structures, and paraneoplastic syndromes such as myasthenia gravis, pure red cell aplasia, acquired hypogammaglobulinemia, and connective tissue disorders, which rarely occur in children with thymic tumors. Herein, we report a case of thymic carcinoma mimicking the symptoms of a connective tissue disease with symmetrical polyarthritis accompanying myositis, fever, weight loss, and malaise in a 15-year-old male patient. To our knowledge, this is the first case pediatric thymic carcinoma accompany with severe polyarthritis and myopathy, thus we have reviewed the current literature regarding the cases of thymic malignancies coexisting with paraneoplastic syndromes in children.

Epidemiology of thymomas and thymic carcinomas in the United States and Germany, 1999-2019

Introduction

Mediastinal tumors, particularly non-neuroendocrine thymic epithelial tumors (TET) are relatively uncommon, posing challenges for extensive epidemiological studies. This study presents a comprehensive analysis of these tumors in the United States (US) and Germany (GER) from 1999 to 2019.

Methods

Patients aged 0-19 (n=478) and ≥20 years (n=17,459) diagnosed with malignant tumors of the anterior mediastinum were identified from the Surveillance, Epidemiology, and End Results registry (SEER) and the Zentrum für Krebsregisterdaten (ZfKD) databases.

Results

Among patients aged ≥20 years, TETs accounted for the most prevalent anterior mediastinal tumors (US/GER: 63%/64%), followed by lymphomas (14%/8%). For patients <20 years, predominant tumors included germ cell tumors (42%/14%), lymphomas (38%/53%), and TETs (10%/27%). The overall annual incidence of thymoma was 2.2/2.64 (US/GER) per million inhabitants and for thymic carcinomas 0.48/0.42. The male-to-female ratio was 1:1.09/1.03, and the mean age 59.48 ± 14.89/61.33 ± 13.94. Individuals with thymomas, but not thymic carcinomas, exhibited a 21%/29% significantly heightened risk of developing secondary malignancies compared to controls with non-thymic primary tumors.

Discussion

This study provides a comparative analysis of anterior mediastinal tumors, particularly TETs, in the US and GER over the past two decades. Furthermore, it highlights a significantly elevated incidence of secondary malignancies in thymoma patients.

The French FRACTURE database: A way to improve knowledge on management of children with very rare tumors

INTRODUCTION

Very rare pediatric tumors (VRTs), defined by an annual incidence ≤2 per million inhabitants, represent a heterogeneous group of cancers. Due to their extremely low incidence, knowledge on these tumors is scant. Since 2012, the French Very Rare Tumors Committee (FRACTURE) database has recorded clinical data about VRTs in France. This study aims: (a) to describe the tumors registered in the FRACTURE database; and (b) to compare these data with those registered in the French National Registry of Childhood Cancer (RNCE).

METHODS

Data recorded in the FRACTURE database between January 1, 2012 and December 31, 2018 were analyzed. In addition, these data were compared with those of the RNCE database between 2012 and 2015 to evaluate the completeness of the documentation and understand any discrepancies.

RESULTS

A total of 477 patients with VRTs were registered in the FRACTURE database, representing 97 histological types. Of the 14 most common tumors registered in the RNCE (772 patients), only 19% were also registered in the FRACTURE database. Total 39% of children and adolescent VRTs registered in the RNCE and/or FRACTURE database (323 of a total of 828 patients) were not treated in or linked to a specialized pediatric oncology unit.

CONCLUSION

VRTs represent many different heterogenous entities, which nevertheless account for 10% of all pediatric cancers diagnosed each year. Sustainability in the collection of these rare tumor cases is therefore important, and a regular systematic collaboration between the FRACTURE database and the RNCE register helps to provide a more exhaustive picture of these VRTs and allow research completeness for some peculiar groups of patients.

Pediatric Thymoma: A Review and Update of the Literature

Pediatric thymomas are extremely rare and slow-growing malignant tumors. The recent publication of the first Union for International Cancer Control (UICC)/American Joint Committee on Cancer (AJCC) Tumor–Node–Metastasis (TNM) stage classification and updated treatment guidelines for thymomas has prompted us to perform a review of the literature on pediatric thymomas. A search of English-language articles in the PubMed, Cochrane, Web of Science, and Embase databases was conducted. Additional articles were identified through reference lists of retrieved publications. Thirty-two articles involving 82 pediatric thymomas were included. Males comprised 60% of patients, and 13% manifested myasthenia gravis (MG). Histotype B1 (45%) and stage I (52% Masaoka–Koga and 71% UICC/AJCC TNM) were the most frequent. Of note is the possibility that the lack of cases with mixed histologies in the reviewed publications might be related to a sampling issue, as it is well known that the more sections are available for review, the more likely it is that the majority of these neoplasms will show mixed histologies. Both staging systems showed a gradual increase in the percentage of cases, with more advanced stages of disease moving from type A to B3 thymomas. Complete surgical resection (R0) was the main therapeutic approach in Masaoka–Koga stage I (89%) and UICC/AJCC TNM stage I (70%) thymomas. Advanced stages of disease and incomplete surgical resection were most often associated with recurrence and death. An association between stage and outcome, and completeness of resection and outcome, was found. Interestingly, though an association between histotype and staging was found, this does not take into account the possibility of mixed histologies which would reduce the clinical impact of histologic subtyping over staging.

The Use of Sunitinib as Maintenance Therapy in a Pediatric Patient With a Poorly Differentiated Thymic Carcinoma

BACKGROUND

Thymic carcinomas are rare aggressive mediastinal tumors with a median survival of 2 years.

OBSERVATION

We present a pediatric patient who was diagnosed with metastatic thymic carcinoma and showed continuous improvement of his primary mass and lung metastases with a regimen of cisplatin/docetaxel followed by long-term maintenance therapy with sunitinib for over 5 years.

CONCLUSIONS

This report demonstrates a long-term positive treatment effect using chemotherapy followed by sunitinib in an advanced thymic carcinoma. We are not aware of other reports of pediatric patients with metastatic thymic carcinoma treated with sunitinib maintenance who maintained a durable response for this prolonged period of time.

Thymic Tumours in Children

Thymomas are very rare neoplasms in children and they represent less than 1% of mediastinal tumours in the paediatric population. The aim of our study was to assess the long-term treatment results of children with thymic tumours. A total number of eight children (four boys and four girls) with thymic tumours were identified. Median age at diagnosis was 7 years. In seven of them, thymoma was diagnosed; in one, a thymic carcinoma was diagnosed. In five of them, the WHO type was assessed: in two of them, the B1 type was found; in one, B2 was found; in one, AB was found, and in one, C was found. In all but one, surgery was the first-line treatment, but six patients had only partial resection. One patient started treatment with chemotherapy and four others received chemotherapy after the surgery. Radiotherapy was applied in six patients, with a median total dose of 37.5 Gy. Follow-up ranged from 8.5 to 273.5 months, with a median of 6.1 years. During this time, four patients died: one due to progression of the disease, and in the other three, the reason for death was unknown. In all evaluated patients, complete regression was observed (100% local control). Two-, 5- and 10-year OS and PFS were 85% and 72%, 51% and 54%, 51% and 54%, respectively. Combined treatment could provide satisfactory results in thymoma patients. There is a need for further, larger studies, which could help to establish optimal management strategies.

Successful Surgical Management of a Rare Combination of Intrapericardial Teratoma and Thymoma in an Infant

Primary cardiac tumors are rare, accounting for <0.2% of all childhood tumors. They can be diagnosed prenatally. Intrapericardial teratoma is a rare benign tumor that presents either due to the mass effect of the tumor or secondary pericardial effusion. Thymus is an important part of the immune system in the pediatric age group. Thymic lesions are rare causes of anterior mediastinal pathology. Their occurrence in children is rarer, nevertheless knowledge about their pathologies helps in clinching the correct diagnosis. We report a case of combined intrapericardial teratoma and thymoma that has not been reported previously in the literature.

Rare Tumors in Children and Adolescents - the STEP Working Group's Evolution to a Prospective Registry

Background Very rare tumors (VRT) in children and adolescents have such a low incidence that until recently, they have not been integrated into the clinical and scientific network of pediatric oncology. Data is very limited and consistent treatment strategies are missing. Thus, VRTs are classic orphan diseases. To counteract this problem, the Arbeitsgemeinschaft für Seltene Tumorerkrankungen in der Pädiatrie (STEP) was founded. Here we report on patient recruitment during the first 10 years. Patients Patients aged up to 18 years and not included in any other clinical trial or GPOH registry were included in this analysis. Methods Data was collected from 2008 to 2018 by means of a standardized form. The recorded diagnoses were descriptively analyzed focusing on histology, localization, and year of report. Results A total of 623 patients with VRTs were registered. During 2008-2014, the annual number of registrations was around 40 and is around 90 since 2015. Most frequent diagnoses included tumors of the skin (n=150), tumors of the gastrointestinal tract (n=102), tumors of the gonads (n=77), the ENT region (n=68), and miscellaneous tumors (n=107). Discussion With the establishment of central structures for clinical consultation and documentation of VRTs, the number of registrations increased. Comprehensively, VRTs are as common as other classic pediatric oncology tumors, but extremely heterogeneous in terms of localization, histology, and prognosis. By a centralized and complete registration and analysis of VRTs, also in collaboration with international partners, it is possible to develop treatment strategies and thus greatly increase treatment quality.

Congenital thymoma

Thymomas are a heterogeneous group of tumors arising from the epithelium of the thymus. They are categorized by the proportion of neoplastic epithelia to lymphocytes and by the degree of cytologic atypia. Thymomas constitute 0.2-1.5% of all malignancies and nearly all occur in patients over 20 years. We reviewed the available literature and found less than 50 cases of thymoma reported in children (<18 years of age), the youngest being 4 years old, and no cases in newborns. They represent less than 1% of all mediastinal tumors in children. Due to the limited number of cases in the pediatric population, the diagnosis and treatment in this population is extremely challenging. Thymomas in all age groups may be associated with paraneoplastic syndromes, being myasthenia gravis the most common, which is associated with a worse prognosis in the pediatric population. We present the first case of a newborn infant with congenital thymoma. This case demonstrates a rare tumor in an unusual age group and emphasizes the importance of multidisciplinary teamwork in the decision-making and management of this condition.

The European Paediatric Rare Tumours Network - European Registry (PARTNER) project for very rare tumors in children

The PARTNER project (Paediatric Rare Tumours Network - European Registry) was launched in 2016. PARTNER aims to create a European Registry dedicated to children and adolescents with very rare tumors (VRT). It links existing national registries and provides a registry for those countries in which a VRT registry has not yet been created. This consortium is composed of the various national cooperative groups and their respective member institutions. The strategic value of this project is based on the Europe-wide data collection concerning the treatment of VRTs. These data are provided to experts and constitute the basis for new clinical practice guidelines for use by ERN (European Reference Network) and non-ERN institutions. The proposed tasks and milestones will increase collaboration in the field of pediatric oncology among member states and will also facilitate the inclusion of low health expenditure average rate (LHEAR) countries in this process. In addition, this project creates a platform for VRTs that may represent a model on how to elaborate a comprehensive approach (case registration, international case consultation and treatment recommendations, and website to provide information for parents/patients) for rare diseases.

Thymoma and thymic carcinoma in children and adolescents: The EXPeRT/PARTNER diagnostic and therapeutic recommendations

Thymic tumors are epithelial tumors arising from the anterior mediastinum and constitute 0.2-1.5% of all adult malignancies but are exceptional in pediatric population. Thymic epithelial tumors (TETs) encompass a variety of histologic subtypes associated with different clinical outcomes. Due to its rarity in children, TETs' management requires a multidisciplinary approach. However, prognosis remains still poor, especially among patients with thymic carcinoma. This study presents the internationally recognized recommendations for the diagnosis and treatment of thymic tumors in children and adolescents, established by the European Cooperative Study Group for Pediatric Rare Tumors (EXPeRT) group within the EU-funded project Paediatric Rare Tumours Network - European Registry (PARTNER).

Facing the challenges of very rare tumors of pediatric age: The European Cooperative Study Group for Pediatric Rare Tumors (EXPeRT) background, goals, and achievements

It has become increasingly clear in recent years that we need to develop ad hoc strategies to combat very rare tumors (VRT) of pediatric age. In 2008, several schemes being run in different countries were pooled together to create the European Cooperative Study Group for Pediatric Rare Tumors (EXPeRT) project: a cooperative study group that aimed to promote research in the relatively uncharted territory of rare tumors of pediatric age. EXPeRT members were able to activate different levels of cooperation to achieve their goals, and to obtain dedicated funding by participating in EU-financed projects. Their experiences emphasize the merits of networking, seeking new partnerships, joining forces, and pooling resources to extend the reach of research efforts, and ultimately improve the quality of patient care. Between 2018 and 2021, the EXPeRT has been active in establishing the Pediatric Rare Tumors Network - European Registry (PARTNER). This project had the main purposes of building a European common registry of pediatric VRT, but also the major task of developing diagnostic and treatment guidelines for VRT (or at least part of them). These clinical recommendations are the subject of a series of papers on Pediatric Blood and Cancer.

Chemotherapy-induced myasthenic crisis in thymoma treated with primary chemotherapy with curative intent on mechanical ventilation: a case report and review of the literature

Background

Thymoma is an uncommon cancer often associated with myasthenia gravis, an autoimmune disorder of the neuromuscular junction characterized by muscular fatigability. In patients with advanced nonmetastatic thymoma, primary chemotherapy may be required to induce tumor shrinkage and to achieve radical resection. Cancer chemotherapy has been anecdotally reported as a trigger factor for worsening of myasthenia gravis in thymic epithelial cancers. The study of uncommon cases of chemotherapy-related myasthenic crisis is warranted to gain knowledge of clinical situations requiring intensive care support in the case of life-threatening respiratory failure.

Case presentation

We report a case of an 18-year-old Caucasian woman with advanced Masaoka-Koga stage III type B2 thymoma and myasthenia gravis on treatment with pyridostigmine, steroids and intravenous immunoglobulins, who developed a myasthenic crisis 2 hours after initiation of cyclophosphamide/doxorubicin/cisplatin primary chemotherapy. Because of severe acute respiratory failure, emergency tracheal intubation, mechanical ventilation, and temporary (2 hours) discontinuation of chemotherapy were needed. Considering the curative intent of the multimodal therapeutic program, we elected to resume primary chemotherapy administration while the patient remained on mechanical ventilation. After 24 hours, the recovery of adequate respiratory function allowed successful weaning from respiratory support, and no further adverse events occurred. After 3 weeks, upon plasma exchange initiation with amelioration of myasthenic symptoms, a second course of chemotherapy was given, and in week 6, having documented partial tumor remission, the patient underwent radical surgery (R0) and then consolidation radiation therapy with 50.4 Gy in 28 fractions in weeks 15–20.

Conclusions

This case report, together with the only four available in a review of the literature, highlights that chemotherapy may carry the risk of myasthenic crisis in patients affected by thymoma and myasthenia gravis. To our knowledge, this is the first reported case of chemotherapy continuation on mechanical ventilation in a patient with chemotherapy-induced myasthenic crisis requiring tracheal intubation. The lesson learned from the present case is that, in selected cases of advanced thymoma, the paradoxical worsening of myasthenia gravis during chemotherapy should not be considered an absolute contraindication for the continuation of primary chemotherapy with curative intent.

Clinical significance of age at diagnosis among patients with thymic epithelial tumors: a population-based study

Background: To investigate the clinicopathologic characteristics and survival outcomes of patients with thymic epithelial tumors (TET) according to age at diagnosis.

Results: A total of 4431 patients were analyzed. Gender, race, tumor histology and surgery were similar between different age groups. The 0-18 group was associated with a higher risk of distant metastasis. Compared to patients aged above 80, the hazard ratios (HR) for patients aged 0-18, 19-30, 31-40, 41-50, 51-60, 61-70, 71-80 were 1.079, 0.739, 0.614, 0.621, 0.633, 0.673, 0.861, respectively. From the subgroup analysis for the adult patients who were above 19 years old, we found that the 19-70 group had significant better cancer specific survival (CSS) and overall survival (OS) than the above 70 group.

Conclusions: Age is a strong independent prognostic factor for survival in TET. Pediatric TET has a higher risk of distant metastasis and an inferior CSS. For the adults who were above 19, patients older than 70-year-old were associated with a shorter CSS.

Methods: Information of 4431 TET patients was retrieved from the Surveillance, Epidemiology, and End Results (SEER) database. Demographic features, clinicopathologic characteristics and survival outcomes were compared between patients diagnosed at different age groups (0-18, 19-30, 31-40, 41-50, 51-60, 61-70, 71-80, above 80).

Pediatric Mediastinal Masses:: Role of MR Imaging as a Problem-Solving Tool

Computed tomography (CT) is the imaging modality of choice for evaluating mediastinal masses detected by radiography or clinical presentation. However, CT results can often be indeterminate. Thoracic magnetic resonance (MR) imaging is a noninvasive way to characterize mediastinal lesions, site of origin, and involvement of adjacent structures by providing higher soft tissue contrast than CT, with superior tissue characterization and higher diagnostic specificity. Thoracic MR imaging of mediastinal masses can increase diagnostic certainty, reduce the number of surgical interventions, and improve clinical decision making. In this review article, current imaging techniques and clinical applications of MR imaging as a problem-solving tool for assessing mediastinal masses in pediatric patients are discussed.

Aplastic Anemia as an Immune-mediated Complication of Thymoma: A Case Report

Thymomas are the most common masses located in the anterior mediastinum, and they are often associated with autoimmune disorders including myasthenia gravis, polymyositis, and aplastic anemia (AA). Autoreactive T-cell clones generated by the thymoma may lead to autoimmune disorders. We report the case of a 14-year-old boy who was examined for AA, and the underlying cause was determined to be an immune-mediated complication of thymoma. He had no matched sibling donors. He underwent thymectomy, and 3 months later he was treated with immunosuppressive therapy (IST), consisting of antithymocyte globulin and cyclosporine A. The duration of the IST was determined to be a period of 12 months. He has recently been in complete response condition for 6 months since IST stopped. IST is a successful treatment choice for thymomas associated with AA in childhood.

Pediatric patients with cutaneous melanoma: A European study

INTRODUCTION

Cutaneous melanoma is rare in childhood and published studies have mainly been retrospective single-institution series or small case series. Given the absence of clinical protocols dedicated to pediatric melanoma, the treatment approach is generally extrapolated from the ones applied to adults.

METHODS

Coordinated by the European Cooperative Study Group for Pediatric Rare Tumors (EXPeRT), this study collected patients prospectively registered between 2002 and 2012 under national cooperative projects dedicated to rare pediatric tumors in Italy, Poland, Germany, and France. Additional cases were collected from dermatology registries in Germany and Israel.

RESULTS

A total of 219 patients aged 0-18 years (median 14.4) were included in the analysis. Sentinel lymph node biopsy was performed in 112 patients (76% of those with Breslow thickness > 0.75 mm) and was positive in 37.5%. Systemic therapy was used in 33 cases. In stage III cases, survival rates were similar for patients who received (23 cases) or not (21 cases) adjuvant therapy. For the whole series, 3-year overall and disease-free survival rates were 91.4% and 84.0%, respectively (median follow-up 41.8 months). Tumor site, tumor stage, and ulceration influenced survival rates. Patients treated by pediatric oncologists (n = 140) were more likely to have advanced disease than those treated by dermatologists (n = 79).

DISCUSSION

This study would suggest that the clinical history of melanoma in children and adolescents might resemble that of adult counterpart. Cooperative efforts are needed to make new drugs more readily available to pediatric patients to increase the outcome of patient with advanced disease.

Outcome and prognostic factors in high-risk childhood adrenocortical carcinomas: A report from the European Cooperative Study Group on Pediatric Rare Tumors (EXPeRT)

OBJECTIVES

The aim of this retrospective international analysis was to evaluate the role of risk factors in pediatric patients with adrenocortical carcinoma (ACC) observed in European countries (2000-2013) in an attempt to identify factors associated with poor prognosis.

PROCEDURES

Data were retrieved from databases of Germany, France, Poland, and Italy, which form the European Cooperative Study Group on Pediatric Rare Tumors (EXPeRT). Patients were less than 18 years old, with at least one of the following tumor-related risk factors: metastases, volume more than 200 cm³ , Cushing syndrome, vascular or regional lymph node invasion, initial biopsy, or incomplete excision. Role of patients' age was also evaluated.

RESULTS

Eighty-two patients were evaluated: 62 with localized disease and 20 with metastases. The 3-year progression-free survival (PFS) and overall survival (OS) were 39% and 55% for the whole population, respectively, and 51% and 73% for localized diseases, respectively. Concerning the whole population, PFS and OS were influenced by distant metastases, tumor volume, lymph node involvement, age, and presence of two or more risk factors. Factors significant only at OS were vascular involvement and incomplete surgery. At multivariable analysis, the main factors at PFS were volume more than 200 cm³ (hazard ratio [HR]: 2.6, 95% confidence interval [CI]: 1.18-5.70) and presence of distant metastases (HR: 8.26, 95% CI: 3.49-19.51). The OS was significantly influenced by the presence of metastases (P < 0.0001). Concerning patients with localized tumors, the only significant prognostic factor was volume more than 200 cm³ with a HR of 4.38 (95% CI: 1.60-12.00) for PFS and of 3.68 (95% CI: 1.02-13.30) for OS.

CONCLUSIONS

Distant metastases and large tumor volume were the main unfavorable prognostic factors. Presence of two or more factors related to ACC was associated with an aggressive behavior of disease.

Correlation between S-1 treatment outcome and expression of biomarkers for refractory thymic carcinoma

BACKGROUND

Thymic carcinoma is a rare cancer with minimal evidence of a survival benefit following chemotherapy. An oral fluoropyrimidine of S-1, however, is the recommended active cytotoxic chemotherapy agent for refractory thymic carcinoma based on a case series, whereas sunitinib or everolimus are recommended as molecular-targeted agents based on Phase II trials. We retrospectively investigated the efficacy of S-1 for refractory thymic carcinoma and performed a biomarker analysis.

METHODS

We assessed the clinicopathological variables of 14 consecutive patients who underwent S-1 for refractory thymic carcinoma and correlated the clinical outcomes with potential biomarkers using paraffin-embedded cancer tissues of eight patients in the cohort.

RESULTS

A total of 178 thymic malignancies were identified, of whom 14 patients included 12 cases of squamous cell carcinoma, one lymphoepithelioma-like carcinoma, and one undifferentiated carcinoma. Six patients exhibited a partial response (42.9 %: 95 % confidence interval [CI], 21.4-67.4) and the disease control rate was 85.7 % (60.0-96.0 %). After a median follow-up of 24.2 months, the median progression-free survival was 8.1 months (range, 2.6-12.2 months), and median overall survival was 30.0 months (range, 6.2-41.9 months). No significant correlation between biomarker expression and response was noted. However, thymidine synthase (TS)/dihydropyrimidine dehydrogenase and TS/orotate phosphoribosyltransferase were observed.

CONCLUSIONS

S-1 for refractory thymic carcinoma offered clinical activity and achieved an 85 % disease control rate. Although the biomarkers did not correlate with clinical outcome, the study results showed efficacy of S-1 as a cytotoxic chemotherapy for refractory thymic carcinoma, which warrants future investigation.

CHEST PAIN DUE TO A GIANT THYMOMA IN AN ADOLESCENT BOY

Chest pain in children is a common referral for emergency examination, although it is believed that the underlying condition is not a serious event. The authors present the case of a 17 years old male with complaints of chest pain with a very recent onset, constant, experienced after physical effort. All medical history and physical examination findings were normal, the poster-anterior chest X-ray revealed a heterogenous opacity in the middle third of the right hemithorax confirmed on computerized tomography as a large solid anterior mediastinal mass with a diameter of 7.5/10.3 cm. By thorax surgery the mass was identified in the anterior and superior mediastinum and total resection was achieved for the tumor mass and thymus. Pathology examination showed poor small and medium epithelial cells proliferation and the tumor was classified as thymoma type 1B. Mediastinum is a rare location of space occupying processes in children. Also, there is a high rate of asymptomatic lesions in this area, considering that half of them are incidentally discovered for various chest X ray examinations. Many causes of chest pain in children are benign; nonetheless, some serious events do exist sometimes and pediatricians must pay attention to identify and manage those cases.