Flow cytometric analysis of lymphoid cells in thymic epithelial neoplasms

Thymic cancer: A not-so-indolent cause of pericardial effusion

The incidence of pericardial effusion in the U.S. is roughly 3.4% [1]. While most causes of pericardial effusions are indolent and transient, malignancy is a much more insidious cause that cannot be overlooked. Most cases of documented pericardial effusion secondary to malignancy have been due to mass effect from benign thymic tumors, such as thymomas. Our case highlights a 41-year-old male who presented with a dry cough and epigastric pain, found to have a large pericardial effusion and incidental thymic mass. The mass was biopsied and found to be keratinizing squamous cell carcinoma. This case expands our knowledge base as clinicians that pericardial effusions can be caused by malignant extension of tumors, rather than simply by mass effect of benign tumors.

The Usefulness of Positron-Emission Tomography Findings in the Management of Anterior Mediastinal Tumors

PURPOSE

We performed a retrospective analysis to evaluate the usefulness of positron-emission tomography/computed tomography (PET/CT) findings in the classification and management of anterior mediastinal tumors.

METHODS

Between 2006 and 2015, 105 patients with anterior mediastinal tumor received PET/CT. 18F-fluorodeoxyglucose (18F-FDG)-PET images were obtained 60 minutes after the injection of 18F-FDG.

RESULTS

The histological classifications were as follows: thymoma (n = 49), thymic carcinoma (TC) (n = 19), malignant lymphoma (ML) (n = 8), teratoma (n = 7), thymic cyst (n = 14), and others (n = 8). Upon visual inspection (SUV max: >2.0), all of the malignant tumors showed 18F-FDG accumulation (with the exception of one type A thymoma). Two of the 14 thymic cysts and three of the seven teratomas showed slight 18F-FDG accumulation. The SUV max values of the low-grade thymomas, high-grade thymomas, TCs and MLs were 3.14 ± 0.73, 4.34 ± 1.49, 8.59 ± 3.05, and 10.08 ± 2.53, respectively, with significant differences between the low- and high-grade thymomas, and between TCs and MLs. The sensitivity, specificity and accuracy of 18F-FDG in the detection of low-grade thymomas and thymomas with a maximum diameter of ≤50 mm and an SUV max of ≤3.4 were 85%, 48%, and 60%, respectively.

CONCLUSION

FDG-PET/CT is an objective and useful modality in the differential diagnosis and management of anterior mediastinal tumors.

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.

Respiratory Tract and Mediastinum

Normal cytology, abnormal and atypical cells, non-cellular components, and infectious cell changes are largely described together with benign, malignant, and neuroendocrine lesions regarding exfoliative and aspiration cytology of the lung. A separate section broadly addresses diagnostic findings and differential diagnoses in bronchoalveolar washings.

The section ‘Fine needle aspiration biopsy of mediastinal disorders’ covers in particular biopsy techniques, accuracy of liquid-based cytology, and the complex lesions of the thymus gland. Cytodiagnostic algorithms of the major benign and malignant pulmonary and mediastinal lesions and their respective differential diagnoses are additionally presented in synoptic setups.

Amygdaloid kindled seizures can induce functional and pathological changes in thymus of rat: role of the sympathetic nervous system

The present study sought to determine the effects of long-term kindled seizures of the basal amygdala upon immune function in rat, utilizing the thymus, as a principal target for study. Histopathology from kindled Sprague-Dawley rats revealed the presence of epithelial cell thymoma in 70% of these rats. The results revealed an increased rate of apoptosis and proliferation in thymic epithelial cells. Analysis of thymocytes indicated a decrease in the ratio of CD4 to CD8 positive T cells and reduced proliferative response to T-cell mitogens. To determine whether these effects were mediated through the sympathetic nervous system, animals were treated with guanethidine, which blocked the development of epithelial cell thymomas, while mifepristone treatment, employed to determine the possible role of the hypothalamic-pituitary axis, was ineffective in attenuating thymoma development. Thus, the present study demonstrated that functional and pathological changes in the thymus during kindled seizures are mediated through the sympathetic nervous system.

Rearrangement of T-cell receptor beta and gamma genes in thymoma

To investigate the differentiation stage of tumor-infiltrating lymphocytes in thymoma tissue, we performed Southern blot analysis of T-cell receptor beta and gamma genes in thymomas resected from 19 patients. At the same time, we conducted flow cytometric analysis of T-cell surface markers and examined the clinicopathological features of the thymomas. We found that the incidence of T-cell receptor gamma gene rearrangement was significantly higher in Masaoka stage I thymomas (11 of 12 cases) than in stage II or III invasive thymomas (3 of 7 cases). Moreover, gamma gene rearrangement was observed in all 10 type AB and B1 thymoma specimens and in 4 of 6 type B2 thymoma specimens. The 2 specimens of type B3 thymomas, which were classified as stage III, showed neither gamma nor beta gene arrangement and were single-positive for CD4 or CD8. Six thymoma specimens that showed beta gene rearrangement expressed both CD4 and CD8. In conclusion, thymomas have the capability of T-lineage cell differentiation, except for a subset of invasive thymomas with malignant characteristics.

Applications of Flow Cytometry and Immunohistochemistry to Diagnostic Hematopathology

Objective.—Diagnostic hematopathology depends on the applications of flow cytometric immunophenotyping and immunohistochemical immunophenotyping combined with the cytomorphology and histologic features of each case. Select cases may require additional ancillary cytogenetic and molecular studies for diagnosis. The purpose of this review is to focus on the applications of flow cytometric and immunohistochemical immunophenotyping of paraffin-embedded tissue to diagnostic hematopathology. Advantages and disadvantages of these techniques are examined.

Data Sources.—The literature is extensively reviewed (PubMed 1985–2003) with an emphasis on the most recent applications and those that are most useful clinically, both diagnostically and prognostically.

Study Selection.—Studies were selected based on statistically significant results in large studies with reported adequate clinical follow-up.

Data Extraction.—The methodology was reviewed in the selected studies to ensure reliable comparison of reported data.

Data Synthesis.—Flow cytometric immunophenotyping offers the sensitive detection of antigens for which antibodies may not be available for paraffin immunohistochemical immunophenotyping. However, paraffin immunohistochemical immunophenotyping offers preservation of architecture and evaluation of expression of some proteins, which may not be available by flow cytometric immunophenotyping. These techniques should be used as complimentary tools in diagnostic hematopathology.

Conclusions.—There are extensive applications of flow cytometric and immunohistochemical immunophenotyping to diagnostic hematopathology. As cytogenetic and molecular findings evolve in diagnostic hematopathology, there may be additional applications of flow cytometric and immunohistochemical immunophenotyping to this field of pathology.