Magnetic Resonance Elastography of Anterior Mediastinal Tumors.

BACKGROUND: Preoperative differentiation of the types of mediastinal tumors is essential. Magnetic resonance (MR) elastography potentially provides a noninvasive method to assess the classification of mediastinal tumor subtypes. PURPOSE: To evaluate the use of MR elastography in anterior mediastinal masses and to characterize the mechanical properties of tumors of different subtypes. STUDY TYPE: Prospective. SUBJECTS: 189 patients with anterior mediastinal tumors (AMTs) confirmed by histopathology (62 thymomas, 53 thymic carcinomas, 57 lymphomas, and 17 germ cell tumors). FIELD STRENGTH/SEQUENCE: A gradient echo-based 2D MR elastography sequence and a diffusion-weighted imaging (DWI) sequence at 3.0 T. ASSESSMENT: Stiffness and apparent diffusion coefficients (ADC) were measured in AMTs using MR elastography-derived elastograms and DWI-derived ADC maps, respectively. The aim of this study is to identify whether MR elastography can differentiate between the histological subtypes of ATMs. STATISTICAL TESTS: One-way analysis of variance (ANOVA), two-way ANOVA, Pearson's linear correlation coefficient (r), receiver operating characteristic (ROC) curve analysis; P < 0.05 was considered significant. RESULTS: Lymphomas had significantly lower stiffness than other AMTs (4.0 ± 0.63 kPa vs. 4.8 ± 1.39 kPa). The mean stiffness of thymic carcinomas was significantly higher than that of other AMTs (5.6 ± 1.41 kPa vs. 4.2 ± 0.94 kPa). Using a cutoff value of 5.0 kPa, ROC analysis showed that lymphomas could be differentiated from other AMTs with an accuracy of 59%, sensitivity of 97%, and specificity of 38%. Using a cutoff value of 5.1 kPa, thymic carcinomas could be differentiated from other AMTs with an accuracy of 84%, sensitivity of 67%, and specificity of 90%. However, there was an overlap in the stiffness values of individual thymomas (4.2 ± 0.71; 3.9-4.5), thymic carcinomas (5.6 ± 1.41; 5.0-6.1), lymphomas (4.0 ± 0.63; 3.8-4.2), and germ cell tumors (4.5 ± 1.79; 3.3-5.6). DATA CONCLUSION: MR elastography-derived stiffness may be used to evaluate AMTs of various histologies. TECHNICAL EFFICACY: Stage 2.

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.

A rare case of tumor-to-tumor metastasis from thymic carcinoma to an ovarian mature teratoma.

Metastasis from one neoplasm to another is referred to as tumor-to-tumor metastasis (TTM). TTM is rarely observed. Here, we present a patient with TTM from a thymic carcinoma to an ovarian mature teratoma. A 25-year-old woman, diagnosed with unresectable thymic carcinoma, presented with a cyst with a solid tumor component in her right ovary. Laparoscopic cystectomy of the right ovary revealed that the solid tumor was a distant metastasis of the thymic carcinoma in an ovarian mature teratoma. The possibility of malignant transformation of the ovarian mature teratoma was ruled out, enabling accurate staging of the thymic carcinoma. This case emphasizes the need for clinicians to consider TTM and the importance of pathological confirmation of TTM when investigating potential distant metastases.

An intrapulmonary tumor out of the box / Un tumor intrapulmonar “out of the box”

Primary intrapulmonary thymomas (PIT) are very rare tumors of unclear pathogenesis. We report a case of a 60-years-old woman who present with an accidental finding of a mass on her chest. Histology analysis shown to be primary intrapulmonary thymoma and she underwent surgical resection, remaining currently asymptomatic and without evidence of recurrence or metastasis. Since its rarity, reporting these cases is essential to better understand its clinical course and management. (AU)

Los timomas intrapulmonares primarios (TIP) son tumores muy infrecuentes de patogenia incierta. Presentamos el caso de una mujer de 60 años que presenta el hallazgo accidental de una masa en el tórax. El análisis histológico demostró que se trataba de un timoma intrapulmonar primario y fue sometida a resección quirúrgica, permaneciendoactualmente asintomática y sin evidencia de recurrencia o metástasis. Dada su rareza, la comunicación de estos casos es esencial para comprender mejor su curso clínico y manejo. (AU)

Clinical Outcomes of Thymic Carcinoma: The Role of Radiotherapy Combined with Multimodal Treatments.

INTRODUCTION: We aimed to identify the role of radiotherapy (RT) in the treatment of thymic carcinoma as well as the optimal RT target volume. MATERIALS AND METHODS: This single-institution retrospective study included 116 patients diagnosed with thymic carcinoma between November 2006 and December 2021 who received multimodal treatment including RT with or without surgery or chemotherapy. Seventy-nine patients (68.1%) were treated with postoperative RT, 17 patients (14.7%) with preoperative RT, 11 patients (9.5%) with definitive RT, and nine patients (7.8%) with palliative RT. The target volume was defined as the tumor bed or gross tumor with margin, and selective irradiation of the regional nodal area was performed when involved. RESULTS: With a median follow-up of 37.0 (range, 6.7-174.3) months, the 5-year overall survival (OS), progression-free survival, and local recurrence-free survival rates were 75.2%, 47.7% and 94.7%, respectively. The 5-year OS was 51.9% in patients with unresectable disease. Overall, 53 recurrences were observed, of which distant metastasis was the most common pattern of failure (n = 32, 60.4%) after RT. No isolated infield or marginal failures were observed. Thirty patients (25.8%) who had lymph node metastases at the initial diagnosis had regional nodal areas irradiated. There was no lymph node failure inside the RT field. A tumor dimension of ≥5.7 cm (hazard ratio [HR] 3.01; 95% confidence interval [CI] 1.25-7.26; p = 0.030) and postoperative RT (HR 0.20; 95% CI 0.08-0.52; p = 0.001) were independently associated with OS. Intensity-modulated-RT-treated patients developed less overall toxicity (p < 0.001) and esophagitis (p < 0.021) than three-dimensional-conformal-RT-treated patients. CONCLUSIONS: A high local control rate was achieved with RT in the primary tumor sites and involved lymph node area in the treatment of thymic carcinoma. A target volume confined to the tumor bed or gross tumor plus margin with the involved lymph node stations seems reasonable. The advanced RT techniques with intensity-modulated RT have led to reduced RT-related toxicity.

Mucosa-associated lymphoid tissue lymphoma in thymus: a SEER analysis.

OBJECTIVES: The present study explores an extremely rare disease, thymic mucosa-associated lymphoid tissue (MALT) lymphoma, for its characteristics and prognostic factors by analyzing the Surveillance, Epidemiology, and End Results (SEER) database. METHODS: From 2000 to 2018, cases with a diagnosed thymic MALT lymphoma were extracted. Clinical characteristics, treatments, and survival patterns of these cases were analyzed. RESULTS: Thymic MALT lymphoma (n = 26) accounted for 0.09% of all MALT lymphomas. With a sex ratio of 0.53 (male/female), 68% white population was affected. Most cases were diagnosed with Ann Arbor stage I (50%), yet advanced-stage did not show worse prognosis (p = 0.236). Different treatment protocols did not influence the overall prognosis (p > 0.99). The 5- and 10- year overall survival rates were 83.1% and 78.2%, respectively. Older than 70 years may be an independent risk factor for overall survival (HR = 7.166 [95% CI 1.173-43.756], p = 0.033). CONCLUSION: Thymic MALT lymphoma is a highly rare disease with a favorable prognosis. Ann Arbor staging might not be appropriate to classify severity of this disease or its treatment. Older people may have worse survival. A standardized treatment mode needs to be established, and surgery could remain as the mainstay.

Mediastinal thymoma in a patient with previous rectal and breast cancers: A report of a case with multiple primary cancers and review of literature.

A 42-year-old female patient with intellectual disability was presented to us as a newly diagnosed case of thymoma. She was identified as a case of multiple primary cancers, including adenocarcinoma of the rectum, carcinoma of the breast, and mediastinal thymoma, in a 15-year period, who underwent chemotherapy, radiotherapy, and surgical resection.

Ectopic thymic carcinoma of the parotid gland.

Ectopic thymic carcinoma (ETC) of the parotid gland is a rare entity. This report describes the case of a 52-year-old man with a painless mass in the right parotid gland. Magnetic resonance imaging (MRI) showed a biphasic mass consisting of a central segment and a peripheral segment. The patient underwent a superficial parotidectomy, and point-to-point correspondence sampling for analysis based on MRI findings was performed. The pathological finding was ETC, and there was an excellent association between MRI characteristics and histopathological findings. Subsequently, the patient underwent postoperative radiation therapy. At the 9-month follow-up, he had recovered well without facial paralysis, and there was no evidence of recurrence or metastasis. This report describes the clinical, radiological, and pathological features of the ETC.

Diagnostic and prognostic values of 2-[18F]FDG PET/CT in resectable thymic epithelial tumour.

OBJECTIVES: We aimed to evaluate the diagnostic ability for the prediction of histologic grades and prognostic values on recurrence and death of pretreatment 2-[18F]FDG PET/CT in patients with resectable thymic epithelial tumours (TETs). METHODS: One hundred and fourteen patients with TETs who underwent pretreatment 2-[18F]FDG PET/CT between 2012 and 2018 were retrospectively evaluated. TETs were classified into three histologic subtypes: low-risk thymoma (LRT, WHO classification A/AB/B1), high-risk thymoma (HRT, B2/B3), and thymic carcinoma (TC). Area under the receiver operating characteristics curve (AUC) was used to assess the diagnostic performance of PET/CT variables (maximum standardised uptake value [SUVmax], metabolic tumour volume [MTV], total lesion glycolysis [TLG], maximum diameter). Cox proportional hazards models were built using PET/CT and clinical variables. RESULTS: The tumours included 52 LRT, 33 HRT, and 29 TC. SUVmax showed good diagnostic ability for differentiating HRT/TC from LRT (AUC 0.84, 95% confidence interval [CI] 0.76 - 0.92) and excellent ability for differentiating TC from LRT/HRT (AUC 0.94, 95% CI 0.90 - 0.98), with significantly higher values than MTV, TLG, and maximum diameter. With an optimal cut-off value of 6.4, the sensitivity, specificity, and accuracy for differentiating TC from LRT/HRT were 69%, 96%, and 89%, respectively. In the multivariable Cox proportional hazards analyses for freedom-from-recurrence, SUVmax was an independent prognostic factor (p < 0.001), whereas MTV and TLG were not. SUVmax was a significant predictor for overall survival in conjunction with clinical stage and resection margin. CONCLUSION: SUVmax showed excellent diagnostic performance for prediction of TC and significant prognostic value in terms of recurrence and survival. KEY POINTS: • Maximum standardised uptake value (SUVmax) shows excellent performance in the differentiation of thymic carcinoma from low- and high-risk thymoma. • SUVmax is an independent prognostic factor for freedom-from-recurrence in the multivariable Cox proportional hazard model and a significant predictor for overall survival. • 2-[18F]FDG PET/CT can provide a useful diagnostic and prognostic imaging biomarker in conjunction with histologic classification and stage and help choose appropriate management for thymic epithelial tumours.

Differentiating thymoma, thymic carcinoma and lymphoma based on collagen fibre patterns with T2- and diffusion-weighted magnetic resonance imaging.

OBJECTIVES: The amount and distribution of intratumoural collagen fibre vary among different thymic tumours, which can be clearly detected with T2- and diffusion-weighted MR images. To explore the incidences of collagen fibre patterns (CFPs) among thymomas, thymic carcinomas and lymphomas on imaging, and to evaluate the efficacy and reproducibility of CFPs in differential diagnosis of thymic tumours. MATERIALS AND METHODS: Three hundred and ninety-eight patients with pathologically diagnosed thymoma, thymic carcinoma and lymphoma who underwent T2- and diffusion-weighted MR imaging were retrospectively enrolled. CFPs were classified into four categories: septum sign, patchy pattern, mixed pattern and no septum sign. The incidences of CFPs were compared among different thymic tumours, and the efficacy and reproducibility in differentiating the defined tumour types were analysed. RESULTS: There were significant differences in CFPs among thymomas, thymic squamous cell carcinomas (TSCCs), other thymic carcinomas and neuroendocrine tumours (OTC&NTs) and thymic lymphomas. Septum signs were found in 209 (86%) thymomas, which differed between thymomas and any other thymic neoplasms (all p < 0.005). The patchy, mixed patterns and no septum sign were mainly seen in TSCCs (80.3%), OTC&NTs (78.9%) and thymic lymphomas (56.9%), respectively. The consistency of different CFP evaluation between two readers was either good or excellent. CFPs achieved high efficacy in identifying the thymic tumours. CONCLUSION: The CFPs based on T2- and diffusion-weighted MR imaging were of great value in the differential diagnosis of thymic tumours. KEY POINTS: • Significant differences are found in intratumoural collagen fibre patterns among thymomas, thymic squamous cell carcinomas, other thymic carcinomas and neuroendocrine tumours and thymic lymphomas. • The septum sign, patchy pattern, mixed pattern and no septum sign are mainly seen in thymomas (86%), thymic squamous cell carcinomas (80.3%), other thymic carcinomas and neuroendocrine tumours (79%) and thymic lymphomas (57%), respectively. • The collagen fibre patterns have high efficacy and reproducibility in differentiating thymomas, thymic squamous cell carcinomas and thymic lymphomas.

A giant tumor of the mediastinum mixed with thymocytes and adipocytes: a case report.

A 17-year-old male was hospitalized for 6 months with chest tightness and shortness of breath. Chest CT showed large mixed density shadow of anterior mediastinum, multiple flaky fat density shadow, left lower lung compression, atelectasis, partial compression of right lung and obvious heart pressure. The patient's symptoms are caused by the compression of the heart and lung by the mediastinal mass. The results of routine examination were normal. After excluding surgical contraindications, the patient underwent resection of a huge mediastinal tumor before median thoracotomy. The operation was smooth and the intraoperative vital signs were stable. The symptoms of chest tightness and shortness of breath disappeared after operation. The size of the tumor tissue removed after operation was about 45×30×25 cm3 and the weight was about 3.7 kg. The pathological diagnosis was thymolipoma. Postoperative reexamination of chest CT showed that the heart and lungs returned to the normal position. In this case, the operation is effective for large thymic tumors, and the symptoms of the patients are significantly relieved. Early diagnosis and surgical treatment are the key to improve the prognosis of patients. In this study, we reported a successful removal of a giant thymolipoma with complete disappearance of symptoms and no serious complications such as myasthenia gravis, aplastic anemia, and vitamin B12 deficiency.

Video-Assisted Thoracic Surgery Thymectomy: Transpleural Approach.

There are several types of minimally invasive approaches for thymectomy, of which the transpleural approach by video-assisted thoracoscopic surgery is particularly useful. In this approach, thymectomy is performed from either side of the thoracic cage. Thoracic surgeons should be familiar with the principles of the procedure, the anatomy of the region, and surgical strategies for successful thymectomy. The details of transpleural thymectomy are discussed herein.

Carcinoide atípico de timo en varón de 39 años: Reporte de caso / Atypical carcinoid of thymus in a 39-year-old-man: A case report

RESUMEN El carcinoide atípico (CA) de timo es la neoplasia más agresiva y rara que surge en el mediastino anterior y que pertenece a los tumores primarios neuroendocrinos de timo. La mayoría de los pacientes son asintomáticos y según la extensión de la enfermedad pueden presentar desde tos, disnea, dolor torácico hasta síndrome de vena cava superior. Esta presentación clínica inespecífica disminuye la probabilidad del diagnóstico temprano que, sumado con el estadio avanzado al debut y la imposibilidad de resección quirúrgica reduce la tasa de supervivencia. El objetivo es dar a conocer la presentación clínica, imagenológica y patológica en un varón de 39 años con CA de timo cuyo diagnóstico definitivo se basó en el estudio histopatológico (morfología carcinoide, mitosis 0-1/2 mm2, necrosis, Ki 67 = 12%) y marcadores inmunofenotípicos del tumor (CD 56 (+), Panqueratina (+), Sinaptofisina (+), TTF -1 (-)).

ABSTRACT The atypical carcinoid (AC) of thymus is the most aggressive and uncommon neoplasm in the anterior mediastinum, that belongs to the neuroendocrine primary tumors of thymus. Most patients are asymptomatic and according to the disease extension they may present with cough, dyspnea, chest pain, and superior cava vein syndrome. This non-specific clinical presentation reduces the likelihood for making an early diagnosis; and this, together with disease stage and lack of surgical resection reduces the survival rate. The aim of this paper is to describe the clinical presentation in a 39-year old male with thymus carcinoid whose diagnosis was based on histopathological studies (carcinoid morphology, 0-1/2 mitoses/mm2), necrosis, Ki67, 12%), and immunophenotypic tumor markers (CD56(+), Pankeratin (+), Synaptophysin (+), and TTF-1 (-)).

Congenital thymoma.

Thymomas are a heterogeneous group of tumors arising from the epithelium of the thymus. They are categorized by the proportion of neoplastic epithelia to lymphocytes and by the degree of cytologic atypia. Thymomas constitute 0.2-1.5% of all malignancies and nearly all occur in patients over 20 years. We reviewed the available literature and found less than 50 cases of thymoma reported in children (<18 years of age), the youngest being 4 years old, and no cases in newborns. They represent less than 1% of all mediastinal tumors in children. Due to the limited number of cases in the pediatric population, the diagnosis and treatment in this population is extremely challenging. Thymomas in all age groups may be associated with paraneoplastic syndromes, being myasthenia gravis the most common, which is associated with a worse prognosis in the pediatric population. We present the first case of a newborn infant with congenital thymoma. This case demonstrates a rare tumor in an unusual age group and emphasizes the importance of multidisciplinary teamwork in the decision-making and management of this condition.

Thymolipoma and its Association with Myasthenia Gravis: a Multi-center Experience.

BACKGROUND: Thymolipoma is a rare benign thymic tumor that arises in the anterior mediastinum. It presents with non-specific symptoms such as chest pain and dyspnea due to compression of the tumor on surrounding structures. In addition, this tumor is associated with paraneoplastic syndromes, including myasthenia gravis. Such a relationship is still not understood and requires investigation. OBJECTIVE: Investigate the significance of myasthenia gravis in thymolipoma patients. METHODS: We present a series of 16 thymolipoma cases from multiple medical centers. Data extraction included demographic, diagnostic, radiological and laboratory, and clinical outcome variables. We also used the modified Osserman score to assess the severity of myasthenia gravis. RESULTS: Ten patients were males, and six were females; the sample mean age was 39.9 years (SD = 16.7). Upon presentation, 7/16 patients were asymptomatic, 4/16 patients had chest pain, and 2/16 had dyspnea. Seven patients were having myasthenia gravis; they experience generalized weakness (3/7), diplopia (2/7), ptosis (1/7), and bulbar weakness (1/7). Serum acetylcholine receptor antibody (AChRAb) was positive in 4 patients. All patients underwent thymectomy either via sternotomy or thoracotomy. After proper follow-up, only 2/7 of myasthenic patients had a complete remission of symptoms, no tumor recurrence was observed. CONCLUSION: Although the effect of using steroids in myasthenic patients on thymolipomic transformation still needs confirmation, diagnosis of thymolipoma should be kept in mind in myasthenic patients presenting with relevant symptoms and taking steroids. Furthermore, complete remission of myasthenic symptoms after removal of thymolipoma needs further investigation.

Congenital thymoma

Thymomas are a heterogeneous group of tumors arising from the epithelium of the thymus. They are categorized by the proportion of neoplastic epithelia to lymphocytes and by the degree of cytologic atypia. Thymomas constitute 0.2-1.5% of all malignancies and nearly all occur in patients over 20 years. We reviewed the available literature and found less than 50 cases of thymoma reported in children (<18 years of age), the youngest being 4 years old, and no cases in newborns. They represent less than 1% of all mediastinal tumors in children. Due to the limited number of cases in the pediatric population, the diagnosis and treatment in this population is extremely challenging. Thymomas in all age groups may be associated with paraneoplastic syndromes, being myasthenia gravis the most common, which is associated with a worse prognosis in the pediatric population. We present the first case of a newborn infant with congenital thymoma. This case demonstrates a rare tumor in an unusual age group and emphasizes the importance of multidisciplinary teamwork in the decision-making and management of this condition.

Enbloc resection of the largest thymic liposarcoma: A case report with literature review.

Liposarcoma is the most common soft tissue tumor which is commonly found in the retroperitoneal region. This kind of tumor is usually well-differentiated with low to no potential to metastasize. Thymoliposarcomas are extremely rare tumors that are difficult to diagnose and differentiate from thymomas and other benign conditions. Presentation of a case:This report presents a case of a 46-year-old male patient with dyspnea, generalized fatigue and non-specific chest pain caused by a giant anterior mediastinal mass. Computed tomography scan revealed a large mass in the anterior mediastinum. CT guided biopsy was consistent with thymolipoma. The tumor was surgically resected. The histological analysis of the tumor revealed thymoliposarcoma. Discussion:Thymoliposarcoma usually presents with non-specific symptoms. The mean age of the diagnosis is 55.8 years old with a slight predominance in males. The corner stone of the treatment remains surgical excision of the tumor while the role of adjuvant therapy is not well documented.

Incidental mediastinal masses detected at low-dose CT screening: prevalence and radiological characteristics.

PURPOSE: The primary and secondary aims were to investigate the prevalence of incidental mediastinal masses on low-dose chest CT examinations during health check-ups, and to review the radiological characteristics of prevascular mediastinal masses, respectively. MATERIALS AND METHODS: This retrospective study included 38,861 participants (mean age: 57.1 years; range: 21-99 years; men: 51.3%; never-smokers: 57.4%) who underwent low-dose chest CT examinations between January 2011 and December 2016. All images with incidental mediastinal masses were reviewed, and prevascular mediastinal masses were assessed for qualitative and quantitative imaging characteristics by two radiologists. Univariate and multivariate analyses were performed in clinical and CT features between some combinations of participants. RESULTS: Overall, 653 participants (1.68%, 653 of 38,861) had incidental mediastinal masses; 578 in prevascular mediastinum, including 93 intrathymic cysts and 24 thymic epithelial tumors. Presence of mediastinal mass was not significantly associated with sex (p = 0.089) and smoking history (p = 0.098) but with age (p < 0.001). Significant differences were found between intrathymic cysts and thymic epithelial tumors in terms of shapes (p = 0.049), contours (p = 0.018), and CT values (p = 0.012). CONCLUSION: The prevalence of asymptomatic mediastinal masses on low-dose chest CT was 1.68%. CT values, shapes, and contours may effectively distinguish intrathymic cysts from thymic epithelial tumors.

Computed tomography (CT)-derived radiomic features differentiate prevascular mediastinum masses as thymic neoplasms versus lymphomas.

OBJECTIVES: We aimed to assess the ability of radiomics, applied to not-enhanced computed tomography (CT), to differentiate mediastinal masses as thymic neoplasms vs lymphomas. METHODS: The present study was an observational retrospective trial. Inclusion criteria were pathology-proven thymic neoplasia or lymphoma with mediastinal localization, availability of CT. Exclusion criteria were age < 16 years and mediastinal lymphoma lesion < 4 cm. We selected 108 patients (M:F = 47:61, median age 48 years, range 17-79) and divided them into a training and a validation group. Radiomic features were used as predictors in linear discriminant analysis. We built different radiomic models considering segmentation software and resampling setting. Clinical variables were used as predictors to build a clinical model. Scoring metrics included sensitivity, specificity, accuracy and area under the curve (AUC). Wilcoxon paired test was used to compare the AUCs. RESULTS: Fifty-five patients were affected by thymic neoplasia and 53 by lymphoma. In the validation analysis, the best radiomics model sensitivity, specificity, accuracy and AUC resulted 76.2 ± 7.0, 77.8 ± 5.5, 76.9 ± 6.0 and 0.84 ± 0.06, respectively. In the validation analysis of the clinical model, the same metrics resulted 95.2 ± 7.0, 88.9 ± 8.9, 92.3 ± 8.5 and 0.98 ± 0.07, respectively. The AUCs of the best radiomic and the clinical model not differed. CONCLUSIONS: We developed and validated a CT-based radiomic model able to differentiate mediastinal masses on non-contrast-enhanced images, as thymic neoplasms or lymphoma. The proposed method was not affected by image postprocessing. Therefore, the present image-derived method has the potential to noninvasively support diagnosis in patients with prevascular mediastinal masses with major impact on management of asymptomatic cases.