Thymoma and myasthenia gravis in a 4-year-old child. Case report and review of the literature

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.

A systematic review of paraneoplastic syndromes associated with thymoma: Treatment modalities, recurrence, and outcomes in resected cases

OBJECTIVE

Paraneoplastic syndromes associated with thymomas remain incompletely understood. The objective was to examine the association between surgically resected thymomas and paraneoplastic syndromes over the past half century.

METHODS

A primary PubMed/MEDLINE search was used to identify published articles describing paraneoplastic syndromes associated with thymomas from 1960 to 2019. A secondary search identified additional articles referenced in the articles found in the primary search. Kaplan-Meier and log-rank test were used for time-to-event data analyses.

RESULTS

From 407 articles describing 507 patients, 123 different paraneoplastic syndromes were associated with thymoma. The 5 most common paraneoplastic syndromes were myasthenia gravis, pure red cell aplasia, lichen planus, Good syndrome, and limbic encephalitis. Complete or partial resolution of paraneoplastic syndrome symptoms after surgery was noted in 76% of patients, of whom 21% had a relapse or new paraneoplastic syndrome onset after surgery. The most common adjunctive therapy associated with resolution of paraneoplastic syndrome was corticosteroids (30%). For all patients after surgery, thymoma recurrence was observed in 17% of cases, whereas recurrence of paraneoplastic syndrome was observed in 34% of cases, and both were observed in approximately 11% of cases. The 5- and 10-year overall survivals were 78% and 66%, respectively. Improved overall survival was associated with patients who had total resolution from paraneoplastic syndrome.

CONCLUSIONS

A comprehensive assessment of publications over the past half century suggests that a multimodal treatment approach that includes surgical resection of thymomas is able to achieve paraneoplastic syndrome resolution in a majority of patients. Onset of new paraneoplastic syndromes after surgery is associated with the recurrence of the first paraneoplastic syndrome, and resolution of paraneoplastic syndrome is associated with improved overall survival.

Pediatric thymoma with a difference: report of a case and review of literature

Thymoma represents <1% of all mediastinal tumors in children. Less than 50 cases of pediatric thymoma are reported in the literature. Thymomas are considered to be highly aggressive in pediatric patients, especially when age is <10 years. Paraneoplastic syndromes, of which around 70% are myasthenia gravis, correlate with poor prognosis. In this article, we report a case of a thymoma in an 8-year-old boy, who had favorable histopathology (Masaoka stage I, WHO type B2), despite the presence of young age and necrosis along with absence of myasthenia gravis. We have also reviewed the available literature on pediatric thymoma.

Surgical management of thymic epithelial tumors in children: lessons from the French Society of Pediatric Oncology and review of the literature

PURPOSE

We report the results of a French multicenter retrospective study based on a period of more than 30 years and a review of the literature in order to more clearly define the surgical approach and specific pediatric risk factors.

METHODS

Clinical data of children comprising all histologic subtypes of thymic epithelial tumors (TET) treated between 1979 and 2009 in French pediatric oncology centers were retrospectively analyzed and discussed in the light of a review of all pediatric cases reported in the literature.

RESULTS

Nine cases were identified, corresponding to five females and four males with a median age of 13 years (range: 7.5-17). Histologic subtypes were type AB (n = 1), type B (n = 5) and type C (n = 3). Treatment consisted of tumor resection (4 R0, 4 R1, 1 R2) via right anterior thoracotomy, posterolateral thoracotomy, left thoracoscopy, sternotomy and cervicosternotomy, and/or chemotherapy, mainly cyclophosphamide-doxorubicin-cisplatin (CAP; n = 5), and/or radiotherapy (n = 4). Two patients with TET type C died. All other patients are alive with a median follow-up of 4 years (range: 1.5-20). Review of a total of 93 pediatric cases reported in the literature showed statistically significant associations between less favorable histologic subtypes and male gender (P = 0.012), advanced Masaoka stage (P < 0.001) and quality of resection (P < 0.001) respectively.

CONCLUSIONS

A review of the literature and our series identified several risk factors to take into account in the therapeutically decision. Complete resection through a sternotomy is highly recommended.

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

PURPOSE

Thymomas are rare pediatric malignancies with indolent behavior. There are fewer than 50 reported cases and no comprehensive review. We sought to evaluate our recent experience with pediatric thymomas, and comprehensively review the extant literature.

METHODS

A systematic search of the PubMed database was performed using keywords: "thymoma", "pediatric", "juvenile", "childhood", and "child". Additional studies were identified by a manual search of the reference list.

RESULTS

We report two patients with thymomas. We identified 22 case reports or series that described 48 patients; 62 % were male, 15 % presented with myasthenia gravis. Fifty percent were Masaoka Stage I, 15 % were Stage II, 13 % were Stage III, and 23 % were Stage IV. Four patients with early stage (I or II) disease were treated with adjuvant therapies in addition to surgical excision, while five patients with late stage (III or IV) disease treated with surgical excision alone. Of studies reporting at least 2-year follow-up, survival was 71 %.

CONCLUSION

Pediatric thymomas are rare tumors with a slight male predominance. Wide variations were observed in the treatment of thymomas across all stages. Our review indicates a need for large database and multi-institutional studies to clearly elucidate clinical course, prognostic factors and outcome.

Management of juvenile myasthenia gravis

Juvenile myasthenia gravis is an uncommon autoimmune disorder. Its management is not standardized. Juvenile myasthenia gravis is pathophysiologically similar to myasthenia gravis in adults. However, a number of significant particularities related to race, age at onset, severity, and antibody status complicate the management. We summarize the unique clinical features of juvenile myasthenia gravis and review the therapeutic options.

Thymomas in childhood: 11 cases from a single institution

AIM

Thymomas are rare in children. Our aim was to review clinical and pathologic characteristics and outcome in children with thymomas.

PATIENTS AND METHODS

Between 1979 and 2011, 11 children with thymomas were diagnosed. Hospital files were reviewed for presenting complaints, clinical, radiologic, and other laboratory data, surgical practices, chemotherapy and radiotherapy outcomes.

RESULTS

Median age was 8 years (range, 1 to 13 y). Male to female ratio was 9/2. Most common initial complaints were dyspnea, cough, chest pain, and fever. Median time from onset of symptoms was 1 month (range, 0.23 to 3 mo). Associated conditions including hyper-IgE syndrome, hypogammaglobulinemia, and systemic lupus erythematosus plus idiopathic thrombocytopenic purpura were present in 3 patients. Chest x-rays and/or thoracic computed tomographies displayed thymic hyperplasia and/or masses in anterior mediastinum accompanied by pleural (n = 2) and pericardial effusions (n = 1), pulmonary metastases (n = 1), and cervical lymph node metastasis (n = 1). Compression or invasion of trachea or vessels was documented in 5 cases. Seven cases underwent initial tumor resection; others experienced open or trucut biopsies. Histopathologically, 5 cases had invasive and 6 had benign thymomas. Benign thymomas did not receive any postoperative treatment; all cases are disease free at a median follow-up of 211 months. Three of 5 cases with invasive thymomas underwent surgery, 4/5 received chemotherapy and external radiotherapy (3600 to 4500 cGy). Two invasive thymomas died of disease. Three cases with invasive thymomas are disease free at a median follow-up of 209 months.

CONCLUSIONS

Benign thymomas have excellent prognosis. For invasive thymomas with or without metastasis, radiotherapy, and chemotherapy offers survival advantage. Complete surgical resection may increase chances for cure.

Childhood-onset myasthenia gravis with thymoma

Juvenile myasthenia gravis is an acquired, autoimmune disease occurring before age 16 years. Thymoma is exceedingly rare in children, especially in association with juvenile myasthenia gravis. We describe a 14-year-old boy with juvenile myasthenia gravis and thymoma. He presented with difficulties chewing and swallowing, nasal speech, and fluctuating weakness of the leg muscles. Neurologic examination revealed masticatory and bulbar muscle weakness with nasal speech, proximal muscle weakness, fatigability of the arms and legs, and distal muscle weakness of the legs. A diagnosis of juvenile myasthenia gravis was confirmed by a positive neostigmine test, a decremental response on repetitive nerve stimulation, and increased titers of serum anti-acetylcholine receptor antibodies. The patient received anticholinesterases, corticosteroids, azathioprine, and thymectomy. A pathohistologic analysis of the thymus gland indicated thymoma, Masaoka grade II. After 2 years of an unstable disease course, remission was achieved. Because only 10 cases of thymoma-associated myasthenia gravis are described in the pediatric population, this report offers an important contribution to a better understanding of this rare association.

Invasive thymoma in a child: a rare case report

Thymomas are neoplasms of the anterior mediastinum and generally occur between the fourth and sixth decades of life. In children, they are rare, with few reported cases. We describe a 9-year-old boy with invasive thymoma treated successfully by surgery alone. The patient was previously healthy and under treatment for a community-acquired pneumonia. A chest radiograph showed an opacity at the left lung base, and thoracic computed tomographic scan showed a mass with thick walls and liquid content situated in the lingula with no cleavage plane with the mediastinum. The patient underwent a left anterolateral thoracotomy, which showed a mass extending from the anterior mediastinum, infiltrating the left upper lobe of lung, phrenic nerve, and pericardium. A left upper lobectomy and resection of the mediastinal mass and lymph nodes were carried out. The pathologic analysis showed it to be a type B3 fusiform-cell thymoma, infiltrating the left upper lobe and 1 peribronchial lymph node. A multidisciplined tumor group decided to observe the patient and followed with thoracic computed tomographic scans every 3 months. After 2 years of follow-up, the patient has no evidence of recurrent disease.

Thymoma in children: report of 2 cases and review of the literature

Thymoma is an uncommon and slow-growing neoplasm. It is derived from thymic epithelial cells and comprises about 20% to 30% of mediastinal masses in adults, but only about 1% in pediatric patients. Patients usually present with mass-associated respiratory symptoms, superior vena cava syndrome, or paraneoplastic syndrome including myasthenia gravis, pure red cell aplasia, or acquired hypogammaglobulinemia, and connective tissue disorders. Due to the limited number of cases, knowledge, and experience with thymoma in pediatric patients, the diagnosis and treatment are very challenging for this age group. In this article, we report 2 cases of thymoma in childhood and provide a comprehensive review and analysis of the reported pediatric cases in the past 30 years (total of 32 cases). We found that patients younger than age 10 years were predominantly male (M:F = 6:1) and had advanced tumor stage more frequent than patients older than age 10 (P = .03). There were also significant associations of male sex with more advanced tumor stage and less favorable outcome (P = .03). These findings suggest that age and sex may be additional potential prognostic contributors in pediatric patients with thymoma. The clinicopathologic features, differential diagnosis, and current therapeutic recommendations of this uncommon tumor in pediatric patients are also addressed.

Thymoma associated with myasthenia gravis in infancy

Thymomas are associated with various autoimmune disorders in adults, most commonly with myasthenia gravis (MG). In MG antibodies developed against acetylcholine (ACh) receptors, resulting weakness of muscle after repeated use and recovery following a period of rest. However, MG due to thymoma is extremely rare in pediatric age group. We report an infant with MG due to invasive thymoma.

[Malignant thymoma associated with severe aplastic anaemia]

Malignant thymoma is a very rare neoplasm in paediatric patients; it is usually associated with para-neoplastic syndromes, the most frequent is myasthenia gravis; some haematological abnormalities may also be present, such as pure red cell aplasia or aplastic anaemia. We report a 12-year-old boy suffering from a very large thymoma, treated with multiple chemotherapy, and who developed a severe aplastic anaemia after surgery. He had a poor response to immunosuppressive treatment and later developed massive pulmonary bleeding as a complication.

Thymoma in the offspring of a patient with Isaacs syndrome

Thymoma is a diagnosis most often made in adults, and is exceedingly rare in children. The diagnosis of a thymoma is often times linked to an autoimmune process, and the association of thymoma and myasthenia gravis in children has been previously reported. We present the first description of a child of a parent with Isaacs syndrome (congenital or acquired neuromyotonia) presenting with a thymoma. In our patient, an evaluation of underlying disease led to a presumptive diagnosis of congenital Isaacs syndrome. This case demonstrates that for the rare child diagnosed with thymoma, evaluation for an underlying neurologic disorder should be considered.

Cystic thymoma in a child: a rare case and review of the literature

Thymomas are rare mediastinal tumors in pediatrics and cystic thymoma, is characterized by a predominantly cystic formation, is extremely rare. This report describes a 13-year-old girl with cystic thymoma, who was treated by video-assisted thoracoscopic surgery. The microscopic findings were characteristic of cystic thymoma. The literature on cystic thymoma is reviewed here and the clinical characteristics of cystic thymoma are discussed.

Thymoma in Children: Report of Two Cases and Review of Literature

Thymoma is an uncommon tumor of childhood. Stage of the tumor is an independent prognostic factor for survival. Surgery is the treatment of choice for stage I and stage II tumors. Chemotherapy is reserved for patients with refractory or metastatic disease. Thymomas are moderately radiosensitive. However, radiation therapy is not an attractive option for children due to its side-effects on developing organs. The authors describe 2 children with completely encapsulated thymoma who were successfully treated with surgery alone. Both patients remain free of disease 3 years after surgery. One of the patients also has nevus sebaceous. The authors also discuss the possible association between the two disease entities.

Germ cell, mesenchymal, and thymic tumors of the mediastinum

Germ cell, mesenchymal, and thymic tumors of the mediastinum are an uncommon and heterogeneous group of neoplasms. Together they account for less than 25% of mediastinal tumors in childhood. The majority of these tumors are found in the anterior and superior mediastinum, but germ cell tumors and mesenchymal tumors may be located in all compartments. They share a broad range of histological subtypes and clinical behavior, tendency to be large in size, and a requirement for complete surgical excision as the major requirement for successful therapy.

Thymoma in childhood: a clinicopathological study of five cases

The histological and clinical findings in five cases of thymoma arising in paediatric patients have been studied. The age range was 11-15 years and no patient was affected by myasthenia gravis. All tumours were macroscopically encapsulated, but two of them displayed evidence of microscopic capsular invasion. Histologically, four cases were of the predominantly cortical type (organoid thymoma) with prominent areas of medullary differentiation and Hassall's bodies; one case was of the cortical type. All patients are alive and disease-free 3 months to 9 years after surgery. These findings suggest that thymoma in the paediatric age group may be characterized by fairly uniform clinicopathological features, with a low rate of association with myasthenia gravis and a favourable prognosis.

Early-onset myasthenia gravis: clinical characteristics and response to therapy

We studied 59 children with myasthenia gravis (MG). Disease onset was pre-pubertal in 26 patients and post-pubertal in 33. The male to female ratio was 0.62 in the early- and 0.17 in the late-onset groups. The frequency of ocular MG was higher in patients with prepubertal onset. Patients with generalized MG generally showed a good response to thymectomy and corticosteroid therapy proved effective with no major side-effects. In our experience early-onset MG has the same course as in adult life. We recommend thymectomy for generalized disease in childhood, except in very young children on account of possible long-term effects on immunological development. Immunosuppressive therapy should be considered in severely affected patients who do not respond adequately to other therapies.

Malignant thymoma in children: a 20-year review

Malignant thymomas are extremely rare in children, with only 27 cases reported thus far in the pediatric surgical literature. We report four additional cases diagnosed at this institution over the past 20 years (ages 3 to 14 years). Clinical presentations included superior vena cava syndrome, cough, dyspnea, cyanosis, enlarging mediastinal mass, spontaneous pneumothorax, and pleuropericardial effusion. Three patients underwent incomplete resection of the mass or biopsy because of "unresectability" and were treated with radiotherapy and adjunctive chemotherapy. One patient underwent near complete macroscopic resection as well as radiotherapy and chemotherapy. All patients died at intervals ranging from 6 months to 2 1/2 years after diagnosis. Three patients were found to have metastatic disease prior to death or at autopsy. In one case, the initial pathological diagnosis was lymphocytic thymoma. After ultrastructural studies were performed, the diagnosis was changed to thymic T-cell lymphoma. This patient subsequently developed acute lymphoblastic leukemia 3 months after surgical resection followed by radiotherapy. Malignant thymomas are highly aggressive tumors in children. A radical surgical approach with complete excision of the tumor and contiguous structures in continuity, with adjunctive radiotherapy and chemotherapy remains the only hope for survival in children with these rare lesions.