Surgical treatment of thymic cysts and neoplasms in children

Cervical thymic remnants in children

OBJECTIVE

Define the clinical presentation, diagnostic value of preoperative imaging, surgical management, and outcomes of treatment of congenital cervical thymic remnants in children.

DESIGN

Retrospective cohort.

SETTING

Single tertiary care institution.

PATIENTS

20 children who underwent excision of cervical thymic remnant, 1975-2006.

MAIN OUTCOMES MEASURED

Utility of preoperative imaging to diagnose cervical thymic anomalies; success of surgical treatment of cervical thymic remnants.

RESULTS

A total of 20 children were identified, with an average age of 6.98+/-5.63 years. All ectopic thymus tissue was found in the embryonic distribution area associated with the third branchial pouch. Fourteen patients underwent excision of a cystic ectopic thymus. Four of these patients exhibited lesions isolated to the cervical region, and 10 patients displayed lesions involving cervicomediastinal areas. Six patients underwent excision of solid ectopic cervical thymus, and each of these was an unanticipated mass encountered during surgical dissection for other procedures. 83% of patients with solid ectopic cervical thymus presented at age 3 or younger. Physical exam and preoperative imaging correctly diagnosed thymic remnants in 15% patients. Resection of thymic remnants was successful in all patients, and there were no recurrences.

CONCLUSIONS

Though rare, thymic remnants should be considered in the differential diagnosis of masses presenting in locations associated with derivatives of the third branchial pouch. Though preoperative imaging is helpful in identifying the extent of these lesions, congenital thymic remnants prove difficult to diagnosis radiologically. Surgical excision is the diagnostic and therapeutic treatment of choice in the management of cervical thymic remnants.

Cervical thymic cysts

Thymic cysts are rare embryonic remnants along the course of thymic migration in the neck or the anterior mediastinum which may result in cervical masses in children, often misdiagnosed. We present the experience gained by three European tertiary care medical centers in the treatment of thymic cysts as well as the current data on the embryology, clinical presentation, diagnosis and management of thymic cysts. A retrospective study was carried out in nine patients with thymic cysts during the period 1986-2002 at the departments of Pediatric Surgery of Children's University Hospital "Federico II" and "Santobono" Pediatric Hospital of Naples in Italy and "Aghia Sophia" Children's Hospital of Athens in Greece. All cases were asymptomatic, appearing mainly as masses resembling branchial cyst or lymphatic malformation. Laboratory and imaging investigations were not useful for preoperative diagnosis. In one case the mass extended into the mediastinum. The histological findings of thymic tissue and Hassal's corpuscles in the cystic wall were diagnostic. In all cases, surgery was successful and uneventful. Surgical excision was accomplished by dissection of the cystic masses from the jugular vein, carotid artery and vagus nerve and from the sternocleidomastoid muscle. The presence of a normal thymus in the mediastinum must be documented preoperatively in order to avoid the risk of total thymectomy. If a cervical thymic cyst extends into the normal thymus, attempts should be made to preserve the thymus, especially in younger patients. Thymic cysts should always be included in the differential diagnosis of lateral cervical masses, especially in children.

Cervicomediastinal Thymic Cyst: Report of a Case

Congenital thymic cysts are rare. Consequently, they are often misdiagnosed and not included in the preoperative differential diagnosis of neck masses. We report the case of a 7-year-old boy with a large cervicomediastinal thymic cyst to increase the awareness of this unusual entity. We discuss the clinical features, presentation, and pathogenesis of thymic cysts.

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.

Cervicomediastinal thymic cysts

Cervical thymic cysts are among the rarest congenital neck masses. They are probably more frequent than the number of cases reported as many of these lesions are asymptomatic and only discovered incidentally. The initial embryologic development of the thymus begins in the neck, followed by migration into the superior mediastinum. For this reason, extension of cervical thymic anomalies into the mediastinum is possible. Although it is the least common lateral cystic neck mass, it must be differentiated from other pediatric cystic neck masses, the majority of which are anomalies of the branchial system. Due to the possibility of mediastinal extension, the management of these lesions is different than other congenital neck masses. We report two cases of thymic anomalies with mediastinal extension and review the embryology, diagnosis, and management of cervicomediastinal thymic cysts.

Treatment of pediatric malignant thymoma: long-term remission in a 14-year-old boy with EBV-associated thymic carcinoma by aggressive, combined modality treatment

Malignant thymoma, including thymic carcinoma, is extremely uncommon in the pediatric population. It is known to have a very poor outcome. We report on a 14-year-old boy with Epstein-Barr virus (EBV)-associated thymic carcinoma. Sections of the original tumor were analyzed for EBV by in situ hybridization to confirm the histological diagnosis of a lymphoepithelioma-like subtype. High copy numbers of EBV RNA were detected in the tumor tissue, suggesting an etiological role of EBV in our case. Intensive treatment resulted in long-term remission over 12 years. In order to facilitate the difficult management of the rare child with malignant thymoma, a literature search was initiated. Forty well-documented pediatric cases of malignant thymoma were found in the literature. Histological characteristics, clinical features, and therapeutic regimens were reviewed. Having the very limited experience with malignant thymoma in childhood in mind, it is concluded that its aggressiveness makes the most intensive treatment necessary. Long-term remission can be achieved by application of radical surgery, high-dose irradiation, and multiagent chemotherapy. The combination of cisplatinum, etoposide, and ifosfamide seems to be promising.

Disseminated mediastinal carcinoma with chromosomal translocation (15;19). A distinctive clinicopathologic syndrome

BACKGROUND

A case of disseminated mediastinal carcinoma probably of thymic origin is reported in a 5-year-old boy with an anterior mediastinal mass associated with superior vena cava obstruction, tracheal deviation, right malignant pleural effusion, and evidence of bone metastasis. The diagnosis was based on findings of radiologic localization, light and electron microscopic study, and immunohistochemistry. The patient received combination chemotherapy but died of progressive disease.

METHODS

Cytogenic study on the pleural fluid was attempted, and a literature search for similar chromosomal aberration was performed.

RESULTS

Cytogenetic study of tumor cells from the pleural fluid revealed a clonal chromosomal abnormality of t(15;19)(q12;p13.1). Two patients with similar disease were reported in the English literature; their clinical courses, immunohistochemical findings, and t(15;19) were almost identical to those of the patient reported in this study.

CONCLUSION

The authors suggest that this translocation may be specific to thymic carcinoma and may indicate a particularly aggressive form of the disease. Carcinomas are rare in children, so the chromosomal translocation may serve as a helpful marker for the diagnosis.

Paediatric thymoma: unusual occurrence in two siblings

Invasive cystic thymoma is reported in two siblings (an 11-year-old girl and a 9-year-old boy) and the radiographic, CT and ultrasonographic features are described. The tumours were removed by thoracotomy. Familial thymic masses are reviewed, and the imaging differential diagnosis of cystic anterior mediastinal mass in a child is discussed.

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.

Mediastinal masses in childhood: a review from a paediatric pathologist's point of view

From 1970 to 1989, 121 children with mediastinal masses of various sorts were seen in the Department of Pathology, Royal Children's Hospital, Melbourne. The series is considered representative of the true incidence of these conditions in the state of Victoria, which had an average paediatric population during the time of this series of 900,000 children. The commonest cause of a mediastinal mass was NHL (36 cases). This was followed by HD (24 cases), then neuroblastoma and ganglioneuroma (16 and 9 cases respectively), duplication cysts (10 cases), teratomas (7 cases), neurofibroma (4 cases) and lymphangioma (3 cases). A great variety of rare conditions made up the remainder of the series and included mediastinal abscess, thymic cyst, pericardial cyst, accessory lobe of lung, plasma cell granuloma, fibromatosis, paravertebral Ewing's tumour, carcinoid tumour and neurofibrosarcoma. Presentation of the children with NHL was often acute with respiratory distress, while the child with HD was usually older and symptoms were more often systemic than local. The surgeon's role in diagnosis of these most frequently encountered mediastinal masses can be crucial and biopsy when indicated must be carried out with great care to produce material that is adequate for diagnosis and for the performance of cell marker studies and chromosome analysis. Neuroblastoma (NBL) and ganglioneuroma (GN) together were the third largest group. Children with neuroblastoma were usually young; 15 of the 18 cases were less than 2 years old. One-third of the infants with neuroblastoma presented with paraplegia and one-third with respiratory symptoms including wheeze, stridor and respiratory difficulty. Three children had Horner's syndrome. Prognosis of children with thoracic neuroblastoma is very good and contrasts with the poor outlook for those with abdominal neuroblastoma. Stage at presentation is probably the most important single prognostic variable. Ganglioneuroma presents at a later age than neuroblastoma and symptoms may be present for a long time or may be completely absent. Catecholamines, usually raised in neuroblastoma, are mostly normal in ganglioneuroma. Duplication cysts were the next most frequent group. Symptoms can often be acute and life threatening, although in three of our ten cases the cyst was an incidental finding on chest X-ray. However, only three of our patients had a normal respiratory examination. Teratomas were usually large and more often benign than malignant. Excision is the mandatory treatment and is usually curative. Although teratomas in young infants are often cellular and composed of many immature tissue types, their behaviour is benign.(ABSTRACT TRUNCATED AT 400 WORDS)

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.

Hodgkin's disease of the thymus: a rare mediastinal cystic mass

We report a 14-year-old patient referred to us because of chest pain. A huge upper anterior mediastinal mass with several cystic spaces within it was found and resected. Pathologic diagnosis was nodular sclerosis Hodgkin's disease of the thymus. Radiotherapy was started after accurate surgical staging, and the patient remains free of disease 24 months later. Cavitation of the gland in Hodgkin's disease of the thymus should be taken into consideration when dealing with upper anterior mediastinal cystic masses in children. Surgery is probably unavoidable in this group of patients and, interestingly, can account in part for the relatively good prognosis in this localized form of the disease.

Infected thymic cyst: an unusual cause of respiratory distress in a child

A 15-month-old male developed acute respiratory distress following a prolonged upper respiratory tract infection. Laboratory and radiological investigations suggested tracheal compression by a malignant anterior mediastinal mass. Following a short course of steroid therapy, urgent exploration of the mediastinum and resection of the mass was carried out; resolution of the airway obstruction was obtained. Histological and bacteriological examination of the lesion revealed it to be a thymic cyst infected by Haemophilus Influenzae with abscess formation. The causes of tracheal compression in childhood are discussed.

Primary malignant thymoma in a 6-year-old boy

Although not uncommon in adults, thymomas are the least common mediastinal tumors in children. The behavior of these tumors in children is partially distinct with a much more rapid course and a poor prognosis. A symptom-free 6-year-old boy was treated for malignant thymoma detected incidentally on a chest X-ray in a school mass examination. At operation, the tumor was found to have already invaded the surrounding tissue. Complete removal at the base of the invasive tumor is the treatment of choice.

Primary anterior mediastinal tumors in children and adults

This review details pertinent anatomical, radiological, pathological, and clinical information regarding primary anterior mediastinal tumors. Although the majority of these lesions are included in one of several subgroups, for example, thymic tumors, teratomas, or thyroid abnormalities, other less common entities will occasionally be encountered by the practicing surgeon. Likewise, there are variations in the frequency distribution of anterior mediastinal lesions in children as opposed to adults. Management of these individual lesions is outlined.

Primary mediastinal tumors in children

Mediastinal masses in children constitute a heterogeneous group of malignant and benign neoplasms. The majority of malignant tumors in our series of 188 children with a mediastinal mass were Hodgkin's and non-Hodgkin's lymphoma (87 patients) arising in the anterior and middle mediastinum. Ganglioneuroma (17) arising in the posterior mediastinum made up the bulk of benign tumors (52). Infants less than 2 yr old presented with symptoms of tracheal compression, whereas older children had fewer symptoms but a far greater likelihood of having a malignancy. In the assessment of patients with mediastinal tumors, the posteroanterior and lateral chest roentgenograms were most often diagnostic, and computed tomography of the chest provided the most information concerning preoperative resectability. The excellent survival of patients with stage I and II Hodgkin's disease reflects the radiosensitivity of the tumor; in our series of 33 patients, survival was not increased by radical resection. Unlike lymphomatous tumors, neurogenic masses should be completely excised. When initial exploration reveals unresectability, biopsy followed by radiation therapy and second-look excision of the tumor can be accomplished. In patients with primary mediastinal sarcomas, total resection should be carried out if possible. In our series, adjuvant radiation therapy or chemotherapy was effective in only 1 of 15 children with sarcoma. Surgical treatment of all mediastinal masses except lymphoma should be complete excision. In cases of suspected lymphoma, cervical or supraclavicular node biopsy can yield adequate tissue for diagnosis.