The spectrum of ectopic thymomas

Ectopic pleural thymoma with T-cell lymphocytosis and bone metastasis: a case report

BACKGROUND

The diagnostic complexities that arise in radiographic distinction between ectopic pleural thymoma and other thoracic neoplasms are substantial, with instances of co-occurring T-cell lymphocytosis and osseous metastasis being exceedingly rare.

CASE PRESENTATION

A 51-year-old woman was admitted to our hospital with dyspnea and chest pain. Upon imaging examination, she was found to have diffuse and nodular pleural thickening on the left side, collapse of the left lung and a compression in the second thoracic vertebrae. All lesions showed significant 18F-FDG uptake on 18F-FDG PET/CT examination. Furthermore, she exhibited T-cell lymphocytosis in her peripheral blood, lymph nodes, and bone marrow. After ruling out malignant pleural mesothelioma (MPM), lung cancer with pleural metastasis, and T-cell lymphoma, the definitive diagnosis asserted was ectopic pleural thymoma with T-cell lymphocytosis and bone metastasis.

CONCLUSION

Physicians need to expand their knowledge of the imaging features of ectopic pleural thymoma. Cases with T-cell lymphocytosis may exhibit increased aggressiveness and prone to bone metastasis.

Making an accurate diagnosis of anterior mediastinal lesions: a proposal for a new diagnostic algorithm from the BTOG Thymic Malignancies Special Interest Group

Due to the rising demand in cross-sectional thoracic imaging, anterior mediastinal lesions are being identified with increasing frequency. Following iterative and multidisciplinary discussions, the BTOG Thymic Malignancies Special Interest Group have developed an algorithm to standardise the diagnostic approach for these relatively uncommon but important conditions which span from benign (thymic remnant, thymic hyperplasia and thymic cysts) to suspected localised thymomas to suspected more aggressive malignancy (thymic carcinoma, lymphoma and germ cell tumours). For each condition, we provide a brief description, an overview of the key radiological findings and a description of the proposed algorithm including the rationale behind the recommendations. We also highlight the role of magnetic resonance (MR) imaging for the characterisation of anterior mediastinal masses in specific indications when the necessary local resources and expertise exist. In addition, we hope this provides the rationale for service development in MR of the anterior mediastinum where current resource and expertise requires development. Through this standardised pathway, we hope to drive improvements in patient care by rationalising surveillance schedules, avoiding unnecessary resections of benign entities with their associated morbidity and optimising the diagnostic work-up prior to the appropriate treatment of anterior mediastinal malignancies.

Ectopic Cervical Thymoma in a Patient Diagnosed With Graves Disease: A Systematic Literature Review

Thymomas are benign thymic epithelial neoplasms, rarely found outside the anterior mediastinum. Although hyperthyroid states have been associated with thymic hyperplasia, only 3 thymoma cases have been previously reported in patients with Graves disease (GD), all within the anterior mediastinum. Here, we report a case of ectopic cervical thymoma in a 22-year-old female patient previously treated for GD. The patient underwent ultrasonography, computed tomography, inconclusive fine-needle aspiration, and ultimately gross dissection for diagnostic workup and definitive treatment of an anterior neck mass, producing a 2.5 × 2.3 × 1.5-cm entity consistent with Masaoka stage I and type B2 thymoma per World Health Organization classification. The patient underwent an uncomplicated subsequent clinical course, with no adjuvant radiotherapy administered. After conducting a systematic literature review, we conclude that of the 109 cases of ectopic cervical thymoma reported, this is the first to describe a case of ectopic cervical thymoma in a patient with a past medical history of GD. For GD patients in stable euthyroid remission with the persistent or recurrent presence of an anterior neck mass, the extrathyroidal origin of the mass should always be considered, including the exceptional presence of a cervical ectopic thymoma.

Dataset for reporting of thymic epithelial tumours: recommendations from the International Collaboration on Cancer Reporting (ICCR)

AIMS

Thymic epithelial tumours (TET), including thymomas and thymic carcinomas and thymic neuroendocrine neoplasms, are malignant neoplasms that can be associated with morbidity and mortality. Recently, an updated version of the World Health Organization (WHO) Classification of Thoracic Tumours 5th Edition, 2021 has been released, which included various changes to the classification of these neoplasms. In addition, in 2017 the Union for International Cancer Control (UICC) / American Joint Committee on Cancer (AJCC) published the 8th Edition Staging Manual which, for the first time, includes a TNM staging that is applicable to thymomas, thymic carcinomas, and thymic neuroendocrine neoplasms.

METHODS AND RESULTS

To standardize reporting of resected TET and thymic neuroendocrine neoplasms the accrediting bodies updated their reporting protocols. The International Collaboration on Cancer Reporting (ICCR), which represents a collaboration between various National Associations of Pathology, updated its 2017 histopathology reporting guide on TET and thymic neuroendocrine neoplasms accordingly. This report will highlight important changes in the reporting of TET and thymic neuroendocrine neoplasms based on the 2021 WHO, emphasize the 2017 TNM staging, and also comment on the rigour and various uncertainties for the pathologist when trying to follow that staging.

CONCLUSION

The ICCR dataset provides a comprehensive, standardized template for reporting of resected TET and thymic neuroendocrine neoplasms.

Multifocal primary intrapulmonary thymoma successfully resected via robotic-assisted thoracoscopic surgery

Primary intrapulmonary thymoma (PIT) represents a rare subset of ectopic thymoma that arises solely from inside the pulmonary parenchyma. Multifocal PIT, where multiple isolated PIT origins coexist in the lungs, has only been confirmed in one previous case report, in which the patient died before surgical resection. These tumours are difficult to diagnose as imaging findings are non-specific, and non-invasive biopsy often yields inaccurate results. We present the case of a man in his 70s who was referred to thoracic surgery for resection of a presumptive endobronchial pulmonary carcinoid tumour. Only after surgical resection did we identify that the patient had multifocal PIT. In this report, we describe our diagnostic and management process for this patient and review the current literature on PIT.

An unusual ectopic thymoma clonal evolution analysis: A case report

Thymomas and thymic carcinomas are rare and primary tumors of the mediastinum which is derived from the thymic epithelium. Thymomas are the most common primary anterior mediastinal tumor, while ectopic thymomas are rarer. Mutational profiles of ectopic thymomas may help expand our understanding of the occurrence and treatment options of these tumors. In this report, we sought to elucidate the mutational profiles of two ectopic thymoma nodules to gain deeper understanding of the molecular genetic information of this rare tumor and to provide guidance treatment options. We presented a case of 62-year-old male patient with a postoperative pathological diagnosis of type A mediastinal thymoma and ectopic pulmonary thymoma. After mediastinal lesion resection and thoracoscopic lung wedge resection, the mediastinal thymoma was completely removed, and the patient recovered from the surgery and no recurrence was found by examination until now. Whole exome sequencing was performed on both mediastinal thymoma and ectopic pulmonary thymoma tissue samples of the patient and clonal evolution analysis were further conducted to analyze the genetic characteristics. We identified eight gene mutations that were co-mutated in both lesions. Consistent with a previous exome sequencing analysis of thymic epithelial tumor, HRAS was also observed in both mediastinal lesion and lung lesion tissues. We also evaluated the intratumor heterogeneity of non-silent mutations. The results showed that the mediastinal lesion tissue has higher degree of heterogeneity and the lung lesion tissue has relatively low amount of variant heterogeneity in the detected variants. Through pathology and genomics sequencing detection, we initially revealed the genetic differences between mediastinal thymoma and ectopic thymoma, and clonal evolution analysis showed that these two lesions originated from multi-ancestral regions.

An intrapericardial thymoma resected by uniportal video-assisted thoracoscopic surgery

Thymomas are usually located in the normal location of the thymus in the anterior mediastinum. It is very rare for thymomas to arise primarily intrapericardially. A 76-year-old male patient with a known human immunodeficiency virus positivity and has been under close follow-up for five years was admitted to our clinic. Thoracic computed tomography revealed an intrapericardial mass. Uniportal video-assisted thoracoscopic surgery was performed for the resection of the intrapericardial mass. Pathological examination revealed a type AB thymoma with a 3x3x2.5-cm dimensions (Stage 1). He underwent adjuvant irradiation. He has been doing well without any recurrence for 41 months. In conclusion, resection of intrapericardial masses is feasible and safe. This is the first case with a purely intrapericardial thymoma that was resected via uniportal videoassisted thoracoscopic surgery in the literature.

Intrapericardial Thymoma Presented as Pericardial Tamponade with Post-Operative Myasthenia Gravis

Background: Thymoma is an epithelial mass arising from the thymus. Most thymomas are located in the anterior mediastinum. Ectopic intrapericardial thymoma is very unusual; to date, only eight cases of pericardial thymoma have been reported. Among thymoma patients, 20% to 25% are associated with myasthenia gravis. However, postoperative myasthenia gravis occurs in less than 1% of cases. Here, we share a rare case of ectopic intrapericardial thymoma that developed postoperative myasthenia gravis six months after surgery. Case presentation: A 66-year-old woman visited the outpatient department due to productive cough and chest pain. Chest radiography showed increased soft tissue opacity over the mediastinum. A soft tissue mass in the pericardium and a ground glass nodule in right upper lung were noted using chest computed tomography. The diagnosis of thymoma, type B2, pT3N0M0, and stage IIIA and synchronous adenocarcinoma in situ of the right upper lung was confirmed after surgical removal. Six months later, the patient developed postoperative myasthenia gravis. Conclusions: Thymoma is rarely considered a differential diagnosis in pericardial tumors. Surgical removal with adjuvant radiation therapy should be performed considering the malignancy potential of thymomas and cardiac complications. In patients without myasthenia gravis, a small chance of postoperative myasthenia gravis remains. Patients should be carefully monitored for myasthenia gravis after surgery.

Pre-tracheal Ectopic Thymoma: A diagnostic challenge in Endobronchial Ultrasound-guided Transbronchial Needle Aspiration cytology

Ectopic thymomas (ETs) are rare thymic neoplasms that arise from atypical anatomical sites¹ and present a diagnostic challenge for clinicians as they can be mistaken for other pathological entities on fine needle aspiration (FNA) cytology.² Endobronchial Ultrasound-guided Transbronchial Needle Aspiration (EBUS-TBNA) sampling of mediastinal and para-tracheal lymph nodes is commonly performed to diagnose and stage lung malignancies. International literature search of thymic lesions diagnosed on EBUS-TBNA yielded only four cases although none in an ectopic location. In this report we describe a case of a patient who presented with an ectopic thymoma that was diagnosed by EBUS-TBNA from a station 4R location. Subsequent histology confirmed the diagnosis and subtyped as well as staged the tumour. We discuss the role of cytology in the diagnosis of this rare tumour from an unusual site, the potential pitfalls and highlight the importance of considering ET as a differential diagnosis in the context of unexplained mediastinal lymphadenopathy.

Diagnosis and management of ectopic cervical thymus in children: Systematic review of the literature

BACKGROUND/PURPOSE

Ectopic cervical thymus (ECT) is a rare cause of neck swelling in children. Our aim was to evaluate the diagnostic and management challenges of this condition.

METHODS

Systematic review of the literature (1997-2020) using PRISMA guidelines.

RESULTS

A total of 192 cases of ECT were identified. Forty-two cases (4 studies) were excluded because of insufficient data resulting in 150 cases (7 bilateral) in a total of 143 patients. ECT presented as a solid mass in 71 cases (10 incidentally found at autopsy, 33 conservatively managed and 28 excised) and as a cystic mass in 79 cases (all excised). A total of 165 imaging studies in 123 patients were performed (65 ultrasound scans (USS), 51 magnetic resonance imaging (MRI) scans and 49 computer tomography (CT) scans). ECT was diagnosed by imaging in 18.7% (23/123) of patients. Fine needle aspiration cytology or incisional/needle biopsy were performed in 16% (23/140) cases; a correct diagnosis of ECT was obtained in 52% (12/23) of those cases. There were no reports of malignancy in 143 specimens analysed. A normal mediastinal thymus was absent in 2.5% (1/40) of patients investigated.

CONCLUSIONS

ECT is a benign and relatively rare condition in children that is seldom diagnosed on imaging before tissue sampling or surgical excision. ECT might be the only active thymus in 2.5% of cases and careful consideration should be taken prior to its excision in young children. We recommend that ECT should be considered in the differential diagnosis of neck masses in children. Conservative management might be appropriate in selected cases and the presence of a normal mediastinal thymus in the thorax should be investigated before planning surgical excision.

Multifocal Primary Intrapulmonary Thymoma: A rare subtype of ectopic thymoma

Primary Intrapulmonary Thymoma (PIT) is an infrequent ectopic lung tumor that poses a diagnostic dilemma and has a poorly understood origin. We report a previously healthy 61-year-old lady who presented with cough and weight loss for a month. Diagnostic imaging showed a large left upper lobe mass and two multifocal pleural based nodules in the left lower lobe. She underwent Computed Tomography (CT) guided biopsy of the lung mass and histopathological findings was consistent with a combined Type B1 and B2 thymoma. She was planned for 6 cycles of neoadjuvant chemotherapy with the intent of achieving tumor downstaging and resectability. Due to the lack of established evidence for management of unresectable disease, we wish to highlight the importance of multidisciplinary consensus before pursuing multimodality treatment.

An ectopic thymoma arising in the middle mediastinum that was difficult to distinguish from a lymph node metastasis

BACKGROUND

Ectopic thymomas often occur in the upper mediastinum; however, they rarely arise in the middle mediastinum, especially on the dorsal side of the innominate vein and superior vena cava in the peribronchial region.

CASE PRESENTATION

Six years prior, a 27-year-old female presented to our department and was diagnosed with locally advanced left breast cancer. First, we administered chemotherapy including an anti-human epidermal growth factor receptor 2 antibody. The size of the tumor was markedly reduced, and a radical operation involving mastectomy and axillary lymph node dissection was then performed. The patient underwent radiotherapy after the mastectomy, followed by trastuzumab therapy; she continued to receive endocrine therapy thereafter. She underwent computed tomography once a year after the surgery, and a nodule in the middle mediastinum on the dorsal side of the innominate vein and superior vena cava in the parabronchial region was detected at 4 years. We speculated that the nodule was a solitary mediastinal lymph node metastasis from her breast cancer; therefore, we performed thoracoscopic resection of the tumor. We diagnosed the tumor as a thymoma. Currently, the patient visits our hospital to receive continuous hormone therapy for her breast cancer, and the latest computed tomography scan demonstrated no metastases from or recurrence of her breast cancer or thymoma.

CONCLUSIONS

We report a case of ectopic thymoma in the middle mediastinum. The tumor, which was detected during systemic therapy for locally advanced breast cancer, was located on the dorsal side of the innominate vein and superior vena cava in the parabronchial region and was indistinguishable from a lymph node metastasis from breast cancer.

Myasthenic crisis appearing after resection of intracardiac ectopic thymoma with superior vena cava syndrome

Background

We describe herein an extremely rare case of intracardiac ectopic thymoma—only two pure cases have been reported to date—associated with myasthenia gravis, an infrequent complication of ectopic thymoma.

Case presentation

A 71-year-old woman with superior vena cava syndrome was found to have a large mass mainly located in the right atrium. Tumor resection under cardiopulmonary bypass was performed. The pathological diagnosis was type AB ectopic thymoma. The postoperative course was complicated by progressive respiratory failure, and she was diagnosed with myasthenic crisis based on clinical signs and the edrophonium test. The patient recovered and was weaned from prolonged mechanical ventilation after receiving intravenous immunoglobulin, and was subsequently discharged uneventfully.

Conclusions

This is the first report of myasthenic crisis due to intracardiac ectopic thymoma. Residual thymoma is a risk factor for the development of post-thymectomy myasthenia gravis, and long-term follow-up is required.

Late-onset myasthenia gravis successfully treated with local resection of cervical ectopic thymoma

A 78-year-old woman was admitted complaining progressive respiratory failure, neck weakness and gait disturbance. She was diagnosed as acetylcholine receptor antibody-positive myasthenia gravis crisis with ectopic cervical thymoma. After she recovered from crisis by plasmapheresis and administration of prednisone, we did not choose extended thymectomy but chose local resection of ectopic thymoma considering her age and complications. After the operation, she got minimal manifestations and no relapse of thymoma. Although international and Japanese guidelines recommend extended thymectomy for myasthenia gravis with thymoma, isolated local resection of ectopic thymoma may be enough for controlling myasthenia gravis especially in elderly patients.

Paratracheal Middle Mediastinal Thymic Carcinomas

We describe case studies of two patients who underwent resection of paratracheal middle mediastinal thymic carcinomas. In both patients, complete resection of these masses via right thoracotomy was performed using three-dimensional computed tomography. Final pathologic diagnoses were thymic squamous cell carcinoma and thymic atypical carcinoid tumor. Challenges and debates in preoperative, intraoperative, and postoperative management are discussed in this article.

Ectopic thymoma: Retrospective analysis of eight cases with clinical features and computed tomography findings

OBJECTIVE

To analyze the computed tomography (CT) and clinical features of ectopic thymoma, and to be familiar with the CT diagnosis of this disease.

MATERIALS AND METHODS

CT data, clinical data, and pathological data of eight cases of ectopic thymoma, confirmed by pathology from September 2013 to June 2019, were retrospectively analyzed.

RESULTS

Eight cases of thymoma were diagnosed, which included three in mediastinum (one of B1 type, two of C type), two in pericardium (both of B3 type), one in lung (B1 type), one in pleura (AB type), and one in right atrium (B2 type). Among the eight cases, four were men and four were women, aged 36-70 years. The clinical manifestations were chest tightness, shortness of breath and cough, and one case of myasthenia gravis. Six of the 8 patients were misdiagnosed as lymphoma, solitary fibrous tumor, malignant teratoma by CT. CT showed the following: the long diameter of tumor was 4.2 cm-19.5 cm, the shape was elliptical or round, and one case of ectopic thymoma grew in the atrium. The density was homogeneous in two cases and heterogeneous in six cases. The boundary was clear in three cases and unclear in five cases. Among the eight cases, three showed pleural effusion, two showed pericardial effusion and three showed calcification.

CONCLUSIONS

Ectopic thymoma is rare and often misdiagnosed due to abnormal position. However, CT findings of ectopic thymoma are similar to those of the anterior superior mediastinal thymoma.

[Ectopic thymic tissue and ectopic thymic tumors]

Ectopic thymic tissue outside its core position in the antero-superior mediastinum is quite common owing to the complexity of embryonal thymus development, whereby reported prevalence values (1 to 90%) are heavily dependent on the method of investigation and the intensity of the workup. The debated prevalence and relevance of ectopic thymic tissue and its accessibility underlie the ongoing discussion whether modern, minimally invasive thymectomy strategies can match the proven benefit of the radical transsternal thymectomy procedure for the treatment of Myasthenia gravis. In this context, the following article covers the etiology, prevalence, and location of normal-looking, reactive, and neoplastic ectopic thymic tissue. Furthermore, ectopic tissues and tumors inside or adjacent to the thymus are mentioned.

Ectopic thymoma in the paratracheal region of the middle mediastinum: a rare case report and literature review

Background

Thymomas generally arise from the thymus in the anterior mediastinum. Ectopic thymomas arising in the middle mediastinum are rare. We present a case of a thymoma arising from the ectopic thymic tissue in the right paratracheal region.

Case presentation

The patient was a 67-year-old male who underwent an enhanced-computed tomography examination as preoperative staging for colon cancer. A 20-mm nodule in the right paratracheal region was found incidentally. Fluorodeoxyglucose (FDG) accumulation was detected in this solitary nodule by FDG-positron emission tomography, mimicking an enlarged, possibly malignant lymph node. The tumor was removed by thoracoscopic surgery, and a postoperative pathological diagnosis of type AB thymoma was made. Foci of ectopic thymic tissues were found adjacent to the thymoma. The patient was disease-free and without recurrence 2 years postoperatively.

Conclusions

Including the present case, 13 cases of ectopic paratracheal thymoma have been reported in the English literature, all of which were found on the right side of the paratracheal region. Although ectopic thymomas in the paratracheal region are rare, thymomas may be considered as a differential diagnosis for a paratracheal nodule.

Ectopic thymoma managed by neck dissection & video-assisted thoracoscopic thymectomy

Ectopic thymoma in the neck is a rare phenomenon, with fewer than 20 cases reported worldwide. Evidence for management of ectopic thymoma comes from literature for mediastinal thymoma despite clinical features that distinguish the two. Here we present a case of a 31-year-old female with an asymptomatic neck mass who was found to have an ectopic cervical thymoma with concomitant mediastinal thymic hyperplasia. The decision was made to perform a left-sided neck dissection and a video-assisted thoracoscopic surgery (VATS) thymectomy. We suggest that this approach be considered for a minimally invasive management of this rare but important condition.

Ectopic right parietal pleural thymic carcinoma: a rare case and review of the literature

Ectopic thymic carcinoma is extremely rare. We present a case of a 73-year-old male patient with ectopic right parietal pleural thymic carcinoma and performed a literature review. Computed tomography (CT) of the chest demonstrated a sharp-edged soft tissue mass with intense enhancement measuring 47 mm × 29 mm with a broader base adjacent to the right axillary chest wall at the level of the 5th rib. There was no hilar or mediastinal lymphadenopathy or evidence of a mediastinal tumor or pleural nodules. A totally extra-pleural tumor resection and partial right lung resection was performed. Histological examination demonstrated infiltrative growth typical of carcinoma cells with a nest-like distribution locally invading the surface of the lung tissue. Immunohistochemical examination confirmed the diagnosis of thymic squamous carcinoma positive for CD5. Mediastinal radical radiotherapy (60 Gy) was performed postoperatively. The patient was followed for 17 months without any evidence of recurrence or metastasis.