The paediatric thymus: recognising normal and ectopic thymic tissue

Post-Thymectomy Autoimmune Flare-Up With New-Onset Type 1 Diabetes Mellitus

The thymus gland aids in the maturation of the immune system. An overactive or malfunctioning thymus gland, as seen in thymomas, can lead to disrupted immune systems. Thymectomy, the usual treatment, can paradoxically lead to further derangements in the immune system, leading to new autoimmune disorders. Most of these reported disorders are rheumatological. Except preclinical studies, there are no reported cases of autoimmune diabetes post-thymectomy. A 25-year-old woman who had malignant thymoma underwent chemotherapy, followed by thymectomy and radiotherapy. She developed autoimmune diabetes mellitus (AID) approximately 1 year post-thymectomy, evident from raised glycated hemoglobin, anti-glutamic acid decarboxylase (GAD) antibodies, ineffectiveness of oral glucose-lowering agents, and positive response to insulin. AID can occur after thymectomy, as evidenced by animal studies and this case report. Whether these patients would have long-term outcomes and control of diabetes differently than classic type 1 diabetes mellitus (T1D) is uncertain. Further research is needed to prove causality between thymectomy and diabetes.

Diffusion-Weighted MR Imaging of the Thymus in Children with Non-Thymic Neoplasms

Purpose: To investigate the diffusion-weighted imaging (DWI) findings and apparent diffusion coefficient (ADC) value of the thymus in children under the age of 13 who have non-thymic neoplasms. Materials and Methods: From January 2021 to April 2023, a single-center retrospective study analyzed consecutive 191 thoracic MRI scans with DWI from 67 children (<13 years) with non-thymic neoplasms. The scans were categorized based on the presence of restricted diffusion on DWI. We analyzed the demographics, laboratory data, and MR findings of the thymus. Statistical differences were assessed using generalized estimating equations. Results: Forty-five percent (86/191) of the scans exhibited restricted diffusion in the thymus: multifocal (n = 65; 76%), focal (n = 19; 22%), and diffuse (n = 2; 2%) patterns. The restricted diffusion group demonstrated higher absolute lymphocyte counts, more prominent thymus sizes, and higher frequency of off-treatment status compared to the unrestricted diffusion group (p>0.05). The mean ADC value across all 191 scans was 1.80 × 10-3 mm2/s. No significant difference was observed in the ADC value related to restricted diffusion patterns, the MRI vendors, or the age at the time of the scan. Conclusions: Restricted diffusion was observed in 45% of the thymus in children with non-thymic neoplasms, with a mean ADC value of 1.80 × 10-3 mm2/s. Recognizing the DWI findings can prevent unnecessary invasive procedures, alleviating concerns for patients and families.

An unusual ectopic thymoma clonal evolution analysis: A case report

Thymomas and thymic carcinomas are rare and primary tumors of the mediastinum which is derived from the thymic epithelium. Thymomas are the most common primary anterior mediastinal tumor, while ectopic thymomas are rarer. Mutational profiles of ectopic thymomas may help expand our understanding of the occurrence and treatment options of these tumors. In this report, we sought to elucidate the mutational profiles of two ectopic thymoma nodules to gain deeper understanding of the molecular genetic information of this rare tumor and to provide guidance treatment options. We presented a case of 62-year-old male patient with a postoperative pathological diagnosis of type A mediastinal thymoma and ectopic pulmonary thymoma. After mediastinal lesion resection and thoracoscopic lung wedge resection, the mediastinal thymoma was completely removed, and the patient recovered from the surgery and no recurrence was found by examination until now. Whole exome sequencing was performed on both mediastinal thymoma and ectopic pulmonary thymoma tissue samples of the patient and clonal evolution analysis were further conducted to analyze the genetic characteristics. We identified eight gene mutations that were co-mutated in both lesions. Consistent with a previous exome sequencing analysis of thymic epithelial tumor, HRAS was also observed in both mediastinal lesion and lung lesion tissues. We also evaluated the intratumor heterogeneity of non-silent mutations. The results showed that the mediastinal lesion tissue has higher degree of heterogeneity and the lung lesion tissue has relatively low amount of variant heterogeneity in the detected variants. Through pathology and genomics sequencing detection, we initially revealed the genetic differences between mediastinal thymoma and ectopic thymoma, and clonal evolution analysis showed that these two lesions originated from multi-ancestral regions.

[Ultrasound of the neck]

Ultrasound examination of the neck organs enables an assessment that in many cases is superior to that of magnetic resonance imaging and computed tomography. Ultrasound is therefore not only a first line or point of care imaging modality but can provide imaging for the concluding diagnosis in cases. Because of the good sonographic accessibility of the majority of the structures of the neck, many technical advances, in particular high-resolution ultrasound and signal post-processing have a major influence on the possibilities of ultrasound. Lymph nodes and salivary glands are the main focus in clinical applications, although other diseases and swellings of the neck can also be clarified with ultrasound. Special applications are ultrasound-guided interventions, e.g., biopsies or the sonographic assessment of peripheral nerves. As in any imaging modality, a comprehensive clinical knowledge is necessary for the diagnostic assessment. Because of constant assessment and thus continuous modification of the examination, ultrasound examinations may only be performed adequately with the appropriate clinical knowledge.

A Neck Mass of Thymic Origin in a Pediatric Patient

In this study, we present the case of a 10-year-old boy with a left-sided neck mass. Although most neck masses in children are non-cancerous, their etiology can be complex, especially in neck masses of congenital origin. The workup of a pediatric neck mass includes imaging and cytopathology. In this case, the histopathology of the excised mass revealed thymic tissue, which helped establish the diagnosis of a thymopharyngeal duct cyst. Thymophayngeal duct cysts, although rare, can be diagnosed preoperatively by characteristic tapering toward the mediastinum. Cytopathology may demonstrate Hassall corpuscles. These unique features can help disentangle the differential diagnoses, which commonly include thyroglossal duct cysts, venolymphatic malformations, and branchial cleft cysts.

Antenatal diagnosis of chorioamnionitis: A review of the potential role of fetal and placental imaging

Chorioamnionitis is present in up to 70% of spontaneous preterm births. It is defined as an acute inflammation of the chorion, with or without involvement of the amnion, and is evidence of a maternal immunological response to infection. A fetal inflammatory response can coexist and is diagnosed on placental histopathology postnatally. Fetal inflammatory response syndrome (FIRS) is associated with poorer fetal and neonatal outcomes. The only antenatal diagnostic test is amniocentesis which carries risks of miscarriage or preterm birth. Imaging of the fetal immune system, in particular the thymus and the spleen, and the placenta may give valuable information antenatally regarding the diagnosis of fetal inflammatory response. While ultrasound is largely limited to structural information, MRI can complement this with functional information that may provide insight into the metabolic activities of the fetal immune system and placenta. This review discusses fetal and placental imaging in pregnancies complicated by chorioamnionitis and their potential future use in achieving non-invasive antenatal diagnosis. This article is protected by copyright. All rights reserved.

Ectopic Cervical Thymic Hyperplasia In A Patient Treated For Hodgkin Lymphoma

True thymic hyperplasia results from stressful situations such as chemotherapy. It commonly presents as an anterior mediastinal mass; cervical location is exceptional. Here we report a case of a cervical true thymic hyperplasia in a 12-year-old girl who had a Hodgkin lymphoma treated by radiotherapy and chemotherapy. She was referred to our department for a left cervical mass. The PET scan showed a hypermetabolic adenopathy. Mediastinal MRI was unremarkable. The patient underwent resection of the cervical mass under general anesthesia. Pathological examination confirmed the diagnosis of a true thymic hyperplasia. The aim of this paper is to illustrate a case of an incidental ectopic cervical thymic hyperplasia in a patient treated for Hodgkin lymphoma.