Clinical features, diagnosis and thoracoscopic surgical treatment of thymic cysts

Robotic surgery for thymic cysts: clinical features, management, and results of a multicentric study

Thymic cysts are rare, radiological diagnosis is often incidental, and cysts seldom assume clinical relevance for symptoms of compression. Thymoma were occasionally found inside both complex and simple thymic cysts. Given the challenges in accurately clinical diagnosing and since the occasionally discovering of thymoma inside both complex and simple thymic cysts, the management of thymic cysts remains controversial. Advancements in surgical tools such as robotics, applied to thymic conditions, could potentially transform the approach to thymic cysts. We report one the largest multicentric series of thymic cysts surgically treated with robotic approach, focusing on preoperative findings and surgical results. Cases were gathered from three Italian thoracic surgery centers with homogeneous clinical practice, significant experience in thymic neoplasms, and thoracic robotic skilled. Surgical intervention was indicated for patients with radiological diagnosis of thymic cysts under the following circumstances: the presence of symptoms, concurrent myasthenia gravis, cysts growing in follow-up, and the complexity of the cyst with suspicion of neoplasm. Data were collected and matched according to postoperative and pathological features to identify potential prognostic factors. Population include 57 patients, 29/28 male/female ratio with mean age of 59.46 ± 11.67 years. The average size of the thymic cysts was 29.14 ± 24.53 ranged between 3 and 150 mm. All patients undergone CT scan and mean of values of density was 25.82 ± 11-82 Hounsfield. Surgical procedures were robotic approach in all case including total/extended thymectomy 35 (61.4%) and cyst resection/partial thymectomy 22 (38.6%). There were no mortality or recurrence. Major complications rate was 5.3%. No correlations were observed between preoperative features and complication. Pathological examination revealed microfoci of thymic tumor in four cases. Robot-assisted surgery for thymic cysts showed excellent early clinical outcomes with low rate of postoperative complications also in case of large lesion. Thymic cysts should not be underestimated due to the risk of coexistent thymic neoplasm.

Distinguishing thymic cysts from low-risk thymomas via [18F]FDG PET/CT

BACKGROUND

Thymic cysts are a rare benign disease that needs to be distinguished from low-risk thymoma. [18F]fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) is a non-invasive imaging technique used in the differential diagnosis of thymic epithelial tumours, but its usefulness for thymic cysts remains unclear. Our study evaluated the utility of visual findings and quantitative parameters of [18F]FDG PET/CT for differentiating between thymic cysts and low-risk thymomas.

METHODS

Patients who underwent preoperative [18F]FDG PET/CT followed by thymectomy for a thymic mass were retrospectively analyzed. The visual [18F]FDG PET/CT findings evaluated were PET visual grade, PET central metabolic defect, and CT shape. The quantitative [18F]FDG PET/CT parameters evaluated were PET maximum standardized uptake value (SUVmax), CT diameter (cm), and CT attenuation in Hounsfield units (HU). Findings and parameters for differentiating thymic cysts from low-risk thymomas were assessed using Pearson's chi-square test, the Mann-Whitney U-test, and receiver operating characteristics (ROC) curve analysis.

RESULTS

Seventy patients (18 thymic cysts and 52 low-risk thymomas) were finally included. Visual findings of PET visual grade (P < 0.001) and PET central metabolic defect (P < 0.001) showed significant differences between thymic cysts and low-risk thymomas, but CT shape did not. Among the quantitative parameters, PET SUVmax (P < 0.001), CT diameter (P < 0.001), and CT HU (P = 0.004) showed significant differences. In ROC analysis, PET SUVmax demonstrated the highest area under the curve (AUC) of 0.996 (P < 0.001), with a cut-off of equal to or less than 2.1 having a sensitivity of 100.0% and specificity of 94.2%. The AUC of PET SUVmax was significantly larger than that of CT diameter (P = 0.009) and CT HU (P = 0.004).

CONCLUSIONS

Among the [18F]FDG PET/CT parameters examined, low FDG uptake (SUVmax ≤ 2.1, equal to or less than the mediastinum) is a strong diagnostic marker for a thymic cyst. PET visual grade and central metabolic defect are easily accessible findings.

Development and Validation of Contrast-Enhanced CT-Based Deep Transfer Learning and Combined Clinical-Radiomics Model to Discriminate Thymomas and Thymic Cysts: A Multicenter Study

RATIONALE AND OBJECTIVES

This study aims to evaluate the feasibility and effectiveness of deep transfer learning (DTL) and clinical-radiomics in differentiating thymoma from thymic cysts.

MATERIALS AND METHODS

Clinical and imaging data of 196 patients pathologically diagnosed with thymoma and thymic cysts were retrospectively collected from center 1. (training cohort: n = 137; internal validation cohort: n = 59). An independent external validation cohort comprised 68 thymoma and thymic cyst patients from center 2. Region of interest (ROI) delineation was performed on contrast-enhanced chest computed tomography (CT) images, and eight DTL models including Densenet 169, Mobilenet V2, Resnet 101, Resnet 18, Resnet 34, Resnet 50, Vgg 13, Vgg 16 were constructed. Radiomics features were extracted from the ROI on the CT images of thymoma and thymic cyst patients, and feature selection was performed using intra-observer correlation coefficient (ICC), Spearman correlation analysis, and least absolute shrinkage and selection operator (LASSO) algorithm. Univariate analysis and multivariable logistic regression (LR) were used to select clinical-radiological features. Six machine learning classifiers, including LR, support vector machine (SVM), k-nearest neighbors (KNN), Light Gradient Boosting Machine (LightGBM), Adaptive Boosting (AdaBoost), and Multilayer Perceptron (MLP), were used to construct Radiomics and Clinico-radiologic models. The selected features from the Radiomics and Clinico-radiologic models were fused to build a Combined model. Receiver operating characteristic curve (ROC), calibration curve, and decision curve analysis (DCA) were used to evaluate the discrimination, calibration, and clinical utility of the models, respectively. The Delong test was used to compare the AUC between different models. K-means clustering was used to subdivide the lesions of thymomas or thymic cysts into subregions, and traditional radiomics methods were used to extract features and compare the ability of Radiomics and DTL models to reflect intratumoral heterogeneity using correlation analysis.

RESULTS

The Densenet 169 based on DTL performed the best, with AUC of 0.933 (95% CI: 0.875-0.991) in the internal validation cohort and 0.962 (95% CI: 0.923-1.000) in the external validation cohort. The AdaBoost classifier achieved AUC of 0.965 (95% CI: 0.923-1.000) and 0.959 (95% CI: 0.919-1.000) in the internal and external validation cohorts, respectively, for the Radiomics model. The LightGBM classifier achieved AUC of 0.805 (95% CI: 0.690-0.920) and 0.839 (95% CI: 0.736-0.943) in the Clinico-radiologic model. The AUC of the Combined model in the internal and external validation cohorts was 0.933 (95% CI: 0.866-1.000) and 0.945 (95% CI: 0.897-0.994), respectively. The results of the Delong test showed that the Radiomics model, DTL model, and Combined model outperformed the Clinico-radiologic model in both internal and external validation cohorts (p-values were 0.002, 0.004, and 0.033 in the internal validation cohort, while in the external validation cohort, the p-values were 0.014, 0.006, and 0.015, respectively). But there was no statistical difference in performance among the three models (all p-values <0.05). Correlation analysis showed that radiomics performed better than DTL in quantifying intratumoral heterogeneity differences between thymoma and thymic cysts.

CONCLUSION

The developed DTL model and the Combined model based on radiomics and clinical-radiologic features achieved excellent diagnostic performance in differentiating thymic cysts from thymoma. They can serve as potential tools to assist clinical decision-making, particularly when endoscopic biopsy carries a high risk.

Computed tomography radiomic feature analysis of thymic epithelial tumors: Differentiation of thymic epithelial tumors from thymic cysts and prediction of histological subtypes

PURPOSE

To investigate the value of computed tomography (CT) radiomic feature analysis for the differential diagnosis between thymic epithelial tumors (TETs) and thymic cysts, and prediction of histological subtypes of TETs.

MATERIALS AND METHODS

Twenty-four patients with TETs (13 low-risk and 9 high-risk thymomas, and 2 thymic carcinomas) and 12 with thymic cysts were included in this study. For each lesion, the radiomic features of a volume of interest covering the lesion were extracted from non-contrast enhanced CT images. The Least Absolute Shrinkage and Selection Operator (Lasso) method was used for the feature selection. Predictive models for differentiating TETs from thymic cysts (model A), and high risk thymomas + thymic carcinomas from low risk thymomas (model B) were created from the selected features. The receiver operating characteristic curve was used to evaluate the effectiveness of radiomic feature analysis for differentiating among these tumors.

RESULTS

In model A, the selected 5 radiomic features for the model A were NGLDM_Contrast, GLCM_Correlation, GLZLM_SZLGE, DISCRETIZED_HISTO_Entropy_log2, and DISCRETIZED_HUmin. In model B, sphericity was the only selected feature. The area under the curve, sensitivity, and specificity of radiomic feature analysis were 1 (95% confidence interval [CI]: 1-1), 100%, and 100%, respectively, for differentiating TETs from thymic cysts (model A), and 0.76 (95%CI: 0.53-0.99), 64%, and 100% respectively, for differentiating high-risk thymomas + thymic carcinomas from low-risk thymomas (model B).

CONCLUSION

CT radiomic analysis could be utilized as a non-invasive imaging technique for differentiating TETs from thymic cysts, and high-risk thymomas + thymic carcinomas from low-risk thymomas.

Approach to Imaging of Mediastinal Masses

Mediastinal masses present a diagnostic challenge due to their diverse etiologies. Accurate localization and internal characteristics of the mass are the two most important factors to narrow the differential diagnosis or provide a specific diagnosis. The International Thymic Malignancy Interest Group (ITMIG) classification is the standard classification system used to localize mediastinal masses. Computed tomography (CT) and magnetic resonance imaging (MRI) are the two most commonly used imaging modalities for characterization of the mediastinal masses.

Surgical indications for mediastinal cysts-a narrative review

Background and Objective

Whether and when surgical intervention is indicated for mediastinal cysts is a matter of some debate. While most mediastinal cysts are found incidentally, the anatomic location, clinical presentation, and symptoms, as well as the potential for malignancy, are important considerations that inform decisions related to whether to intervene surgically. The objective of this review is to summarize the current literature regarding the criteria for surgical excision of mediastinal cysts and provide a framework for the clinician and surgeon to arrive at a decision regarding the appropriateness of surgical intervention of mediastinal cysts.

Methods

A review of the published literature in the last 45 years (1977-2022) was conducted through PubMed, MeSh and Google Scholar. We included retrospective reviews, meta-analyses, and case studies published in the English language. A single author identified eligible studies, and those identified were reviewed by the team until consensus was met. Pediatric literature was excluded from this review.

Key Content and Findings

The current literature predominantly contains case studies, small retrospective studies, and meta-analyses describing mediastinal cysts. In the anterior mediastinum, multiloculated thymic cysts should be resected to rule out thymic malignancy. Intralesional fat, smooth borders, and a more midline location are features suggestive of a benign process, while asymmetric cystic wall thickening has been associated with malignancy. Both esophageal and bronchogenic cysts should be excised, taking into account the risk of complications (up to a 45% risk) of infection, rupture, or compression, as well as the rare risk of associated malignancy. Simple thymic and small pericardial cysts can be observed and followed with serial radiographic tools and should be resected if they increase in size, compress surrounding structures, or lead the patient to develop symptoms.

Conclusions

Since mediastinal cysts are rare and often asymptomatic, there are no formal guidelines outlining when surgical intervention should be undertaken. Based on our review of the literature, surgical intervention should be pursued if the patient's symptoms correlate with radiographic findings of a mediastinal cyst, there is compression of the surrounding structures, and concern of malignancy is present.

Mediastinal thymic cysts: a narrative review

Background and Objective

Mediastinal thymic cysts are a relatively rare pathology. With the expansion of eligible individuals screened with cross-sectional imaging for lung cancer, it is likely that there will be an increase in the number of individuals presenting with these cysts. Understanding this rare pathology will become more important when this incidental pathology is encountered.

Methods

Search of PubMed was undertaken using keywords "mediastinal", "mediastinum", "thymic", "thymus", "cyst". Relevant literature was reviewed and selected for this comprehensive narrative review, including case reports, case series, and retrospective reviews.

Key Content and Findings

Thymic cysts in the mediastinum can be classified into two broad categories, congenital and inflammatory. Accurate diagnosis by imaging is challenging and the majority of patients are asymptomatic. Literature suggests that the majority of cysts are benign, however an unknown percentage may harbor neoplastic processes and over time can cause significant compressive symptoms. Definitive treatment and diagnosis is surgical, with overall excellent outcomes. The decision to pursue surgical treatment versus surveillance requires a shared decision making approach with patients.

Conclusions

Given the scarcity of available high quality evidence regarding the management of mediastinal thymic cysts, this review provides practitioners a broad knowledge base to guide patients to make informed decisions.

Fluorescence Imaging-Guided Identification of Thymic Masses Using Low-Dose Indocyanine Green

BACKGROUND

Indocyanine green (ICG) fluorescence imaging has been used to detect many types of tumors during surgery; however, there are few studies on thymic masses and the dose and time of ICG injection have not been optimized.

OBJECTIVE

We aimed to evaluate the optimal ICG injection dose and timing for detecting thymic masses during surgery.

METHOD

Forty-nine consecutive patients diagnosed with thymic masses on preoperative computed tomography (CT) and scheduled to undergo thymic cystectomy or thymectomy were included. Patients were administered 1, 2, or 5 mg/kg of ICG at different times. Thymic masses were observed during and after surgery using a near-infrared fluorescence imaging system, and the fluorescence signal tumor-to-normal ratio (TNR) was analyzed.

RESULTS

Among the 49 patients, 14 patients with thymic cysts showed negative fluorescence signals, 33 patients with thymoma or thymic carcinoma showed positive fluorescence signals, and 2 patients showed insufficient fluorescence signals. The diagnosis of thymic masses based on CT was correct in 32 (65%) of 49 cases; however, the differential diagnosis of thymic masses based on NIR signals was correct in 47 of 49 cases (96%), including 14 cases of thymic cysts (100%) and 33 cases of thymomas or thymic carcinomas (94%). In addition, TNR was not affected by the time or dose of ICG injection, histological type, stage, or tumor size.

CONCLUSIONS

Low-dose intravenous injection of ICG at flexible time can detect thymic tumors. In addition, thymic cysts can be distinguished from thymomas or thymic carcinomas during surgery by the absence of ICG fluorescence signals.

Rare case of a synchronous pleural solitary fibrous tumour and a thymic cyst

We present a unique case of a 41-year-old man with an anterior mediastinal mass and a pulmonary nodule, found incidentally on a thoracic CT. Further evaluation with an MRI revealed a thymic cyst which was multiloculated with several septations. Biopsy of the pulmonary nodule was performed and histology was consistent with a solitary fibrous tumour (SFT), on the benign spectrum. Both lesions were successfully resected simultaneously via a median sternotomy approach. Final full histological diagnoses confirmed a multiloculated thymic cyst and a completely excised SFT.

Special Computed Tomography Imaging Features of Thymic Cyst

OBJECTIVE

To explore the features and diagnostic value of computed tomography (CT) imaging in cases of thymic cysts.

METHODS

A total of 24 cases of the thymic cysts (confirmed by postoperative pathology) were retrospectively analyzed. The location, morphology, and density of the thymic cysts were summarized, and the changes in CT value of the region of interest (ROI) in the thymic cysts between noncontrast enhanced and enhanced chest scans were compared and classified.

RESULTS

The average long-axis dimension was 17.50 ± 6.00 mm, the CT value range across the 24 cases was 5-81 HU, and the average CT value of the noncontrast enhanced scans was 39.75 ± 20.66 HU. The CT value in the noncontrast enhanced scan was >20 HU in 79% of the sample cases. The CT value in the ROI of the thymic cysts under enhanced scan showed a significant decrease in 15 cases, a significant increase in 5 cases, and an insignificant change in 4 cases.

CONCLUSION

The CT values of the thymic cysts in the enhanced scans were generally lower than in the noncontrast enhanced scans, which might be a valuable finding for thymic cysts diagnosis.

CT-Based Radiomics Nomogram for Differentiation of Anterior Mediastinal Thymic Cyst From Thymic Epithelial Tumor

Objectives

This study aimed to distinguish preoperatively anterior mediastinal thymic cysts from thymic epithelial tumors via a computed tomography (CT)-based radiomics nomogram.

Methods

This study analyzed 74 samples of thymic cysts and 116 samples of thymic epithelial tumors as confirmed by pathology examination that were collected from January 2014 to December 2020. Among the patients, 151 cases (scanned at CT 1) were selected as the training cohort, and 39 cases (scanned at CT 2 and 3) served as the validation cohort. Radiomics features were extracted from pre-contrast CT images. Key features were selected by SelectKBest and least absolute shrinkage and selection operator and then used to build a radiomics signature (Rad-score). The radiomics nomogram developed herein via multivariate logistic regression analysis incorporated clinical factors, conventional CT findings, and Rad-score. Its performance in distinguishing the samples of thymic cysts from those of thymic epithelial tumors was assessed via discrimination, calibration curve, and decision curve analysis (DCA).

Results

The radiomics nomogram, which incorporated 16 radiomics features and 3 conventional CT findings, including lesion edge, lobulation, and CT value, performed better than Rad-score, conventional CT model, and the clinical judgment by radiologists in distinguishing thymic cysts from thymic epithelial tumors. The area under the receiver operating characteristic (ROC) curve of the nomogram was 0.980 [95% confidence interval (CI), 0.963–0.993] in the training cohort and 0.992 (95% CI, 0.969–1.000) in the validation cohort. The calibration curve and the results of DCA indicated that the nomogram has good consistency and valuable clinical utility.

Conclusion

The CT-based radiomics nomogram presented herein may serve as an effective and convenient tool for differentiating thymic cysts from thymic epithelial tumors. Thus, it may aid in clinical decision-making.

Role of quantitative energy spectrum CT parameters in differentiating thymic epithelial tumours and thymic cysts

AIM

To explore the utility of multiple energy spectrum computed tomography (CT) parameters in distinguishing thymic epithelial tumours (TETs) from thymic cysts among lesions <5 cm in diameter.

MATERIALS AND METHODS

Data pertaining to 56 patients with TETs and thymic cysts <5 cm in diameter were assessed retrospectively. All patients underwent surgical resection and the diagnosis was confirmed histopathologically. Thirty-five patients with TETs (average age, 51.97 years) and 21 patients with thymic cysts (average age, 50.54 years) were included. The region of interest for the lesion on the energy spectrum CT was delineated on the post-processing workstation, and multiple parameters of the energy spectrum CT were obtained. The diagnostic efficacies of the parameters were analysed using receiver operating characteristic (ROC) curves.

RESULTS

To distinguish small TETs from thymic cysts, a single-energy CT value of 60 keV showed good differential diagnostic performance in the arterial phase (cut-off value = 68.42 HU; area under the curve [AUC] = 0.978), a single-energy CT value of 70 keV showed good differential diagnostic performance in the venous phase (cut-off value = 59.77 HU; AUC = 0.956). In the arterial and venous phases, effective atomic numbers of 8.065 and 8.175, respectively, were used as cut-off values to distinguish small TETs from thymic cysts (AUC = 0.972 and AUC = 0.961, respectively). Iodine concentrations of 10.99 and 11.05 were used as cut-off values to distinguish small TETs from thymic cysts (AUC = 0.956 and AUC = 0.924, respectively).

CONCLUSION

According to the present study, energy spectrum CT parameters may have clinical value in the differential diagnosis of TETs and thymic cysts.

Thymic masses and mimics in adults: review of common and uncommon pathologies

The thymus is a primary lymphoid organ that plays a key role in the immune system development. Normally, it is located in the anterior mediastinum and it changes tissue composition with progressive fatty involution with age. The spectrum of pathological processes involving the thymus include enlargement, tumour development, and cystic change. In addition, other local pathology can mimic thymic disease. Differentiating these entities can be challenging; however, recognizing key features on imaging is essential to appropriately guide further investigation and therapy. The focus of this pictorial review will be to highlight the important distinguishing features of thymic hyperplasia, thymomas, thymic cysts, thymic neuroendocrine tumours (NETs), thymolipomas, mediastinal teratomas, and other mimics of thymic disease. Knowledge of the varying imaging findings on computed tomography and magnetic resonance imaging is valuable for radiologists to appropriately classify disease, avoid misdiagnosis, and expedite therapy.

Imaging of the Anterior/Prevascular Mediastinum

Prevascular mediastinal masses include a wide range of benign and malignant entities. Localization of mediastinal masses to specific compartments together with characteristic imaging findings and demographic and clinical information allows formulation of a focused differential diagnosis. Radiologists may use these methods to distinguish between surgical and nonsurgical cases and thus inform patient management and have an impact on outcomes. Treatment of choice varies based on the pathology, ranging from no intervention or serial imaging follow-up to surgical excision, chemotherapy, and/or radiation.

Multilocular Thymic Cyst in a Young, Otherwise Healthy Woman: A Case Report

Thymic cysts are rare lesions, accounting approximately for 1% of all mediastinal masses. We report a case of a 36-year old woman who presented preoperatively with a calcified mass shadow found on a routine chest radiograph X-ray. After further investigation with chest computed tomography (CT), magnetic resonance imaging (MRI), and tests for Myasthenia gravis, a benign mediastinal cyst was diagnosed and the patient underwent median sternotomy and complete surgical excision of the lesion. The histological examination described a multilocular thymic cyst. Thymic cysts are usually associated with thymic epithelial tumors, such as thymomas, or multisystemic morbid conditions such as human immunodeficiency virus (HIV) infection, rheumatologic disease, and Myasthenia gravis. At all follow-up examinations to date, the patient remains healthy.

Clinical characteristics and management of primary mediastinal cysts: A single-center experience

Background

In this study we aimed to assess the clinical outcomes of performing video‐assisted thoracic surgery (VATS) to treat primary mediastinal cysts (PMCs) and investigate the clinical factors which increase the difficulties associated with VATS.

Methods

The medical records of all consecutive PMC patients, who underwent surgical resection from April 2001 to July 2016, were reviewed and 282 patients were included. Clinical characteristics, imaging features, and surgical outcomes were analyzed. Follow‐up data were successfully obtained from 230 PMC patients by telephone or outpatient clinic annually. The latest follow‐up was July 2019.

Results

VATS was performed in 278 patients and four patients were converted into thoracotomy. The mean operation time and intraoperative bleeding were 102.4 ± 40.9 minutes (range 25–360 minutes) and 52.4 ± 75.1 mL (range 5–600 mL), respectively. The intra‐ and postoperative complication rates were 2.8 and 5.7%, respectively. Seven patients with bronchogenic cysts showed severe cyst adhesion to vital mediastinal structures and thus had incomplete resection. Multivariable logistic analysis revealed that a maximal cyst diameter greater than 5 cm was significantly associated with increased risks of operation time extension (OR = 2.106; 95% CI: 1.147–3.865, P = 0.016) and intraoperative blood loss increase (OR = 4.428; 95% CI: 1.243–16.489, P = 0.022). A total of 230 patients had follow‐up data. The median follow‐up time was 70 months (range, 36–210 months). No local recurrence was observed.

Conclusions

Surgical resection by VATS may be recommended for PMC management as a primary therapeutic strategy. Cysts with a maximum diameter greater than 5 cm or cysts adjacent to vital mediastinal structures can increase the surgical difficulties.

Key points

• Significant findings of the study

A diameter >5 cm and adhesions significantly increased the risk of operation time extension together with increased blood loss.

• What this study adds

Cysts with a diameter >5 cm or those adjacent to vital mediastinal structures increased the potential for surgical difficulties.

Clinical Experience with Thymic Cystectomy: A Single-Institution Study of 117 Cases from 2013 to 2019

Background

The aim of this study was to summarize the clinical experience of thymic cysts treatment from a single center.

Material/Methods

Clinical data, imaging, pathological results, and follow-up results of thymic cyst patients who underwent surgery from January 2013 to September 2019 were retrospectively reviewed.

Results

A total of 117 patients were enrolled, including 76 asymptomatic patients and 41 symptomatic patients. The average diameter of thymic cysts, the cysts in asymptomatic patients, and those in symptomatic patients were 31.93±19.92 mm, 29.28±17.97 mm, and 36.85±22.50 mm, respectively. The number of cysts ranged from 1 to 3 cm, 3 to 6 cm, and >6 cm in 73 cases (62.4%), 32 cases (27.3%), and 12 cases (10.3%), respectively. There was no correlation between the size of thymic cysts and the presence or absence of symptoms. Only 20 cases (17.1%) were correctly diagnosed as thymic cysts before surgery. There were 67 patients (57.3%) who underwent video-assisted thoracic surgery (VATS) and 50 cases (42.7%) underwent open surgery. Cystectomy was performed in 93 cases (79.5%) and 24 cases (20.5%) underwent simultaneous resection of thymic cysts and other thoracic tumors. Compared with the thoracotomy group, the VATS group had shorter hospital stay and chest tube indwelling time. No serious complications occurred after surgery. The median follow-up time was 45.0 months (range 4.0–84.0 months) and there was no recurrence.

Conclusions

Attention should be paid to the accuracy of preoperative diagnosis of thymic cysts and the reduction of asymptomatic thymic cystectomy. For patients who have both thymic cysts and other thoracic tumors, simultaneous surgery is safe and feasible.

Differentiating thymoma from thymic cyst in anterior mediastinal abnormalities smaller than 3 cm

Background

Computed tomography (CT) screening for lung cancer has led to frequent findings of small anterior mediastinal masses. It is very hard to distinguish small thymomas from thymic cysts. The objective of this study was to develop a clinical model for predicting small thymomas (<3 cm) in asymptomatic patients.

Methods

Patients who underwent thymectomy for anterior mediastinal masses between 2004 and 2016 were included. All preoperative CT scans (pre- and post-enhanced) were retrospectively reviewed. Size, location, contour, shape, presence of calcification, and enhancement [Hounsfield units (HU)] were evaluated. A nomogram was built based on the predictive factors. For external validation, patients undergoing thymectomy in 2017 were enrolled and thymoma prediction was computed using the proposed nomogram.

Results

The study population consisted of 43 patients with thymoma and 57 with thymic cyst. The multivariable analysis identified a lobulated contour and a large difference in HU between post- and pre-enhancement as predictive factors of thymoma. These factors were included in the nomogram, which showed 95% (19/20) power for predicting thymoma after external validation.

Conclusions

This clinical model can be used to predict thymoma in patients with small, asymptomatic thymic abnormalities on CT screening.

Distinguishing between Thymic Epithelial Tumors and Benign Cysts via Computed Tomography

Objective

To investigate whether computed tomography (CT) and fluorine-18-labeled fluoro-2-deoxy-D-glucose (FDG) positron emission tomography (PET) may be applied to distinguish thymic epithelial tumors (TETs) from benign cysts in the anterior mediastinum.

Materials and Methods

We included 262 consecutive patients with pathologically proven TETs and benign cysts 5 cm or smaller who underwent preoperative CT scans. In addition to conventional morphological and ancillary CT findings, the relationship between the lesion and the adjacent mediastinal pleura was evaluated qualitatively and quantitatively. Mean lesion attenuation was measured on CT images. The maximum standardized uptake value (SUVmax) was obtained with FDG-PET scans in 40 patients. CT predictors for TETs were identified with multivariate logistic regression analysis. For validation, we assessed the diagnostic accuracy and inter-observer agreement between four radiologists in a size-matched set of 24 cysts and 24 TETs using a receiver operating characteristic curve before and after being informed of the study findings.

Results

The multivariate analysis showed that post-contrast attenuation of 60 Hounsfield unit or higher (odds ratio [OR], 12.734; 95% confidence interval [CI], 2.506–64.705; p = 0.002) and the presence of protrusion from the mediastinal pleura (OR, 9.855; 95% CI, 1.749–55.535; p = 0.009) were the strongest CT predictors for TETs. SUVmax was significantly higher in TETs than in cysts (5.3 ± 2.4 vs. 1.1 ± 0.3; p < 0.001). After being informed of the study findings, the readers' area under the curve improved from 0.872–0.955 to 0.949–0.999 (p = 0.066–0.149). Inter-observer kappa values for protrusion were 0.630–0.941.

Conclusion

Post-contrast CT attenuation, protrusion from the mediastinal pleura, and SUVmax were useful imaging features for distinguishing TETs from cysts in the anterior mediastinum.

Congenital Thymic Cyst: Antenatal Diagnosis and Postnatal Management

Thymic cyst is regarded as a rare anomaly, accounting for about 3% of all anterior mediastinal masses. It can be either congenital or acquired. Congenital thymic cysts are usually asymptomatic, with about 50% found incidentally in childhood or adolescence. We report a case of 1-month 23-day-old male baby who was antenatally diagnosed at 32 weeks' gestation. Spontaneous resolution did not take place in the antenatal or neonatal period; instead, there was an increase in size on follow-up imaging. The baby was successfully managed by surgical excision.

Is single-port video-assisted thoracic surgery for mediastinal cystectomy feasible?

Background

Video-assisted thoracic surgery (VATS) for mediastinal cysts has been used with increasing frequency. Both single-port VATS and three-port VATS procedures are used for mediastinal cystectomy. Few studies have been published to compare three-port VATS and single-port VATS procedures in mediastinal cystectomy.

Methods

Forty-five patients with mediastinal cysts who underwent single-port procedures (n = 23) or three-port procedures (n = 22) in our department from January 2016 to July 2018 were retrospectively analysed. The perioperative conditions and pathological findings were analysed.

Results

The single-port group showed shorter operation times [45 (35–60) vs 55 (45–80) min, p = 0.013], less retention time of the thoracic drainage tube [27(24–48) vs 48(48–70) p < 0.001)], shorter postoperative hospital stays [5(4–6) vs 7(5–7), p = 0.011] and less costs [2.0)1.2–2.5) vs 2.5(1.9–3.5), p = 0.032] than those of the three-port group. No difference was found in case conversions to open procedures (p > 0.99) or second operations (p > 0.99). Logistic regression analysis showed that the surgical method (p = 0.426) and surgeon experience (p = 0.719) were not independent prognostic factors for the success of surgery.

Conclusions

The single-port VATS procedure was not inferior to the three-port VATS procedure for mediastinal cystectomy. The single-port VATS procedure is a feasible choice for mediastinal cystectomy.