A proof-of-concept study: advantages of the subxiphoid over the lateral intercostal approach

OBJECTIVES

The study was designed to evaluate the superiority of the subxiphoid approach comparing with the lateral intercostal approach during the process of operation, and other perioperative indices.

METHODS

Patients diagnosed anterior mediastinal disease in our hospital between January 2018 and October 2019 were prospectively assigned into two groups, receiving the lateral intercostal approach or the subxiphoid approach VATS to resect the disease. The PaCO2, SaO2, PaO2 and circulation changes were recorded during the operation, neutrophil-to-lymphocyte ratio, and other perioperative outcomes, including clinical and surgical results, operation time, blood loss, postoperative complication, postoperative pain score were compared.

RESULTS

A total 59 patients diagnosed anterior mediastinal tumour or myasthenia gravis underwent the resection by VATS. 31 patients were treated with the subxiphoid approach, 28 patients were treated with the lateral intercostal approach. PaCO2 increased significantly and SaO2 remained stable in the subxiphoid group during the operation, while PaCO2 increased significantly and SaO2 decreased at the same time in the lateral intercostal group. Operations were more frequently interrupted for the hypoxia or circulation disturbance during the process of dissecting the thymus in the lateral intercostal approach. Compared with the lateral intercostal approach, patients in the subxiphoid approach experienced less inflammation reaction, and yielded lower pain score and shorter postoperative hospital stay. There were no significant differences in postoperative complications between the two groups. All these patients recovered well when discharged.

CONCLUSIONS

Our study suggested that subxiphoid approach will influence pulmonary and circulation lesser than the lateral intercostal approach, and the whole procedure will be safer and easier, and the subxiphoid approach may be the ideal choice for the anterior mediastinal disease.

Thymoma Exhibiting Spontaneous Regression With Cystic Change Due to Acute Infarction: A Case Report and Literature Review

Spontaneous regression (SR) of thymoma is rare. We report a case of a surgically resected thymoma due to cystic changes owing to acute ischemic infarction with an increased anti-acetylcholine receptor antibody level. A 61-year-old male underwent a computed tomography (CT) scan, which showed a 4.9 cm anterior mediastinal tumor and slight right pleural effusion. Blood test results indicated an elevated white blood cell count of 13300/mL. One month later, an enhanced CT scan at our hospital showed spontaneous mediastinal tumor regression to 3.7 cm and no pleural effusion. The tumor contained homogeneous low-density areas on enhanced CT, which showed high intensity on T2-weighted magnetic resonance imaging, indicating cystic changes. He had no symptoms of myasthenia; however, his anti-acetylcholine receptor antibody level was slightly elevated (0.4 nmol/L). Suspecting a thymoma, an extended total thymectomy through a median sternotomy was performed. Histopathological analysis confirmed the diagnosis of thymoma type B2 and Masaoka stage I. SR is due to acute intratumoral infarction. At two years postoperatively, no tumor recurrence or development of myasthenia gravis was observed. Thymomas should be included in the differential diagnosis of anterior mediastinal tumors that regress spontaneously with cystic changes, pleural effusion, and an elevated inflammatory response. Mature cystic teratoma rupture should be differentiated, but preoperative biopsy is often challenging owing to necrotic and fibrous tissues; therefore, early surgical resection is required for diagnosis and treatment.

Robot-assisted thymectomy in large anterior mediastinal tumors: A comparative study with video-assisted thymectomy and open surgery

BACKGROUND

The aim of this study was to evaluate the safety and effectiveness of robot-assisted thymectomy (RAT) in large anterior mediastinal tumors (AMTs) (size ≥6 cm) compared with video-assisted thymectomy (VAT) and open surgery.

METHODS

A total of 132 patients with large AMTs who underwent surgical resection from January 2016 to June 2022 were included in this study. A total of 61 patients underwent RAT, 36 patients underwent VAT and 35 patients underwent open surgery. Perioperative outcomes were compared.

RESULTS

There were no significant differences in tumor size (p = 0.141), or pathological types (p = 0.903). Compared with the open group, the RAT and VAT groups were associated with a shorter operation time (115.00 vs. 160.00, p = 0.012; 122.50 vs. 160.00, p = 0.071), and less blood loss (50.00 vs. 200.00, p < 0.001; 50.00 vs. 200.00, p < 0.001), respectively. The rate of conversion in the RAT group was similar to that in the VAT group (6.56% vs. 13.89%, p = 0.229). Concomitant resection was less frequently performed in the VAT group than in the RAT and open groups (5.56% vs. 31.15%, p = 0.040; 5.56% vs. 31.43%, p = 0.006). VAT patients had a lower drainage volume (365.00 vs. 700.00 and 910.00 mL, p < 0.001), shorter duration of chest tube (2.00 vs. 3.00 and 4.00, p < 0.001), and shorter hospital stay (5.00 vs. 6.00 and 7.00, p < 0.001) than the RAT and open groups. There was no 30-day mortality in any group. No difference was seen in R0 resection rates (p = 0.846). The postoperative complication rates were similar among the three groups (p = 0.309). Total in-hospital costs (66493.90 vs. 33581.05 and 42876.40, p < 0.001) were significantly higher in the RAT group.

CONCLUSIONS

RAT is safe and effective for the resection of large AMTs compared to VAT and open surgery. Vascular resection in RAT is technically feasible. A long-term follow-up is required.

Quantitative analysis of metabolic parameters at 18F-fluorodeoxyglucose positron emission tomography in predicting malignant potential of anterior mediastinal tumors

To evaluate the utility of ¹⁸F-fluorodeoxyglucose (FDG)-positron emission tomography (PET) for predicting the malignancy of anterior mediastinal tumors, the present study retrospectively examined a total of 105 consecutive patients who underwent surgical resection of anterior mediastinal tumors at Gunma University Hospital after undergoing a preoperative FDG-PET scan. Patients were divided into benign and malignant groups in accordance with the following three classification systems: i) Clinical classification, benign or malignant (thymoma and carcinoma); ii) recurrence-based classification, low-risk recurrence (benign and low-risk thymoma) or high-risk recurrence (high-risk thymoma and carcinoma); and iii) pathological classification, benign (benign and thymoma) or malignant (carcinoma). The present study analyzed the differences between the benign and malignant groups in terms of FDG-PET parameters, including maximum standardized uptake value (SUVmax), metabolic tumor volume (MTV) and total lesion glycolysis (TLG). The malignant group exhibited a significantly greater SUVmax than the benign group according to all classification systems. By contrast, there was only a slight difference between groups in volume-based metabolic parameters (MTV and TLG) using the clinical classification, and no intergroup differences using the recurrence-based and pathological classifications. The area under the curve in receiver-operating characteristic curve analysis for predicting malignancy was significantly greater for SUVmax than for volume-based metabolic parameters using all classification methods. The respective optimal cut-off value, sensitivity and specificity of SUVmax to predict malignancy were 1.77, 92.0 and 87.0% for the clinical classification, 2.54, 93.6 and 60.3% for the recurrence-based classification, and 5.15, 78.9 and 90.7% for the pathological classification. SUVmax was the most useful parameter for predicting the malignancy of anterior mediastinal tumors.

Thyroid Storm and Incidental Anterior Mediastinal Teratoma: Coincidence or Correlation?

Teratoma is a rare cause of thyrotoxicosis. Among the different types of teratoma, struma ovarii is the main type which contains thyroid tissue. There is no evidence in the literature that would indicate mediasternal teratoma would also lead to thyrotoxicosis or thyroid storm. Herein we report a 37-year-old woman who suffered from palpitation. Her chest X-ray showed a mass lesion at the left hilum, and chest computed tomography scan yielded a suspicion of pericardial cyst. Thereafter, video-assisted thoracoscopic surgery was performed, and thymic cyst was diagnosed during the operation. However, subsequent pathological studies confirmed a diagnosis of mature cystic teratoma. A thyroid function test demonstrating hyperthyroidism was completed prior to the patient's operation, and thyroid storm was diagnosed by clinical presentation. The patient's symptoms did not improve after the operation until we added beta blocker and anti-thyroid agents. Therefore, was the presence of thyroid storm and anterior mediastinal teratoma coincident or correlative in this case? The special stain of teratoma tissues did not reveal any thyroid tissues. In conclusion, thyroid storm and anterior mediastinal teratoma in our case occurred coincidentally. However, a survey of possible hyperthyroidism in patients with anterior mediastinal tumor before operation is critical to avoid perioperative complications.

KEY WORDS

Anterior mediastinal tumor; Hyperthyroidism; Teratoma.