Thymic Imaging Pitfalls and Strategies for Optimized Diagnosis.

Thymic imaging is challenging because the imaging appearance of a variety of benign and malignant thymic conditions are similar. CT is the most commonly used modality for mediastinal imaging, while MRI and fluorine 18 fluorodeoxyglucose (FDG) PET/CT are helpful when they are tailored to the correct indication. Each of these imaging modalities has limitations and technical pitfalls that may lead to an incorrect diagnosis and mismanagement. CT may not be sufficient for the characterization of cystic thymic processes and differentiation between thymic hyperplasia and thymic tumors. MRI can be used to overcome these limitations but is subject to other potential pitfalls such as an equivocal decrease in signal intensity at chemical shift imaging, size limitations, unusual signal intensity for cysts, subtraction artifacts, pseudonodularity on T2-weighted MR images, early imaging misinterpretation, flow and spatial resolution issues hampering assessment of local invasion, and the overlap of apparent diffusion coefficients between malignant and benign thymic entities. FDG PET/CT is not routinely indicated due to some overlap in FDG uptake between thymomas and benign thymic processes. However, it is useful for staging and follow-up of aggressive tumors (eg, thymic carcinoma), particularly for detection of occult metastatic disease. Pitfalls in imaging after treatment of thymic malignancies relate to technical challenges such as postthymectomy sternotomy streak metal artifacts, differentiation of postsurgical thymic bed changes from tumor recurrence, or human error with typical "blind spots" for identification of metastatic disease. Understanding these pitfalls enables appropriate selection of imaging modalities, improves diagnostic accuracy, and guides patient treatment. ©RSNA, 2024 Test Your Knowledge questions for this article are available in the supplemental material.

A basaloid carcinoma with multilocular thymic cyst mimicking a mediastinal teratoma.

This case report details a rare thymic basaloid carcinoma initially misinterpreted as a mediastinal teratoma, underscoring the diagnostic challenges posed by such tumors. A 71-year-old female presented with an asymptomatic anterior mediastinal tumor discovered incidentally during a routine health examination. Surgical intervention, followed by pathological and immunohistochemical analysis including CK-pan, p63, p40, and CD117 molecules, led to a definitive diagnosis of basaloid carcinoma of the thymus. This case highlights the critical importance of differential diagnosis in mediastinal lesions, especially those presenting with multilocular thymic cysts on chest CT. The subxiphoid video-assisted thoracoscopic surgery enabled complete tumor resection with minimal trauma and favorable postoperative outcomes. The patient opted against further radiotherapy or chemotherapy and she has survived for over eight months without recurrence. This case report contributes to the growing understanding of thymic basaloid carcinoma, a rare and potentially aggressive thymic carcinoma subtype. It emphasizes the necessity for precise surgical techniques and enhanced diagnostic acumen among cardiothoracic surgeons and oncologists.

ESCO2's oncogenic role in human tumors: a pan-cancer analysis and experimental validation.

PURPOSE: Establishment of sister chromatid cohesion N-acetyltransferase 2 (ESCO2) is involved in the mitotic S-phase adhesins acetylation and is responsible for bridging two sister chromatids. However, present ESCO2 cancer research is limited to a few cancers. No systematic pan-cancer analysis has been conducted to investigate its role in diagnosis, prognosis, and effector function. METHODS: We thoroughly examined the ESCO2 carcinogenesis in pan-cancer by combining public databases such as The Cancer Genome Atlas (TCGA), Genotype-Tissue Expression Project (GTEx), UALCAN and Tumor Immune Single-cell Hub (TISCH). The analysis includes differential expression analysis, survival analysis, cellular effector function, gene mutation, single cell analysis, and tumor immune cell infiltration. Furthermore, we confirmed ESCO2's impacts on clear cell renal cell carcinoma (ccRCC) cells' proliferative and invasive capacities in vitro. RESULTS: In our study, 30 of 33 cancer types exhibited considerably greater levels of ESCO2 expression in tumor tissue using TCGA and GTEx databases, whereas acute myeloid leukemia (LAML) exhibited significantly lower levels. Kaplan-Meier survival analyses in adrenocortical carcinoma (ACC), kidney chromophobe (KICH), kidney renal clear cell carcinoma (KIRC), kidney renal papillary cell carcinoma (KIRP), brain lower grade glioma (LGG), liver hepatocellular carcinoma (LIHC), lung adenocarcinoma (LUAD), mesothelioma (MESO), and pancreatic adenocarcinoma (PAAD) demonstrated that tumor patients with high ESCO2 expression have short survival periods. However, in thymoma (THYM), colon adenocarcinoma (COAD) and rectum adenocarcinoma (READ), ESCO2 was a favorable prognostic factor. Moreover, ESCO2 expression positively correlates with tumor stage and tumor size in several cancers, including LIHC, KIRC, KIRP and LUAD. Function analysis revealed that ESCO2 participates in mitosis, cell cycle, DNA damage repair, and other processes. CDK1 was identified as a downstream gene regulated by ESCO2. Furthermore, ESCO2 might also be implicated in immune cell infiltration. Finally, ESCO2'S knockdown significantly inhibited the A498 and T24 cells' proliferation, invasion, and migration. CONCLUSIONS: In conclusion, ESCO2 is a possible pan-cancer biomarker and oncogene that can reliably predict the prognosis of cancer patients. ESCO2 was also implicated in the cell cycle and proliferation regulation. In a nutshell, ESCO2 is a therapeutically viable and dependable target.

Analysis of 25 surgical cases of thymic neuroendocrine tumors and thymic carcinoma.

BACKGROUND: The purpose of this study was to evaluate the clinicopathological characteristics of patients who underwent surgical resection for thymic neuroendocrine tumors (TNET) or thymic carcinoma. METHODS: In this study, we retrospectively evaluated the clinicopathological characteristics of our surgical patients at Fukuoka University Hospital from January 1995 to December 2018. RESULTS: There were nine cases of TNET and 16 cases of thymic carcinoma. Regarding the pathological type, the TNET group included three atypical carcinoid cases, two large cell neuroendocrine tumor cases, two small cell carcinoma cases, and two other cases. The thymic carcinoma group included 15 squamous carcinoma cases and one case of adenosquamous carcinoma. Based on the Masaoka-Koga staging system, six TNET cases and 11 thymic carcinoma cases were stage III or IV. The complete resection rate was 77% in the TNET group and 81% in the thymic carcinoma group. Additional chemotherapy and/or radiotherapy was performed in five cases of TNET and 11 cases of thymic carcinoma. The five-year survival rate and five-year disease-free survival rate were 87.5% and 75.0% in the TNET group and 58.9% and 57.1% in the thymic carcinoma group, respectively, with no significant difference between the two groups (P = 0.248 and P = 0.894, respectively). In the univariate analysis, complete resection was a statistically significant prognostic factor (P = 0.017). CONCLUSION: In this study, no difference in prognosis was observed between TNET and thymic carcinomas. To understand the characteristics of these tumors, further case accumulation and multicenter clinical studies are needed. (243words).

Complete resection of a giant intrapericardial cardiac synovial sarcoma.

Synovial sarcoma of the heart is a rare tumor. Herein we would like to report a case of giant intrapericardial cardiac synovial sarcoma that originated from the right ventricle and grew outward near the diaphragm. After making adequate preoperative preparation, we performed the surgery as quickly as possible and resected the tumor completely. Based on the identification of the translocation on chromosome 18 rearrangement, the tumor can be diagnosed as a primary cardiac synovial sarcoma. Through this study, we aim to afford more information about cardiac synovial sarcomas as well as a reference for similar cases.

Autoimmunity in thymic epithelial tumors: a not yet clarified pathologic paradigm associated with several unmet clinical needs.

Thymic epithelial tumors (TETs) are rare mediastinal cancers originating from the thymus, classified in two main histotypes: thymoma and thymic carcinoma (TC). TETs affect a primary lymphoid organ playing a critical role in keeping T-cell homeostasis and ensuring an adequate immunological tolerance against "self". In particular, thymomas and not TC are frequently associated with autoimmune diseases (ADs), with Myasthenia Gravis being the most common AD present in 30% of patients with thymoma. This comorbidity, in addition to negatively affecting the quality and duration of patients' life, reduces the spectrum of the available therapeutic options. Indeed, the presence of autoimmunity represents an exclusion criteria for the administration of the newest immunotherapeutic treatments with checkpoint inhibitors. The pathophysiological correlation between TETs and autoimmunity remains a mystery. Several studies have demonstrated the presence of a residual and active thymopoiesis in adult patients affected by thymomas, especially in mixed and lymphocytic-rich thymomas, currently known as type AB and B thymomas. The aim of this review is to provide the state of art in regard to the histological features of the different TET histotype, to the role of the different immune cells infiltrating tumor microenvironments and their impact in the break of central immunologic thymic tolerance in thymomas. We discuss here both cellular and molecular immunologic mechanisms inducing the onset of autoimmunity in TETs, limiting the portfolio of therapeutic strategies against TETs and greatly impacting the prognosis of associated autoimmune diseases.

Anti-Interleukin-23 Autoantibodies in Adult-Onset Immunodeficiency.

BACKGROUND: Autoantibodies against interleukin-12 (anti-interleukin-12) are often identified in patients with thymoma, but opportunistic infections develop in only some of these patients. Interleukin-12 (with subunits p40 and p35) shares a common subunit with interleukin-23 (subunits p40 and p19). In a patient with disseminated Burkholderia gladioli infection, the identification of both anti-interleukin-23 and anti-interleukin-12 prompted further investigation. METHODS: Among the patients (most of whom had thymoma) who were known to have anti-interleukin-12, we screened for autoantibodies against interleukin-23 (anti-interleukin-23). To validate the potential role of anti-interleukin-23 with respect to opportunistic infection, we tested a second cohort of patients with thymoma as well as patients without either thymoma or known anti-interleukin-12 who had unusual infections. RESULTS: Among 30 patients with anti-interleukin-12 who had severe mycobacterial, bacterial, or fungal infections, 15 (50%) also had autoantibodies that neutralized interleukin-23. The potency of such neutralization was correlated with the severity of these infections. The neutralizing activity of anti-interleukin-12 alone was not associated with infection. In the validation cohort of 91 patients with thymoma, the presence of anti-interleukin-23 was associated with infection status in 74 patients (81%). Overall, neutralizing anti-interleukin-23 was detected in 30 of 116 patients (26%) with thymoma and in 30 of 36 patients (83%) with disseminated, cerebral, or pulmonary infections. Anti-interleukin-23 was present in 6 of 32 patients (19%) with severe intracellular infections and in 2 of 16 patients (12%) with unusual intracranial infections, including Cladophialophora bantiana and Mycobacterium avium complex. CONCLUSIONS: Among patients with a variety of mycobacterial, bacterial, or fungal infections, the presence of neutralizing anti-interleukin-23 was associated with severe, persistent opportunistic infections. (Funded by the National Institute of Allergy and Infectious Diseases and others.).

Paraneoplastic autoimmune neurologic disorders associated with thymoma.

Thymoma is often associated with paraneoplastic neurologic diseases. Neural autoantibody testing is an important tool aiding diagnosis of thymoma and its autoimmune neurologic complications. Autoantibodies specific for muscle striational antigens and ion channels of the ligand-gated nicotinic acetylcholine receptor superfamily are the most prevalent biomarkers. The autoimmune neurologic disorders associating most commonly with thymoma are myasthenia gravis (MG), peripheral nerve hyperexcitability (neuromyotonia and Morvan syndrome), dysautonomia, and encephalitis. Patients presenting with these neurologic disorders should be screened for thymoma at diagnosis. Although they can cause profound disability, they usually respond to immunotherapy and treatment of the thymoma. Worsening of the neurologic disorder following surgical removal of a thymoma may herald tumor recurrence. Prompt recognition of paraneoplastic neurologic disorders is critical for patient management. A multidisciplinary approach is required for optimal management of neurologic autoimmunity associated with thymoma.

Robotic portal resection for mediastinal tumours: a prospective observational study.

BACKGROUND: To demonstrate the effectiveness and feasibility of robotic portal resection (RPR) for mediastinal tumour using a prospectively collected database. METHODS: Data from 73 consecutive patients with mediastinal tumours who underwent RPRs were prospectively collected from August 2018 to April 2023. All patients underwent chest and abdominal enhanced computed tomography (CT) and preoperative multidisciplinary team (MDT) discussion. The patients were stratified into two groups based on tumour size: Group A (tumour size < 4 cm) and Group B (tumour size ≥ 4 cm). General clinical characteristics, surgical procedures, and short outcomes were promptly recorded. RESULTS: All of the cases were scheduled for RPRs. One patient (1/73, 1.4%) was switched to a small utility incision approach because of extensive pleural adhesion. Two patients (2.8%) converted to sternotomy, however, no perioperative deaths occurred. Most of the tumours were located in the anterior mediastinum (51/73, 69.9%). Thymoma (27/73, 37.0%) and thymic cyst (16/73, 21.9%) were the most common diagnoses. The median diameter of tumours was 3.2 cm (IQR, 2.4-4.5 cm). The median total operative time was 61.0 min (IQR, 50.0-90.0 min). The median intraoperative blood loss was 20 mL (IQR, 5.0-30.0 ml), and only one patient (1.4%) experienced an intraoperative complication. The median length of hospital stay was 3 days (IQR, 2-4 days). Compared with Group A, the median total operative time and console time of Group B were significantly longer (P = 0.006 and P = 0.003, respectively). The volume of drainage on the first postoperative day was greater in group B than in group A (P = 0.013). CONCLUSION: RPR is a safe and effective technique for mediastinal tumour treatment, which can expand the application of minimally invasive surgery for the removal of complicated mediastinal tumours.

Unusual presentation and delayed diagnosis of cardiac angiosarcoma.

BACKGROUND: Primary cardiac angiosarcomas are very rare and present aggressively with high rates of metastasis. Given the poor prognosis, particularly once disease has spread, early diagnosis and multidisciplinary treatment is essential. CASE PRESENTATION: We present the case of a 46-year-old male who presented with chest pain, intermittent fevers, and dyspnea. Workup with computed tomography scan and transesophageal echocardiography demonstrated a right atrial pseudoaneurysm. Given the concern for rupture, the patient was taken to the operating room, where resection of the pseudoaneurysm and repair using a bovine pericardial patch was performed. Histopathology report initially demonstrated perivascular lymphocyte infiltrate. Six weeks later, the patient represented with chest pain and new word finding difficulty. Workup revealed multiple solid lung, pericardial, brain, and bone nodules. Eventual biopsy of a cardiophrenic nodule demonstrated angiosarcoma, and rereview of the original pathology slides confirmed the diagnosis of primary cardiac angiosarcoma. CONCLUSIONS: Primary cardiac angiosarcomas are often misdiagnosed given the rarity of these tumors, but early diagnosis and initiation of treatment is essential. The unique presentation of our case demonstrates that clinical suspicion for cardiac angiosarcoma should be maintained for spontaneous pseudoaneurysm originating from the right atrium.

Carcinoma showing thymus-like elements (CASTLE) with amyloid deposition in the parotid gland.

Carcinoma showing thymus-like elements (CASTLE) is a rare tumor that commonly occurs in the thyroid gland. Extrathyroidal CASTLE is rarer, and only 11 cases of CASTLE of major salivary glands have been reported to date. We report the first case of amyloid deposition in parotid CASTLE. A 63-year-old man presented with a slowly growing mass in the left parotid region. Computed tomography revealed an approximately 28 × 23 mm mass lesion in the left parotid gland, and squamous cell carcinoma was suspected on biopsy. The patient underwent a parotidectomy with neck dissection. Morphologically, the tumor cells were squamoid and formed nests with lymphoid infiltration. Immunohistochemically, the tumor cells exhibited immunoreactivity for CD5, CD117/c-kit and Bcl-2, p40, and CK5 but not for p16. We diagnosed the tumor as parotid CASTLE. Amyloid deposition was also observed in the primary tumor and metastatic lymph node lesions, which were immunoreactive for cytokeratin 5. Tumor cytokeratin-derived amyloid deposition may be one of characteristics of parotid CASTLE.

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.

The modified Lyon's position: an alternative approach to robotic thymectomy.

The conventional supine position for robotic thymectomy may present challenges in accessing the lower thymic horns, particularly in cases requiring extensive resection of mediastinal fat. To address this issue, the authors advocate for a lateral patient position during the procedure, emphasizing optimized access to the thymic horns and improved procedural efficacy. The lateral approach involves specific trocar placements and port arrangements to minimize conflicts between instruments. This report proposes an innovative approach to robotic thymectomy for patients diagnosed with thymoma or thymic hyperplasia associated with myasthenia gravis.