Efficiency of ectopic thymectomy by three surgical approaches in non-thymomatous myasthenia gravis

Detecting ectopic thymus in thymoma-associated myasthenia gravis through flow cytometry analysis of CD3mediumTCRvβmediumCD4+CD8+ T cells and its clinical significance

Background

Traditional histological methods for identifying ectopic thymus (ET) have significant limitations including high risk of false negatives. This study aims to evaluate the effectiveness of flow cytometry in detecting ETs in patients undergoing total thymectomy.

Methods

We analyzed 864 samples from 103 patients using flow cytometry and hematoxylin and eosin (H&E) staining. ETs were identified by the presence of CD3mediumTCRvβmediumCD4+CD8+ T cells in flow cytometry or Hassall's corpuscles in H&E staining.

Results

In the discovery set, flow cytometry detected ETs in 69.2% of samples, compared to 23.6% by histological methods. The validation set showed a higher incidence of ETs in myasthenia gravis (MG) patients than in non-MG patients (73.5% vs. 58.0%, P < 0.0001) and in those with thymic epithelial tumors versus normal thymus (68.1% vs. 58.1%, P = 0.0088). MG patients exhibited a higher prevalence of active ETs, characterized by a high proportion of CD4+CD8+ T cells, indicating robust thymopoiesis, compared to those without MG (P = 0.0001). Specific regions, such as the left cervical root, areas along the right and left phrenic nerves, and the left innominate vein, showed significantly higher activity (P < 0.05). Additionally, ETs were more frequently found in the cervical region than in the mediastinum (75.0% vs. 60.8%, P = 0.0012), and in patients aged 40 years or younger compared to those older than 40 years (73.0% vs. 60.6%, P = 0.0027).

Conclusions

Flow cytometry is a viable alternative for ET detection, providing a novel distribution map that enhances surgical decision-making in MG treatment.

Choosing the proper path: outcomes of subxiphoid vs. lateral intercostal approaches in the resection of anterior mediastinal masses

Background

While the subxiphoid approach (SA) in thoracoscopic thymectomy offers benefits in terms of fat removal and pain reduction, it remains unclear which patients with anterior mediastinal masses benefit most from the subxiphoid vs. the lateral intercostal approach (LA).

Methods

This retrospective study analyzed patients treated for anterior mediastinal masses at our center from January 2019 to December 2023. Patients were categorized into two groups based on the surgical approach: SA (35 cases) and LA (56 cases). Demographic data, clinical characteristics, perioperative metrics, and short-term outcomes were compared.

Results

Ninety-one patients were included, with diagnoses including thymic cysts (43), thymomas types A, AB, and B1 (24), B2 thymomas (18), thymic carcinoma (6).No significant differences were found between the groups in terms of gender, age, tumor size, body mass index, conversion to sternotomy, or blood loss. The LA group, however, experienced shorter surgical durations (P < 0.001), less drainage (P = 0.021), shorter hospital stays (P < 0.001), and lower hospitalization costs (P = 0.024). Pain scores on the visual analogue scale were similar between groups on the day of surgery and the first postoperative day.

Conclusion

The findings suggest that the lateral intercostal approach is preferable for patients with thymic cysts and Masaoka stage I-II thymomas without myasthenia gravis due to its efficiency and cost-effectiveness.

Enigmatic thymus: Variations in anatomical localisation of thymic tissue as an easily misdiagnosed congenital anomaly in surgical practice

We point out the issue of differential diagnosis regarding the finding of ectopically localised thymic tissue (a thymic cyst) in the neck. Thymic tissue can be found anywhere along its developmental tract of descent, from the angle of the mandible to the upper mediastinum. Disruption of the thymic descent can result in ectopically/abnormally localised islets of accessory thymic tissue, which may undergo cystic changes, as described in a case report by Sun et al. This anatomical variation of the thymus may be clinically misinterpreted as a neoplasm or other congenital anomalies as a branchial cyst, lymphatic malformation or cystic hygroma. The present editorial focuses on the challenge of establishing a diagnosis of ectopically localised tissue of thymus often presented as a lateral cervical mass, especially in the case of cystic variation/degeneration of this thymic tissue. We summarise hypotheses on the origin of such congenital cervical thymic cysts from the point of view of evolutionary history and embryology. We also discuss lesser-known facts about the anatomy, histopathology and developmental biology of the thymus as one of the most enigmatic organs in the human body.

Is a subxiphoid approach equivalent to midline sternotomy for extended thymectomy for achieving disease remission in patients with myasthenia gravis?

A best evidence topic in cardiac surgery was written according to a structured protocol. The question addressed was 'In patients with myasthenia gravis undergoing extended thymectomy, is a subxiphoid approach equivalent to midline sternotomy for achieving disease remission?' Altogether 106 papers were found using the reported search, of which 5 represented the best evidence to answer the clinical question. The authors, journal, date and country of publication, patient group studied, study type, relevant outcomes and results of these papers are tabulated. Five studies of a total of 803 patients with myasthenia gravis (MG) reported their experience with thymectomy by subxiphoid approach versus thymectomy by midline sternotomy. These studies demonstrated shorter operation duration, reduced intraoperative blood loss, reduced hospital length of stay and lower postoperative pain scores in the subxiphoid group. There was no significant difference in rates of postoperative MG crisis between the 2 groups, and similar rates of improvement in quantitative myasthenia gravis scores. We conclude that while further high-quality research is required, thymectomy by subxiphoid approach for MG may be considered in preference to midline sternotomy due to improved short-term postoperative outcomes and similar disease remission rates.

Thymectomy in myasthenia gravis

PURPOSE OF REVIEW

Thymectomy has long been used in the treatment of patients with myasthenia gravis and antibodies against the acetylcholine receptor. However, its effectiveness has only been proven a few years ago in a randomized controlled trial in patients under the age of 65. Here, we review the current literature focusing on patient subgroups, potential biomarkers for outcome prediction and the choice of surgical approach.

RECENT FINDINGS

Long-term follow-up studies after thymectomy confirmed that the benefits regarding clinical outcome parameters and a reduced need for immunosuppressive treatment persist. Nevertheless, a substantial proportion of patients in real-world cohorts do not reach complete stable remission after thymectomy indicating that the underlying autoimmune process is sustained in the periphery. Our understanding of the responsible mechanisms has improved with recent studies. Presently, outcome data after thymectomy in several patient subgroups, such as those aged over 50 years, those with juvenile onset or those with purely ocular symptoms are limited and have been the focus of recent research activities. Similarly, biomarkers guiding an appropriate patient selection for thymectomy are under investigation. A number of cohort studies demonstrated that minimal invasive surgical techniques such as extended robotic thymectomy lead to similar positive outcomes as a transsternal approach with potentially fewer short-term adverse effects.

SUMMARY

Thymectomy is an effective treatment option in adult patients with early onset acetylcholine-receptor positive myasthenia gravis but uncertainty remains with regard to certain patient subgroups.

Clinical Application of Thoracoscopic Resection of Anterior Mediastinal Tumors under the Xiphoid Process

Objective

To explore the feasibility and advantages of thoracoscopic resection of anterior mediastinal tumors through subxiphoid and lateral thoracic approaches.

Method

74 patients with anterior mediastinal tumors hospitalized in our hospital from January 2019 to January 2022 were retrospectively analyzed. They were divided into the lateral chest group (31 cases) and the infraxiphoid group (43 cases) according to different operation methods. The tumor size, operation time, intraoperative bleeding, postoperative pain score, postoperative complications, postoperative drainage tube removal time, and hospital stay were compared between the two groups.

Result

The intraoperative bleeding and postoperative pain scores in the subxiphoid group were better than those in the lateral chest group. There was no significant difference in operation time and postoperative complications between the two groups.

Conclusion

Compared with the lateral thoracic approach, the thoracoscopic subxiphoid approach can be more safe and effective in resectioning anterior mediastinal tumors.