The Role of Fine Needle Aspiration Cytology in the Diagnosis and Management of Thymic Neoplasia

Type A thymoma: a rare cause of neoplastic cardiac tamponade with long-term survival

Background

The prognosis of thymoma with cardiac tamponade is generally poor. Most of the reported thymomas with cardiac tamponade were type B or type AB (mixed thymoma), and cardiac tamponade due to type A thymoma, which has a better prognosis compared to type B thymoma, is extremely rare.

Case presentation

We encountered a case of cardiac tamponade in a 71-year-old male. He visited our emergency department due to exacerbation of fatigue and dyspnea on exertion that lasted for two weeks. Chest imaging revealed a large amount of pericardial fluid and a contrast-enhanced tumor with calcification in the anterior mediastinum. The patient underwent thoracoscopic tumor biopsy and pathological examinations revealed type A thymoma. In this case, long-term disease-free survival (7.5 years) was achieved by multidisciplinary treatment (preoperative chemotherapy, surgical excision, and postoperative radiation therapy), in accordance with the histological type.

Conclusions

This case indicates that neoplastic cardiac tamponade, even in elderly patients, should not necessarily be regarded as a terminal cancer and requires a systematic investigation for underlying causes.

Diagnostic Challenges in the Cytology of Thymic Epithelial Neoplasms

Simple Summary

Thymic epithelial neoplasms, including thymoma, thymic carcinoma, and thymic neuroendocrine neoplasms, constitute the majority of anterior mediastinal masses. Fine needle aspirations (FNA) of mediastinal masses are infrequently encountered and are highly challenging to interpret. Thymic neoplasms display a significant degree of histologic diversity and have overlapping morphologic features with tumors from other sites. However, when properly interpreted alongside ancillary studies and radiologic findings, FNAs can yield clinically actionable results. This review aims to illustrate the usefulness and diagnostic pitfalls of thymic FNAs to assist pathologists in analyzing these specimens.

Abstract

Thymic epithelial neoplasms are rare tumors that constitute the majority of anterior mediastinal masses. They are classified as thymomas, thymic carcinomas, and thymic neuroendocrine neoplasms. Biopsy diagnosis is not common, and most tumors are surgically resected. Biopsy, including cytology, is indicated when a non-surgical entity is suspected or in cases of locally advanced disease. Smears of thymomas consist of round or spindle epithelial cells admixed with varying amounts of lymphocytes depending on the type of thymoma. Smears of thymic carcinoma and thymic neuroendocrine neoplasms are often indistinguishable from corresponding tumor types from other organs. Accurate cytological diagnosis can be difficult due to the histological diversity of thymomas, as well as the morphological features that certain thymic tumors share with similar tumors from other organs. However, fine needle aspiration (FNA) of anterior mediastinal masses can provide clinically actionable information and can be used to determine whether lesions require surgical, systemic, or local noninvasive treatments. Ancillary studies, namely, immunocytochemical stains, flow cytometry, and radiology, are important tools in the evaluation of thymic aspirates. This review discusses the utility and limitations of thymic FNAs and illustrates the diagnostic features and pitfalls of these specimens.

Successful Diagnosis of a Thymoma by Endobronchial Ultrasound-guided Transbronchial Needle Aspiration: A Report of Two Cases

We herein report two cases of thymomas diagnosed by endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA). In both cases, the tumor was adjacent to the central airway. Therefore, we attempted to perform EBUS-TBNA in order to obtain specimens for a histopathological examination, which resulted in a diagnosis of thymoma. In one case, surgical resection was conducted and the histological evaluation of the resected specimen confirmed thymoma type AB, consistent with the histology from the EBUS-TBNA specimen. As a safe and minimally invasive procedure, EBUS-TBNA may be considered for the diagnosis of mediastinal tumors, including thymoma.

Diagnosis and subclassification of thymoma by minimally invasive fine needle aspiration directed by endobronchial ultrasound: a review and discussion of four cases

Thymomas have been classified by the World Health Organisation (WHO) into six groups, based on the morphology of epithelial cells and the ratio between epithelial cells and lymphocytes within the tumour. Among 1458 consecutive cases of endobronchial ultrasound transbronchial needle aspiration (EBUS-TBNA) performed in a tertiary referral centre between February 2008 and February 2012, we have encountered four cases of thymic neoplasms. We discuss the cytomorphological features of three cases of type B thymoma (one each of B1, B2 and B3 subtypes) and one case of thymic carcinoma diagnosed on EBUS-TBNA using cell blocks, immunocytochemistry and flow cytometry which allowed preoperative chemotherapy to be carried out in two cases, diagnosis to be made after unsatisfactory surgical mediastinoscopy in the third and diagnosis of lymph node metastasis of the thymic carcinoma in the fourth. The differential diagnosis and criteria for subclassification of thymomas are discussed; although subclassification of these cases was possible in these cases, and tumours other than thymoma excluded, additional cases would be necessary to assess the potential accuracy of EBUS-TBNA. These, to the best of our knowledge, represent the first cases of thymoma that were diagnosed and subclassified according to WHO criteria using multimodality evaluation of EBUS-derived cytological aspirates.

Acute respiratory distress due to thymoma in a patient treated with TK inhibitor: a case report and review of the current treatment options

Thymic malignancies are rare intrathoracic tumors that may be aggressive and difficult to treat in advanced stage. Surgery is the cornerstone of the management of thymomas: it is significant for the definite histopathological diagnosis and staging, and in most cases, it constitutes the first step of the treatment strategy. For patients with primary unresectable thymomas, the multimodal treatment schedule nowadays includes neoadjuvant chemotherapy, extensive surgery, adjuvant radiotherapy, and in some cases, adjuvant chemotherapy. A patient with a history of stage III COPD and an undiagnosed thoracic mass was admitted to the intensive care unit with acute respiratory distress. A radiologic evaluation by CT scan revealed a mass of 13 cm in diameter at the mediastinum. Fine needle aspiration was performed and revealed a thymoma. Due to poor performance status, the patient was not able to undergo surgery. He refused to be treated with neither chemotherapy nor radiotherapy, but due to EGFR overexpression, treatment with TK inhibitor was suggested. Fine needle aspiration biopsy is commonly used to identify metastasis to the mediastinum. However, it is less often employed as a primary diagnostic tool for tumors, particularly thymic neoplasms. The use of targeted therapies for the treatment of thymic malignancies has been described in the literature. Over the past years, significant efforts have been made to dissect the molecular pathways involved in the carcinogenesis of these tumors. Insights have been obtained following anecdotal clinical responses to targeted therapies, and large-scale genomic analyses have been conducted.