Pediatric thymomas: report of two cases and comprehensive review of the 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.

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.

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.

Mediastinal thymoma: A difficult diagnosis in the pediatric age

Thymoma is a rare neoplasm of the anterior mediastinum, which originates from the epithelium of the thymic gland; it occurs mainly in middle-aged adults and is much less common in children. The tumor has slow growth and is asymptomatic in most pediatric cases, thus resulting in an accidental discovery; one-third of the young patient presents symptoms related to the compression of the tumor mass on the surrounding anatomic structures and/or related to paraneoplastic syndromes. Surgery is the treatment of choice and complete resection of the thymoma achieves excellent long-term results in terms of disease-free survival. In this article, we report the clinical case of a 21-month-old girl who came to our observation for persistent cough for over a month investigated with a chest X-ray, performed in another hospital. The X-ray showed an extensive opacification of the left hemithorax with contralateral dislocation of the mediastinum. The instrumental investigations carried out in our hospital (ultrasound, computed tomography, and magnetic resonance of the chest) showed a voluminous expansive mass of the left antero-superior mediastinum, which occupied the entire ipsilateral hemithorax and not dissociable from the thymus. At the histologic examination, the mass resulted to be a B1 thymoma with a low degree of malignancy according to the histologic classification of thymic tumors of the World Health Organization.

Genomic alterations in thymoma-molecular pathogenesis?

Thymomas and thymic carcinomas (TCs) are neoplasms of thymic epithelial cells. Thymomas exhibit a low mutational burden and a few recurrently mutated genes. The most frequent missense mutation p.(Leu404His) affects the general transcription factor IIi (GTF2I) and is specific for thymic epithelial tumors (TETs). The clinically indolent types A and AB thymomas express the miRNA cluster C19MC. This miRNA cluster known to be the largest in the human genome, is-with expression otherwise restricted mostly to embryonal tissue-silenced in the more aggressive type B thymomas and TCs. Thymomas associated with the autoimmune disease myasthenia gravis (MG) exhibit more frequent gene copy number changes and an increased expression of proteins homologous to molecules that are targets for autoantibodies. TCs, however, display a higher mutational burden, with frequent mutations of TP53 and epigenetic regulatory genes and loss of CDKN2A. The knowledge of molecular alterations in TETs fosters the understanding of their pathogenesis and provides guidance for further studies that may lead to the development of targeted therapies.

Open versus thoracoscopic thymectomy for juvenile myasthenia gravis

BACKGROUND

Juvenile myasthenia gravis (JMG) is an antibody mediated autoimmune disorder that manifests as progressive voluntary muscle weakness and fatigue. In medically refractory cases, thymectomy has been shown to abrogate symptoms and reduce glucocorticoid dependence. While transcervical or transsternal incisions have been the traditional approach, adult trends now favor thoracoscopic thymectomy. Little data exist to support this approach in children.

METHODS

A retrospective review of all patients younger than 20 years of age who underwent a thymectomy for JMG at two pediatric institutions between 2001 and 2018 was performed. Children were divided into either an open (transcervical or transsternal) or thoracoscopic group and baseline characteristics, perioperative, and postoperative outcomes were compared.

RESULTS

Thirty-four thymectomies were performed during the 18-year study period; 18 via an open and 16 via a thoracoscopic approach. The operative time was shorter for open procedures compared thoracoscopic ones (108 ± 49 and 145 ± 43 min, respectively, p = 0.025). Thoracoscopic thymectomy was associated with less intraoperative blood loss (5.5 ± 6.0 vs 55 ± 67 ml, p = 0.007), decreased duration of postoperative intravenous narcotic use (5.0 ± 1.5 vs 20 ± 23 h, p = 0.018), and a shorter length of hospitalization (1.7 ± 1.0 vs 2.7 ± 1.1 days, p = 0.009). No perioperative complication occurred in either group. Clinical improvement was reported in 94% of children in both groups.

CONCLUSIONS

Thoracoscopic thymectomy in children is a safe and effective surgical technique for the treatment of JMG. Increased acceptance of this minimally invasive approach by children, families, and referring neurologists may enable earlier surgical intervention.

TYPE OF STUDY

Clinical research paper.

LEVEL OF EVIDENCE

III.

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).

The Role of a Good Quality Autopsy in Pediatric Malpractice Claim: A Case Report of an Unexpected Death in an Undiagnosed Thymoma

Thymomas are extremely rare in the first 20 years of life, with different clinical presentations: from asymptomatic mediastinal masses to compressive and paraneoplastic syndromes. In pediatric population, the respiratory disorders have a higher incidence. The overall thymoma mortality rate is described as 40% and metastasized tumors are more aggressive. This case report describes a compressive syndrome caused by a thymoma in which symptoms were exacerbated by a concurrent pulmonary infection, thus leading an affected infant to sudden death despite medical treatment. In this case, patient's death occurred just before the differential diagnostic process got completed. Malpractice claim was based on the missing diagnosis as well as the suspect of inadequate provided care. Consequently, autopsy played a crucial post-mortem role to find out the cause of death, and to exclude any professional liability. Despite modern diagnostic techniques, autopsies are still the best available forensic tool. It is useful to remember that death is a fact of life, therefore not always preventable.

Spine Metastasis of Thymic Carcinoma in a Pediatric Patient: A Case Report and Comprehensive Literature Review

INTRODUCTION

Thymic carcinoma metastases of the spinal column are very rare, especially in pediatric patients. To our knowledge, this is the first such pediatric case in the literature.

CASE PRESENTATION

We report the case of a 14-year-old male patient with T12 and L1 metastases of thymic carcinoma. He had history of thymectomy and intrathoracic tumor resection 7 months previously. The patient's neurological condition deteriorated; therefore, tumor resection and decompression of the spinal canal were performed. He underwent instrumentation and fusion procedures to prevent spinal instability.

CONCLUSION

The main purpose of the treatment is gross total resection of the thymic carcinoma. However, adjuvant methods such as radiotherapy and chemotherapy should be added to the treatment protocol in patients who have higher stage diseases or those in whom total tumor resection cannot be achieved.

Vitamin K Deficiency Presenting in an Infant with an Anterior Mediastinal Mass: A Case Report and Review of the Literature

We report a case of a 1-month-old infant with spontaneous thymic hemorrhage secondary to severe vitamin K deficiency. He was brought to medical attention due to scrotal bruising and during evaluation was noted to be tachypneic and hypoxemic. Chest X-ray revealed an enlarged cardiothymic silhouette, and a follow-up echocardiogram revealed a mass in the anterior mediastinum. Routine laboratory work-up revealed severe coagulopathy. Further questioning revealed the patient had not received prophylactic vitamin K at birth. The coagulopathy resolved with administration of vitamin K, and a biopsy confirmed the anterior mediastinal mass was due to spontaneous thymic hemorrhage.

[Thymoma in childhood. A case report and review of literature]

BACKGROUND

Mediastinal tumours in children are rare. Around 25% of them can be malignant. The thymoma is an uncommon neoplasm, and during adulthood it corresponds to 30% of anterior mediastinum tumours. The peak incidence is between 55-65 years.

CLINICAL CASE

A case of lymphocytic thymoma case is reported in a 4 year old patient with no previous or associated symptomatology. There was only a volume increase on the anterior neck region. The neck radiography and neck and chest tomography confirmed an anterior mediastinal mass surrounding the aorta and vena cava, as well as multiple mediastinal lymph nodes

CONCLUSIONS

Early diagnosis and complete resection are the basis for management and prognosis.

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.