Thymoma and thymic carcinoma associated with multilocular thymic cyst: a clinicopathologic analysis of 18 cases

First report of a successful surgical management of left atrial myxoma coexisting with pulmonary squamous cell carcinoma and thymic cyst

BACKGROUND

Primary cardiac tumors, while rare, present significant clinical challenges due to their diverse pathology and presentation. Lung cancer frequently metastasizes to the heart; however, cases involving primary cardiac tumors of different origins alongside primary lung cancer are exceedingly rare in the literature.

CASE PRESENTATION

We report the case of a 53-year-old female who presented with hemoptysis and was subsequently diagnosed with a left atrial myxoma, pulmonary squamous cell carcinoma, and a thymic cyst. This coexistence of multiple non-homologous tumors in a single patient is exceedingly rare.

CONCLUSION

This case underscores the complexity of diagnosing and managing patients with multiple distinct tumors. The simultaneous occurrence of a primary cardiac myxoma, pulmonary squamous cell carcinoma, and thymic cyst is unprecedented, providing valuable insights for future clinical practice.

Thymic epithelial tumours: histopathological classification and differential diagnosis

The epithelial and lymphoid compartments of the thymus can give rise to a wide variety of tumours, including thymomas, thymic carcinomas, lymphoreticular proliferations, germ cell tumours, and sarcomas. While some of these have close similarity to their counterparts in other organs, both in terms of histology and immunohistochemistry, as well as molecular features, others are unique to the thymus. The epithelial tumours, which can develop in the thymus, will be discussed in this review, with a particular emphasis on resolving differential diagnosis by means of morphology, immunohistochemical profiles, and molecular diagnostics.

Combined Thymic Epithelial Neoplasms - a Review

Thymic epithelial neoplasms are the most common tumors of thymic origin but are overall rare in the general population. Their morphologic diversity, ranging from low grade to overtly malignant lesions, along with various histologic growth patterns make them a diagnostically challenging group of tumors. Very occasionally, thymomas and thymic carcinomas may develop in combination with other benign or malignant lesions of thymic origin, further complicating the diagnostic process. The focus of this review lies on the spectrum of thymic epithelial tumors that present with other thymic lesions in the same tumor mass, such as multilocular thymic cysts, neuroendocrine neoplasms, lymphomas, and germ cell tumors among others. Awareness of the existence of such unusual tumors may not only aid in their diagnosis but may also have implications for prognostic and therapeutic purposes.

A Cervical Thymic Cyst in an Adult Female; A Case Report and Comprehensive Literature Review

Introduction: Cervical thymic cyst accounts for (0.3-1) % of cervical cysts in children and are usually present during the first decade of life with few reported cases in adults. Herein, we present a 34-year-old female with a cervical thymic cyst. We conducted a review of all the previously reported cases as well. Case presentation: The patient complained of an anterolateral neck swelling that was noticed one year ago. It was a soft, fluctuant, mobile, non-tender swelling in the midline and the right side of the lower neck. Neck ultrasonography revealed a large thin-walled cyst, with no internal septa, echoes, or solid parts. Post-contrast MRI of the neck showed a well-defined, oblong-shaped, lobulated cystic lesion just beneath the strap muscle. The cyst extended caudally to the superior border of the anterior mediastinum at the level of the upper border of the manubrium sterni. The patient underwent excision of the swelling under general anesthesia via Kocher's collar neck incision. Connection with the thymus gland was detected behind the manubrium sterni which was separated. Pathological examination showed prominent thymic tissue confirming the diagnosis of a cervical thymic cyst. Conclusion: Adult cervical thymic cyst is very rare with a few cases reported in the literature. Surgical excision in symptomatic patients is the treatment of choice. Paper's main novel aspects: • A rare presentation of a cervical thymic cyst in an adult. • A comprehensive literature review including all the previously reported cases in one table.

Giant Multilocular-Cystic Metaplastic Thymoma: A Case Report

The metaplastic thymoma with giant multilocular-cyst formation had not been documented. The metaplastic thymoma is an extremely rare primary thymic epithelial tumor with an indolent clinical course. It is characterized by a histologic biphasic appearance, which is consisted of solid epithelial areas and spindle cells as the background. This specific pattern can be easily mistaken as the type A thymoma or the type A components of type AB thymoma. When cystic change occurs in metaplastic thymoma, it will bring more challenges for both imaging and pathological diagnosis. Herein, we reported an extremely rare case of a 14.9-cm giant tumor located in the anterior mediastinum of an elderly female. The tumor is consisted of both multilocular cysts and solid components, with the largest cyst measuring 6 cm in diameter. The multilocular cyst contained hemorrhage, calcification, and cholesterol crystal cracks without cell lining. In the solid area, the epithelial cell nests were surrounded by spindle cells with scattered lymphocytes. With immunostains, neither type of cells was CD20 positive. The epithelial cells were positive for CK and P63, while the spindle cells expressed vimentin and EMA. Fluorescence in situ hybridization analysis revealed that the tumor harbored YAP1-MAML2 gene fusions. Accordingly, although the multilocular cystic pattern set a diagnostic challenge, the diagnosis of metaplastic thymoma was rendered due to the immunohistochemistry staining and YAP1-MAML2 gene rearrangement detection.

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.

Histological Classification and Invasion Prediction of Thymoma by Machine Learning-Based Computed Tomography Imaging

Purpose

The values of machine learning-based computed tomography (CT) imaging in histological classification and invasion prediction of thymoma were investigated.

Methods

181 patients diagnosed with thymoma by surgery or biopsy in Shantou Central Hospital between February 2017 and March 2022 were selected. According to the concept of simplified histological classification and the latest histological classification by the WHO, thymoma was divided into two groups, including low-risk (types A, AB, B1, and metaplastic type) and high-risk groups (types B2 and B3). CT images were reconstructed by filtering back projection (FBP) algorithm. CT image features were collected for statistical analysis.

Results

The main symptoms of patients diagnosed with thymoma included respiratory tract infection, chest distress and shortness of breath, and chest pain. 35.91% of them suffered from complicated myasthenia gravis. Tumor size and position in low-risk and high-risk groups showed no statistical significance (P > 0.05). Tumor morphology and boundary between the two groups suggested statistical difference (P < 0.05). Whether tumor invaded adjacent tissues was apparently correlated with simplified histological classification (P < 0.01). The sensitivity and specificity of CT images for the invasion of mediastinal pleura or pericardium were around 90% and negative predictive values both reached above 95%. Those of the CT images for lung invasion were over 80%. The negative and positive predictive values were 93.54% and 63.82%, respectively. Those of the CT images for blood vessel invasion were 67.32% and 97.93%. The negative and positive predictive values were 98.21% and 83%, respectively.

Conclusion

The machine learning-based CT image had significant values in the prediction of different histological classification and even invasion level.

Thymic squamous cell carcinoma lurking in a growing large cyst A case report

An 81-year-old man was admitted for resection of an asymptomatic left anterior mediastinal tumor. Chest computed tomography showed that a small, homogeneous lesion had grown to a large, cystic lesion (80 mm) over a 5-year period. The cystic tumor was removed with adherent structures such as the left upper pulmonary parenchyma and lower part of the left innominate vein via median sternotomy with assistance from a left thoracoscopic procedure. Macroscopically, a solid tumor was located within the large multilocular cyst. The pathological diagnosis was cystic squamous cell carcinoma (12 mm), which had not infiltrated any surrounding organs. The patient has remained well without recurrence as of 4 years postoperatively.

Multilocular Thymic Cyst in a Patient with Untreated HIV/AIDS: Case Report and Review of the Literature

BACKGROUND

Multilocular thymic cysts (MTCs) in adults with human immunodeficiency virus (HIV) are rarely reported.

CASE PRESENTATION

We describe a case of symptomatic MTC in a male with untreated HIV. A presumptive diagnosis was established based on radiographic imaging and biopsy. Pathologic diagnosis and exclusion of malignancy were ultimately confirmed the following thymectomy. In conjunction with starting antiretroviral therapy, the patient recovered well post-operatively with a resolution of his presenting symptoms.

CONCLUSION

Our case report and review of the literature serve to highlight MTCs as an important clinical entity occurring in persons with HIV.

A rare case of combined thymoma and a multilocular thymic cyst discovered due to chest pain

Background

A thymoma with chest pain and multilocular thymic cysts (MTCs) is very rare.

Case presentation

A 49-year-old man presented to another hospital complaining of an anterior chest pain. Chest computed tomography (CT) showed an anterior mediastinal tumor 60 × 30 × 55 mm in size. The boundary with the pericardium or left brachiocephalic vein seemed to be partially unclear while enhanced by the contrast medium, and so the tumor could have invaded them. No definitive diagnosis of myasthenia gravis was made although the serum anti-acetylcholine receptor antibody count was high. We performed an extended thymectomy with combined partial resection of left brachiocephalic vein, left upper lobe, and left phrenic nerve. He was discharged with no chest pain and no complications post-surgery. The tumor was pathologically type B2 thymoma with hemorrhage necrosis and MTCs, and we diagnosed Masaoka stage II because of no histological infiltration to the organs.

Conclusions

We speculated that hemorrhagic necrosis due to infarction in tumor caused the inflammation to spread to the surrounding organs, which was related to the chest pain and the development of MTCs.

Common and rare carcinomas of the thymus

Thymic carcinoma encompasses a diverse group of rare tumors that occur almost exclusively in the prevascular (anterior) mediastinum. Thymic carcinomas have a worse outcome than thymomas with a median time to death of under 3 years. These tumors lack the typical lobulation of thymomas, exhibit commonly more cytologic atypia, are associated with a desmoplastic stromal reaction, and lack thymocytes, features that distinguish them from thymomas. The most common thymic carcinoma is squamous cell carcinoma; other subtypes include mucoepidermoid carcinoma, NUT carcinoma, and adenocarcinoma, among others. Largely due to multi-institutional and global efforts and meta-analysis of case reports and series, some of the thymic carcinoma subtypes have been studied in more detail and molecular studies have also been performed. Morphology and immunophenotype for the vast majority of thymic carcinoma subtypes are similar to their counterparts in other organs. Therefore, the distinction between thymic carcinoma and metastatic disease, which is relatively common in the prevascular mediastinum, can be challenging and in general requires clinical and radiologic correlation. Although surgical resection is the treatment of choice, only 46 to 68% of patients with thymic carcinoma can undergo resection as many other tumors present at high stage with infiltration into vital neighboring organs. These patients are usually treated with chemotherapy and/or radiation. The search for better biomarkers for prognosis and treatment of thymic carcinomas is important for improved management of these patients and possible targeted therapy.

Anterior mediastinal lesions: CT and MRI features and differential diagnosis

Anterior mediastinum is the most common location of mediastinal tumors, which include various solid and cystic lesions. The lesion location and CT and MRI features are important in the differential diagnosis. Recently, CT-based mediastinal compartment classification systems were proposed and suggested to be useful for accurate evaluation of mediastinal lesions. CT and MRI reflect the pathological findings of mediastinal lesions, and knowledge of the pathological features is important for the differential diagnosis. In this article, we review the CT and MRI features of anterior mediastinal lesions and describe important points in the differential diagnosis.

Non-Neoplastic and Benign Tumoral Lesions of the Thymic Gland: A Review and Update

The thymus is a dynamic organ that undergoes changes throughout life and can demonstrate a myriad of pathologic alterations. A number of benign entities of the thymus prove to be diagnostic dilemmas owing to their resemblance and association with true thymic tumors. These are usually discovered incidentally on routine imaging and most patients are either asymptomatic or present with signs and symptoms of compression of adjacent organs. The radiologic appearance of these lesions varies from simple cysts to complex masses that are suspicious for malignancy. The diagnosis is usually made purely on morphologic grounds, however, immunohistochemical stains can help rule out possible differential diagnoses. Surgical removal is usually curative in these lesions and recurrences are rare. The prognosis is excellent, however, some of these lesions may be associated with myasthenia gravis and/or thymomas. In this review, we describe non-neoplastic lesions and benign tumoral lesions of the thymus, with emphasis on the clinical, radiologic, and pathologic features. The differential diagnosis of each entity is also discussed.