Differentiation between rebound thymic hyperplasia and thymic relapse after chemotherapy in pediatric Hodgkin lymphoma.

BACKGROUND: Rebound thymic hyperplasia (RTH) is a common phenomenon caused by stress factors such as chemotherapy (CTX) or radiotherapy, with an incidence between 44% and 67.7% in pediatric lymphoma. Misinterpretation of RTH and thymic lymphoma relapse (LR) may lead to unnecessary diagnostic procedures including invasive biopsies or treatment intensification. The aim of this study was to identify parameters that differentiate between RTH and thymic LR in the anterior mediastinum. METHODS: After completion of CTX, we analyzed computed tomographies (CTs) and magnetic resonance images (MRIs) of 291 patients with classical Hodgkin lymphoma (CHL) and adequate imaging available from the European Network for Pediatric Hodgkin lymphoma C1 trial. In all patients with biopsy-proven LR, an additional fluorodeoxyglucose (FDG)-positron emission tomography (PET)-CT was assessed. Structure and morphologic configuration in addition to calcifications and presence of multiple masses in the thymic region and signs of extrathymic LR were evaluated. RESULTS: After CTX, a significant volume increase of new or growing masses in the thymic space occurred in 133 of 291 patients. Without biopsy, only 98 patients could be identified as RTH or LR. No single finding related to thymic regrowth allowed differentiation between RTH and LR. However, the vast majority of cases with thymic LR presented with additional increasing tumor masses (33/34). All RTH patients (64/64) presented with isolated thymic growth. CONCLUSION: Isolated thymic LR is very uncommon. CHL relapse should be suspected when increasing tumor masses are present in distant sites outside of the thymic area. Conversely, if regrowth of lymphoma in other sites can be excluded, isolated thymic mass after CTX likely represents RTH.

Hiperplasia tímica de rebote posquimioterapia en niños con linfoma / Rebound (reactive) thymic hyperplasia after chemotherapy in children with lymphoma

Introducción: Se ha descrito la regeneración del timo tras la quimioterapia en niños con linfoma y, para evitar diagnosticar incorrectamente estos casos como recurrencias, los facultativos han de familiarizarse con la hiperplasia tímica de rebote (HTR) y tener en consideración su posible ocurrencia. Nuestro objetivo fue estimar la prevalencia de HTR en niños con linfoma tras la quimioterapia y evaluar las características clínicas, evolución y hallazgos de las pruebas de imagen mediante tomografía computarizada (TC) y la gammagrafía con galio 67 (GA-67). Pacientes y métodos: Estudio retrospectivo transversal, mediante la revisión de las historias clínicas de niños diagnosticados de linfoma, realizado en la Clínica Ambulatoria de Oncología Infantil del Centro de Oncología de Yeda, Arabia Saudita. Resultados: Se detectó HTR en el 51,9% de los pacientes con linfoma (14/27 pacientes). La HTR ocurrió una mediana de 2,5 meses tras finalizarse el tratamiento (rango: 2,0-4,25 meses). Los pacientes con HTR recibieron tratamientos significativamente más cortos, y no se observaron diferencias entre pacientes con y sin HTR en cuanto al sexo, la edad al diagnóstico, el tipo de linfoma o el tipo de tratamiento recibido. Todos los pacientes con HTR se encontraban asintomáticos y las pruebas rutinarias de laboratorio no evidenciaron alteraciones. La TC y la GA-67 fueron altamente sugestivas de HTR. Ninguno de los pacientes con HTR tuvieron recurrencias y la HTR se resolvió espontáneamente en una mediana de 6 meses (rango: 4,0-11,0 meses). Conclusión: Se detectó HTR en alrededor del 50% de los niños con linfoma tras completarse el tratamiento. La evaluación clínica, pruebas de laboratorio, TC y gammagrafía con GA-67 resultan útiles para identificar la HTR y descartar otras lesiones en otras localizaciones

Introduction: Thymic regrowth after chemotherapy treatment has been reported in children with lymphoma, and in order to avoid misdiagnosing these cases as relapses, physicians should become familiar with rebound (reactive) thymic hyperplasia (RTH) and remain aware of its possible occurrence. We aimed to estimate the prevalence of RTH in children with lymphoma after completion of chemotherapy and to evaluate the clinical characteristics, outcomes, and the findings of computed tomography (CT) and gallium-67 (GA-67) scans in these patients. Patients and methods: We conducted a retrospective cross-sectional study by reviewing the health records of children with a lymphoma diagnosis managed at an outpatient paediatric oncology clinic in Jeddah, Saudi Arabia. Results: Rebound thymic hyperplasia was detected in 51.9% of the lymphoma patients (14/27). It developed a median of 2.5 months after completion of chemotherapy (range, 2.0-4.25 months). Patients with RTH had significantly shorter treatment durations, and we found no significant differences between patients with and without RTH in sex, age at diagnosis, type of lymphoma or type of treatment received. All patients with RTH were asymptomatic, and routine laboratory tests did not detect any abnormalities in them. The findings of CT and GA-67 scans were highly suggestive of RTH. None of the patients with RTH had a recurrence, and RTH resolved spontaneously within a median of 6 months (range, 4.0-11.0). Conclusion: RTH was detected in ∼50% of children with lymphoma after completion of chemotherapy. A clinical evaluation and laboratory tests combined with imaging by CT and GA-67 can help identify RTH and rule out other lesions elsewhere

[Rebound (reactive) thymic hyperplasia after chemotherapy in children with lymphoma]. / Hiperplasia tímica de rebote posquimioterapia en niños con linfoma.

INTRODUCTION: Thymic regrowth after chemotherapy treatment has been reported in children with lymphoma, and in order to avoid misdiagnosing these cases as relapses, physicians should become familiar with rebound (reactive) thymic hyperplasia (RTH) and remain aware of its possible occurrence. We aimed to estimate the prevalence of RTH in children with lymphoma after completion of chemotherapy and to evaluate the clinical characteristics, outcomes, and the findings of computed tomography (CT) and gallium-67 (GA-67) scans in these patients. PATIENTS AND METHODS: We conducted a retrospective cross-sectional study by reviewing the health records of children with a lymphoma diagnosis managed at an outpatient paediatric oncology clinic in Jeddah, Saudi Arabia. RESULTS: Rebound thymic hyperplasia was detected in 51.9% of the lymphoma patients (14/27). It developed a median of 2.5 months after completion of chemotherapy (range, 2.0-4.25 months). Patients with RTH had significantly shorter treatment durations, and we found no significant differences between patients with and without RTH in sex, age at diagnosis, type of lymphoma or type of treatment received. All patients with RTH were asymptomatic, and routine laboratory tests did not detect any abnormalities in them. The findings of CT and GA-67 scans were highly suggestive of RTH. None of the patients with RTH had a recurrence, and RTH resolved spontaneously within a median of 6 months (range, 4.0-11.0). CONCLUSION: RTH was detected in ∼50% of children with lymphoma after completion of chemotherapy. A clinical evaluation and laboratory tests combined with imaging by CT and GA-67 can help identify RTH and rule out other lesions elsewhere.

A tri-modal distribution of age-of-onset in female patients with myasthenia gravis is associated with the gender-related clinical differences.

BACKGROUND: A tri-modal distribution of age-at-onset emerged among females patients with myasthenia gravis (MG) in our database. This finding may be indicative of different gender-based disease mechanisms. METHODS: We retrospectively reviewed the files of 127 MG patients for the clinical, serology and thymus pathology according to their age at disease onset: ≤40 years (early-onset, EOMG), 40-70 years (intermediate-onset, IOMG) and >70 years (late-onset, LOMG). RESULTS: EOMG was more common among females, and IOMG was more common among males. Ocular MG was more common among the male MG patients with an IOMG. Patients with EOMG had lower rates of positive anti-acetylcholine receptor (anti-AChR). IOMG females, but not IOMG males, had lower rates of positive anti-AChR. IOMG and EOMG females had high rates of thymic hyperplasia, while EOMG males had high rates of thymoma. Comorbidity with autoimmune diseases was common among females with IOMG and LOMG. CONCLUSIONS: The prevalence of IOMG was the reason for the trend reversal of MG prevalence between genders. The clinical features of patients with IOMG differed between genders in the rates of positive anti-AChR, follicular hyperplasia of the thymus and comorbidity with autoimmune diseases. This may suggest a different gender-based mechanism of immune intolerance towards AChR and other antigens.

Predictors for reactive thymic hyperplasia and its prognostic value in children and adolescents with lymphoma.

BACKGROUND: Reactive thymic hyperplasia (RTH) is seen in children and adolescents receiving chemotherapy for various malignancies. However, it is not clear why this occurs only in some patients. The aim of this study was to identify the predictors for RTH in children and adolescents receiving chemotherapy for lymphoma and to determine the effect of RTH on prognosis. METHODS: We reviewed the medical records of 126 lymphoma patients (October 2007-October 2012). The patients were divided into two groups according to different criteria, i.e., age at initial diagnosis (2-12 years vs. 13-18 years); presence of thymic infiltration at baseline (yes vs. no); and receipt of mediastinal radiotherapy (yes vs. no). The Kaplan-Meier method and multivariate Cox regression model analysis were used to analyze predictors for RTH. Further, patients were divided into two groups according to the occurrence of RTH during follow-up, and Kaplan-Meier survival analysis was used to analyze the prognostic value of RTH. RESULTS: The 2-12-year-old group had a shorter duration from the end of therapy to RTH than the 13-18-year-old group (median: 3 months vs. 16 months) and a higher rate of RTH (97.1% vs. 60.3%, P < 0.001). The lymphoma thymic non-infiltration group had a shorter duration from the end of therapy to RTH than the lymphoma infiltration group (median: 4 months vs. 22 months), and a higher rate of RTH (88.2% vs. 57.6%, P < 0.001). The non-mediastinal radiotherapy group had higher rate of RTH than the mediastinal radiotherapy group (84.7% vs. 12.5%, P < 0.001). Low age, absence of thymic infiltration by lymphoma at baseline, and absence of mediastinal radiation were predictors for RTH by multivariate Cox regression analysis (P < 0.05). The RTH group had a lower recurrence rate than the non-RTH group (13.9% vs. 40%), and a longer duration from the end of therapy to recurrence (median: 10 months vs. 5 months, P < 0.001). CONCLUSIONS: Younger age, absence of thymic infiltration by lymphoma at baseline and absence of mediastinal radiotherapy are predictors for RTH in children and adolescents. RTH may be a positive prognostic factor.

[An enlarged thymus associated with Graves' disease]. / Een vergrote thymus bij ziekte van Graves.

BACKGROUND: Thyrotoxicosis and orbitopathy are the best-known expressions of Graves' disease. There are also rarer and less-known phenomena, such as thymic hyperplasia. Identification of these is important in order to avoid potentially unnecessary invasive interventions. CASE DESCRIPTION: In the case of two young women with lung embolisms, CT pulmonary angiography also revealed an enlarged thymus. This turned out to be caused by as of yet unknown Graves' disease. Since pathological examination of a thymus-biopsy sample was unable to rule out thymoma, thymectomy was performed on the first patient. Pathological examination of the entire thymus revealed hyperplasia. Additional FDG-PET/CT scan of the second patient revealed diffuse hyperactivity in the diffusely enlarged thymus. In this case, we opted for expectant treatment. A follow-up FDG-PET/CT scan 1 year later, revealed a non-abnormal thymus. CONCLUSION: An enlarged thymus caused by thymic hyperplasia is a less well-known manifestation of Graves' disease. In case additional abnormalities develop in patients with Graves' disease, it is important to consider that these might be related to the disease before diagnosing an additional new condition.

Modified unilateral video-assisted thoracoscopic extended thymectomy for myasthenia gravis using 5-mm incisions: A case report.

RATIONALE: Myasthenia gravis (MG) is the most common cause of acquired neuromuscular junction disorder. Thymectomy has been established as an effective therapy for MG, as it attenuates the natural course of the disease and may result in complete remission. PATIENT CONCERNS: We report the case of a 22-year-old female with a 6-year history of MG presented with bilateral ptosis, diplopia, and intermittent dysphagia. She denied shortness of breath, dysarthria, and fatigue. DIAGNOSES: She had been diagnosed with MG 6 years previously at the Neurology Department of our hospital. A computed tomography (CT) scan revealed thymic hyperplasia INTERVENTIONS:: She was treated with modified unilateral VATET that minimized incision size. OUTCOMES: Unilateral VATET was performed using two 5-mm incisions to minimize pressure on intercostal soft tissues/nerves and reduce postoperative pain. LESSONS: The lesson learnt from this case report is that this modified VATET method could be a useful approach to the management of non-thymomatous MG. The ability to achieve complete dissection with good cosmetic results may lead to wider acceptance of this technique by patients with MG and their neurologists for earlier thymectomy and improved outcomes. Additional studies are needed to determine the superiority of this approach to established methods.

miR-548k regulates CXCL13 expression in myasthenia gravis patients with thymic hyperplasia and in Jurkat cells.

Myasthenia gravis (MG) is a B cell-mediated and T cell-dependent autoimmune disease. Thymic hyperplasia has great significance for MG pathogenesis and treatment. MicroRNAs (miRNAs) are a newly recognized type of gene expression regulatory factor that regulate gene expression at the post-transcriptional level. Additionally, miRNAs are involved in immune regulation of the thymus and the occurrence and development of autoimmune diseases. In this study, we found 33 miRNAs that were significantly dysregulated in thymic tissues from MG patients with thymus hyperplasia (MGH) compared with thymic tissues from normal controls using a miRNA microarray chip. We found a negative correlation between the miR-548k and CXCL13 mRNA levels in a large set of samples using quantitative real-time polymerase chain reaction (qRT-PCR). We found that the CXCL13 3'-untranslated region (UTR) was a target of miR-548k using bioinformatics analysis. Next, we obtained direct evidence that CXCL13 is a target of miR-548k using a luciferase reporter assay. Finally, we demonstrated negative regulation between mir-548k and CXCL13 in Jurkat cells. Thus, miR-548k regulates the mRNA expression of its target gene CXCL13 in the thymus of MGH patients and plays an important role in MGH pathogenesis.

Rebound thymic hyperplasia after adrenalectomy in a patient with Cushing syndrome caused by adrenocortical adenoma: A case report.

RATIONALE: The development of rebound thymic hyperplasia (RTH) has been reported in patients who have recovered from stressful conditions such as surgery and steroid therapy. We report a case of RTH following the resolution of hypercortisolism after adrenalectomy for the treatment of adrenocortical adenoma in a patient with Cushing syndrome. PATIENT CONCERNS: A 5-month-old female infant with a history of overeating, hirsutism, and excessive weight gain for the previous 2 months was referred to the hospital. The laboratory results revealed elevated 24-hour urinary free cortisol levels. An overnight dexamethasone suppression test showed no response. Abdominal imaging revealed a right-sided suprarenal mass measuring 4_3cm. Histology showed an adrenocortical adenoma. Thus, she underwent a right adrenalectomy. DIAGNOSES: The patient showed clinical improvement with weight loss and normal cortisol levels over the next 4 months. Six months after the operation, a chest computed tomography showed enlargement of the left thymic lobe, which was previously nonexistent. INTERVENTIONS: A fine needle aspiration biopsy was performed, and histological examination revealed diffuse thymic hyperplasia. OUTCOMES: At the 1-year follow-up, the chest imaging studies showed resolution of the RTH. LESSIONS: An understanding of RTH after adrenalectomy as a treatment for cortisol-producing adrenocortical tumors is important for the prevention of unnecessary surgical intervention and therapy.

The thymidylate synthase enhancer region (TSER) polymorphism increases the risk of thymic lymphoid hyperplasia in patients with Myasthenia Gravis.

BACKGROUND: Myasthenia Gravis (MG) is caused, in approximately 80% of the patients, by autoantibodies against the nicotinic acetylcholine receptor (AChR). The disease is often associated with pathological changes of the thymus: thymic epithelial tumours are present in about 10-20% of the patients, while up to 80% of the patients with early disease onset have thymic hyperplasia. Folate metabolism is required for the production of DNA precursors and for proper DNA methylation reactions, and impaired folate metabolism has been often associated with cellular growth and cancer. METHODS: We investigated if major polymorphisms of folate-related genes, namely MTHFR c.677C>T, MTR c.2756A>G, MTRR c.66A>G and TYMS TSER (a 28-bp tandem repeat in the 5' promoter enhancer region of TYMS) increase the risk of pathological changes of the thymus in AChR+ MG patients. A total of 526 AChR+ MG patients, including 132 patients with normal (involuted) thymus, 146 patients with thymic hyperplasia, and 248 patients with a thymoma were included in the study. Allele and genotype comparisons were performed among the three study groups, after correcting for multiple testing. RESULTS: The frequency of the TYMS TSER 3R allele was significantly higher in MG patients with thymic hyperplasia (P=0.004), and the TYMS TSER 3R3R genotype was significantly associated with increased risk of thymic hyperplasia [OR 2.71 (95% CI: 1.34-5.47)]. CONCLUSIONS: The 3R allele in the thymidylate synthase promoter enhancer region results in increased protein production, required for the synthesis of DNA precursors. The present study suggests that the TYMS TSER 3R allele increases the risk of thymic lymphoid hyperplasia in AChR+ MG patients.

Thymic Hyperplasia Associated with Graves' Disease: Pathophysiology and Proposed Management Algorithm.

BACKGROUND: The association between Graves' disease (GD) and thymic hyperplasia (TH) was first described in 1912 and has been reported numerous times thereafter. TH associated with GD presents as an incidental mediastinal mass on chest X-ray or computed tomography (CT). The pathogenesis of TH in the setting of GD is unclear but seems to involve a complex interplay of hormonal and immunological mechanisms. SUMMARY: Here, the effect that thyroid hormones and autoimmunity have on thymic growth and size is reviewed. The authors' experience, along with a review of published case reports, reveals that general physicians may be unfamiliar with this association. This lack of familiarity may result in an aggressive management course, including surgical intervention, along with its associated risks and costs. The differential diagnosis and diagnostic workup of thymic enlargement associated with GD is discussed in light of the available clinical evidence. CONCLUSION: Recent literature confirms the generally benign nature of TH associated with GD, and supports a conservative approach for the diagnostic workup and initial management. Practical management recommendations for thymic enlargement associated with GD have been formulated and are presented here.

Graves' Patient with Thymic Expression of Thyrotropin Receptors and Dynamic Changes in Thymic Hyperplasia Proportional to Graves' Disease Activity.

Thymic hyperplasia is frequently observed in Graves' disease. However, detectable massive enlargement of the thymus is rare, and the mechanism of its formation has remained elusive. This case showed dynamic changes in thymic hyperplasia on serial computed tomography images consistent with changes in serum thyrotropin receptor (TSH-R) antibodies and thyroid hormone levels. Furthermore, the patient's thymic tissues underwent immunohistochemical staining for TSH-R, which demonstrated the presence of thymic TSH-R. The correlation between serum TSH-R antibody levels and thymic hyperplasia sizes and the presence of TSH-R in her thymus suggest that TSH-R antibodies could have a pathogenic role in thymic hyperplasia.