Rebound thymic hyperplasia after liver transplantation for a child with biliary atresia; a case report

The thymus gland possesses the ability to regrow in children leading to a newly developed anterior mediastinal mass. This condition may represent a rebound phenomenon during recovery from a stressful event such as post‐chemotherapy and hence was described as RTH. RTH after LT has not been well documented. We are reporting an infant with BA who underwent LT and presented with a symptomless anterior mediastinal mass, detected on follow‐up imaging 6 months thereafter. Surgical partial excision was performed to rule out other differential diagnoses of a solid mass in the anterior mediastinum of an infant particularly lymphoma—that may arise as post‐transplant lymphoproliferative disorder—and teratoma, as well as the other aggressive lesions such as thymoma and thymic carcinoma. The final pathological analysis revealed true thymic hyperplasia, consistent with RTH. The diagnosis of RTH should be considered for a child presenting by anterior mediastinal mass after LT.     

Thymic hyperplasia following treatment for nephroblastoma]

Thymic hyperplasia in response to stress is a well known phenomenon. Thymic hyperplasia has also been described after chemotherapeutic treatment for malignancies in children. CASE REPORT: A three-year-old girl was followed up from the age of 18 months for a left kidney nephroblastoma treated by combination of chemotherapy (vincristin, actinomycin and adriamycin) and surgery. Assessment at the end of treatment was normal. Four months after the end of treatment, pulmonary radiography showed mediastinal enlargement, which was shown to originate in the thymus at thoracic CT scan. A recurrence of the disease was suspected. Biopsy showed thymic hyperplasia without evidence of tumor cells. Mediastinal enlargement then disappeared spontaneously 2 months later. CONCLUSION: Thymic hyperplasia occurring during remission of a cancer treated by chemotherapy is a diagnostic dilemma as it suggests mediastinal reccurence of the disease. Needle aspiration cytology is an appropriate investigation in thymic hyperplasia. No steroid therapy should be used before histologic diagnosis of thymic hyperplasia.     

Thymic Hyperplasia Associated with Graves’ Disease in a 10-year-old Boy

Thymic hyperplasia associated with Graves’ disease is rarely reported in children, although it is not uncommon in adults. Occasionally, an enlarged thymus presents as an anterior mediastinal mass on a radiographic examination. Such patients often undergo invasive procedures such as a thymus biopsy or thymectomy because of suspected malignancy. However, an enlarged thymus with Graves’ disease is known to shrink after treatment with antithyroid drugs. Therefore, recognition of this benign course would avoid unnecessary surgical resection. This report presents the case of a 10-yr-old boy with Graves’ disease complicated with an anterior mediastinal mass. Computed tomography showed a homogenous mass with no invasion into the surrounding tissue. A gallium-67 scintigraphy showed no abnormal uptake. Shrinkage of the mass after treatment with an antithyroid drug (methyl-mercaptoimidazole) supported the diagnosis of thymic hyperplasia with Graves’ disease. This case report illustrates two important points. First, pediatricians should be aware that thymic hyperplasia can coexist with Graves’ disease, even in children. Second, close radiographic assessment would support a diagnosis of thymic hyperplasia and eliminate invasive diagnostic procedures.     

Thymic and adenotonsillar enlargement after successful treatment of malignancies

Anterior mediastinal and adenoid masses in children after cessation of chemotherapy for malignant disease often cause a diagnostic problem. Differential diagnosis of thymic enlargement and adenoid hyperplasia from recurrence frequently poses a challenge both for the radiologist and the physician. In this study the authors evaluated 491 patients with different malignant tumors for thymic and adenoid hyperplasia. Thymic hyperplasia was seen in 18 patients (5 Hodgkin disease (HD), 5 non-Hodgkin lymphoma (NHL), 4 Wilms tumor, 2 germ cell tumor, 1 Ewing sarcoma, and 1 neuroblastoma), only adenotonsillar hyperplasia was seen in 6 patients, all with NHL, and both thymic and adenotonsillar hyperplasia were seen in 3 patients (1 HD, 2 NHL). In 5 patients, adenoid hyperplasia was proven by biopsy; 1 patient underwent to adenoidectomy. Their histopathologic investigation showed polyclonal follicular hyperplasia. The authors recommend that patients with thymic and/or adenotonsillar enlargement after successful treatment of their primary malignancy should be evaluated cautiously before an invasive procedure is planned.     

Computerized tomography and ultrasonographic findings in massive thymic hyperplasia. Case discussion and review of current concepts

Massive thymic hyperplasia in the neonate and young infant can be difficult to diagnose. Differentiation from neoplastic lesions may require thoracotomy for a pathologic specimen. We review a case in a 15-month-old child referred to our institution and discuss the radiographic, ultrasound, and computerized tomographic features of hyperplastic thymic tissue. We review current concepts of the hyperplastic thymus as an anterior mediastinal mass in infancy.     

Thymic rebound following successful chemotherapy of B-lymphoma in an adolescent boy

Four months after termination of successful chemotherapy for epipharyngeal B-non-Hodgkin lymphoma, an enlarging anterior mediastinal mass was discovered in a 15-year-old boy. There was no other suspicion of tumour recurrence. A simple thymic rebound was likely and a conservative management was chosen. Follow up for more than 12 months was uneventful. The frequency of thymic hyperplasia after termination of chemotherapy is discussed. It is a benign immunological rebound phenomenon and does not require operative intervention.     

Diagnosis of anterior mediastinal mass lesions using the Chamberlain procedure in children

The mediastinum is the most common site for primary intra-thoracic pathology in childhood. This paper describes the versatility of the Chamberlain operation in establishing tissue diagnosis and guiding definitive treatment in children with mediastinal mass lesions. During 1999-2006, 28 consecutive patients were referred to a National Oncology Center with anterior mediastinal pathology. Eleven underwent the Chamberlain procedure. Demographic data, diagnostic sensitivity, operating time and morbidity were recorded. All patients had preoperative chest X-ray and computed tomography scans. The Chamberlain operation was deployed in only those children without other ways of accurately establishing their diagnosis. Others with mediastinal pathology had a diagnosis established by lymph node biopsy, thoracentesis or other method(s). Eleven patients (nine male, two female; age range 2-13 years) underwent the Chamberlain procedure. In these children, there was no pre-existent diagnosis and this was the primary procedure employed. Diagnostic accuracy was 100%. Three patients had pleural disruption and chest tubes were placed at the time of surgery. No patient required a thoracotomy. Average operating time was 1.3 h. Five patients were diagnosed with Hodgkin's lymphoma, four had non-Hodgkin's lymphoma and two children thymic hyperplasia. The Chamberlain operation provides excellent access to the antero-superior mediastinum for biopsy of obscure mediastinal mass lesions in childhood. Complications from this procedure are very rare.     

Rebound thymic hyperplasia five years after chemotherapy for Wilms' tumor

Rebound thymic hyperplasia following chemotherapy is well documented, usually occurring within the first year. A delayed presentation makes distinction from an anterior mediastinal mass problematic in view of the increased risk of a second primary malignancy in pediatric cancer survivors. An unusual case of rebound thymic hyperplasia is described, presenting five years after completion of chemotherapy for Wilms' tumors.     

Thymic enlargement in childhood

Thymic masses constitute one of the least common mediastinal masses in childhood. While producing symptoms of airway compromise, they also raise the suspicion of malignancy when detected. Radiological, operative and pathological findings of patients that have been operated for thymic masses in our institution is presented in this paper. Nine patients were operated in our institution during a 12-year-period between 1985-1997 for thymic masses. Ages of the patients ranged from four months to 13 years. With the exception of one, who was diagnosed with a routine chest x-ray, all the patients had respiratory complaints. All the patients had been evaluated with computed tomography preoperatively. In total, seven sternotomies and four thoracotomies were performed to reach the anterior mediastinum. The distribution of masses was as follows two malignant thymomas, three thymic hyperplasia, one lymphocyte-rich thymoma, one epithelial thymoma, one cystic thymoma and one lymphoblastic lymphoma. Although rare, thymic enlargement may be a cause of intractable respiratory complaints in childhood. Because of the high incidence of primary malignancy of the mediastinal neoplasms in childhood, thymic enlargement requires accurate pathological diagnosis and treatment. Median sternotomy with intensive anesthetical care allows proper tumoral exposure.     

Normal thymus simulating pericardial disease: diagnostic value of magnetic resonance imaging.

Normal enlargement of the thymus in infancy can often lead to erroneous clinical suspicion of cardiomegaly. Roentgenographic differentiation is not always definitive but echocardiography is generally effective in differentiating cardiac pathology from an enlarged thymus. In this patient, magnetic resonance imaging was necessary to differentiate benign thymic hyperplasia from pericardial or mediastinal pathology. Thymic involution with a severe neonatal illness, followed by thymic rebound, which later subsided, added to the interest and initial confusion in this patient.     

Combined true thymic hyperplasia and lymphoid hyperplasia in Graves' disease

True thymic hyperplasia (enlarged gland composed of histologically unremarkable cortical and medullary parenchyma) and lymphoid hyperplasia (medullary lymphoid follicles in the clinical setting of autoimmunity) usually develop as independent pathologic processes. We reviewed the clinical features and gross and microscopic pathology of 2 hyperthyroid patients with features of both thymic hyperplasia and lymphoid hyperplasia. The diagnosis of thymic hyperplasia was supported by thymic weights greater than two standard deviations above the mean weight for age and histologic evidence of expanded cortical and medullary parenchyma. The diagnosis of lymphoid hyperplasia was supported by the increased number and size of medullary lymphoid follicles and the association with Graves' disease. This unusual combination results from two separate pathogenic mechanisms operating simultaneously in hyperthyroid patients. Elevated thyroid hormones directly stimulate the proliferation of thymic epithelium, producing thymic hyperplasia. The immune abnormalities underlying Graves' disease can also result in lymphoid hyperplasia of the thymus.     

Combined True Thymic Hyperplasia and Lymphoid Hyperplasia in Grave's Disease

True thymic hyperplasia (enlarged gland composed of histologically unremarkable cortical and medullary parenchyma) and lymphoid hyperplasia (medullary lymphoid follicles in the clinical setting of autoimmunity) usually develop as independent pathologic processes. We reviewed the clinical features and gross and microscopic pathology of 2 hyperthyroid patients with features of both thymic hyperplasia and lymphoid hyperplasia. The diagnosis of thymic hyperplasia was supported by thymic weights greater than two standard deviations above the mean weight for age and histologic evidence of expanded cortical and medullary parenchyma. The diagnosis of lymphoid hyperplasia was supported by the increased number and size of medullary lymphoid follicles and the association with Grave's disease. This unusual combination results from two separate pathogenic mechanisms operating simultaneously in hyperthyroid patients. Elevated thyroid hormones directly stimulate the proliferation of thymic epithelium, producing thymic hyperplasia. The immune abnormalities underlying Grave's disease can also result in lymphoid hyperplasia of the thymus.     

Thymic teratoma or thymic remnant attached to mediastinal teratoma? The cellular origin of mediastinal teratomas revisited.

Thymic tissue can be encountered in about 20 % of mediastinal teratomas. It is found located at the periphery of the teratoma mass. Although rare, mediastinal teratoma arising within the thymus can be seen. It has not been defined yet whether the thymus is an organ simply attached to the teratoma or whether the teratoma arises from the thymus. The authors present here two illustrative cases of mediastinal teratoma, one raised within the thymus and the other closely attached to the thymic remnant, to discuss the cellular origin of mediastinal teratomas.     

Left-sided posterior mediastinal thymus-MRI findings

Anomalous descent of the thymus may result in ectopic thymic tissue in the neck and/or the mediastinum and can mimic an abnormal mediastinal mass. We present one case of a posterior mediastinal mass that was diagnosed as a posterior mediastinal thymus utilizing CT plus MRI.     

Thymic uptake of gallium-67 citrate in a healthy 4 year old boy

Gallium uptake in a mediastinal mass has been most often seen with lymphoma. A case is reported of thymic uptake in an otherwise healthy 4 1/2 year old boy who had recently had pneumonia. Serial films always showed an unchanging prominent though normal thymus and follow up gallium scans showed disappearance of thymic uptake. This and other similar cases indicate the need to consider a non-neoplastic thymus when gallium accumulation is noted in the anterior mediastinum of a child.     

Inspiratory stridor and dysphagia in two newborn infants caused by ectopic thymus tissue

We report two cases of ectopic cervical thymus, a solid thymic lesion, and a thymus cyst causing inspiratory stridor and mild dysphagia in the neonatal period. Because of the rarity of thymic dystopia, the two masses were initially misdiagnosed as more common entities, namely, lymph node enlargement and lymphangioma, respectively. The correct diagnosis was made only after surgical excision and histopathological examination. This case report is completed by a short review of embryogenic development, diagnostic procedures with differential diagnoses, and therapeutic outcome of ectopic thymus.     

Thymic Mucosa-associated Lymphoid Tissue Lymphoma in an Adolescent Girl

Mucosa-associated lymphoid tissue (MALT) lymphoma is very rare in children. We report the first case of pediatric thymic MALT lymphoma in an adolescent Asian girl. She presented with chest pain, dyspnea, and low-grade fever. A large anterior mediastinal mass was biopsied that confirmed the diagnosis of MALT lymphoma with trisomy 18. The patient had secondary immunodeficiency with low NK cell count and high IgA and IgG levels. Because of the advanced stage and the presence of trisomy 18, she was treated with cyclophosphamide, vincristine, prednisone, and rituximab, followed by involved-field radiotherapy. She is currently undergoing maintenance therapy with rituximab and remains in complete remission at 13 months from diagnosis. Thymic MALT lymphoma should be suspected in any Asian child with a cystic thymic mass and autoimmune disease or hyperglobinemia. Because of the slow proliferation rate of this type of lymphoma, a long-term follow-up is needed.     

Undescended thymus presenting as midline neck swelling

A seven month male child presented with midline neck swelling which was visible in the suprasternal notch when the child cried. Computed tomography revealed that it was thymic tissue (solid). There was no thymic tissue in the normal position. Undesended thymus or ectopic thymus is a rare cause of neck mass. Solid type as seen in this case constitute 10% of ectopic thymic tissue ,90% being of cystic variety. Caution should be exercised in excision of such masses as they may be the only thymic tissue.     

Massive true thymic hyperplasia.

A case of massive true thymic hyperplasia in a child of eleven months is described. This rare disorder must be included in the differential diagnosis of a mediastinal mass in children. Diagnosis and management are discussed and the relevant literature is reviewed.     

Childhood mediastinal masses in infants and children

We reviewed all cases of primary pediatric mediastinal masses diagnosed and treated over a 24-year period. In this study, out of 187 primary mediastinal mass cases diagnosed between 1980 and 2004 in Istanbul University Istanbul Faculty of Medicine, Cardiovascular Surgery Department, 37 pediatric primary mediastinal mass cases were retrospectively evaluated according to age, sex, symptoms, diagnostic procedure, anatomical location, surgical treatment, histopathological evaluation and postoperative adjuvant therapy. The patients ranged in age from 2 months to 15 years at the time of diagnosis, with a mean age of 8 years. There were 24 benign (64.8%) and 13 malignant (35.2%) tumors. The cases were lymphoma (27%), neurogenic tumors (21.6%), cystic lesions (18.9%), germ cell tumors (13.5%), thymic lesions (10.8%) and cardiac tumors (8.1%). Complete and partial resections of the tumor were the surgical procedures performed in 24 patients (64.8%) and 3 patients (8.1%), respectively. The three patients with a malignant tumor, in whom the entire mass could not be removed, received chemotherapy and radiation after surgery. In 10 patients with lymphoma, surgery was not a part of treatment and they received medical and radiation therapy after the establishment of the definitive diagnosis. All patients survived and were discharged from the hospital. Except for the cases with lyphoma, all patients are now free of recurrent disease. Compared to adults, children had more lymphomas and neurogenic tumors. Primary pediatric mediastinal malignancies are relatively common in infants and children. Lymphoma, neurogenic tumors and cystic lesions predominated. These differences between the age groups should also be considered when dealing with a mediastinal mass.