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.

PD-1 and PD-L1 expression in thymic epithelial tumours and non-neoplastic thymus.

AIMS: We explored the relationships between programmed death-1 (PD-1) and programmed death-ligand 1 (PD-L1) expression and the pathological and clinical features of thymic epithelial tumours and thymic hyperplasia. METHODS: We evaluated PD-1 and PDL-1 expressions within epithelial and microenvironmental components in thymic epithelial tumours (n=44) and thymic hyperplasias (n=8), immunohistochemically. We compared the results with demographic, clinical and histopathological features of the cases. RESULTS: We found 48% epithelial expression and 82.7% microenvironment expression for PD-1 and 11.5% epithelial expression and 34.6% microenvironment expression for PD-L1. There was no PD-1 expression, in either the epithelial or microenvironment, in the thymic hyperplasia group. PD-1 and PD-L1 positivity was more significant in thymic epithelial tumours than thymic hyperplasia. Patients with PD-1-positive microenvironments exhibited significantly shorter mean estimated survival time than their negative counterparts. CONCLUSION: These findings suggest that anti-PD-1 and anti-PD-L1 therapies may benefit patients due to high release of PD-1 and PD-L1 in thymic epithelial tumours.

The distribution of parenchyma, follicles, and lymphocyte subsets in thymus of patients with myasthenia gravis, with special reference to remission after thymectomy.

OBJECTIVE: We sought to examine the distribution of parenchyma, follicles, and lymphocyte subsets in the thymus of patients with myasthenia gravis and to identify determinants of remission after thymectomy. METHODS: Sixty patients with myasthenia gravis who underwent thymectomy were examined. The thymus was divided into upper, middle, and lower parts. The upper part was defined as the superior horn, the lower part as the inferior horn, and the middle part as tissue located between the 2 horns. The percentage of parenchyma was measured morphometrically. The degree of follicular hyperplasia was classified into 5 grades. The densities of CD3+, CD4+, and CD8+ lymphocytes were classified into 5 grades. The remission of myasthenia gravis after thymectomy was examined with those variables in each part of the thymus. RESULTS: The middle part had the highest percentage of parenchyma, the highest grade of follicular hyperplasia, and the highest density of CD3+, CD4+, and CD8+ lymphocytes among the 3 parts (P < .001-.05). The grades of follicular hyperplasia in the middle and lower parts were significantly higher in patients with improvement of myasthenia gravis than in those without (P < .05). The densities of CD3+, CD4+, and CD8+ lymphocytes in the cortex of the middle part were significantly higher in patients with improvement than in those without improvement (P < .01-.05). CONCLUSIONS: The thymus has a heterogeneous distribution of parenchyma, follicles, and lymphocyte subsets. The middle part had the largest parenchyma, the highest grade of follicular hyperplasia, and the highest densities of CD3+, CD4+, and CD8+ lymphocytes among the 3 parts of the thymus. The grade of follicular hyperplasia and the density of these lymphocyte subsets are predictive of improvement in myasthenia gravis after thymectomy.

[Difficulties in establishing the cause of sudden death of a 2-year-old child with thymus hyperplasia]. / O trudnosciach w ustaleniu przyczyny naglego zgonu dwuletniego dziecka z przerostem grasicy.

In the reported case the authors discuss the possible role of thymomegaly in the pathological mechanism of sudden death explaining the observed clinical changes (fainting and cardiac murmurs) as due to pressure exerted by the enlarged thymus on the heart and airways. Sudden death was preceded by ingestion of amidoquine tablet and slight trauma to the head.