Primary tumors of the thymus and mediastinum represent a heterogenous group of lesions that encompass tumors originating from many different cell types. Of these, tumors arising from thymic epithelial cells are the most common. These tumors include multiple types of thymoma, different types of carcinomas, and neuroendocrine tumors. Amongst these there is a wide spectrum of histomorphology that can present difficulty for the classification and diagnosis of these lesions. This is compounded by the fact that the thymus and mediastinum are located in close proximity to multiple other anatomical structures including the lungs, heart, great vessels, various nerves and other respiratory and digestive tract structures. Tumors from these structures, particularly carcinomas of the lung, may show morphologic overlap with primary tumors of the thymus and mediastinum and if large enough may be located partially within the mediastinum and involve thymic structures. In addition, these tumors are exceedingly rare compared tumors more commonly encountered in other organ systems making them more difficult to study in large numbers. Uncertainty over the definitive classification of these lesions, potential difficulty with surgical resection, and lack of consensus guidelines for the management of patients with thymic epithelial neoplasms makes them oftentimes difficult tumors to manage when encountered in routine practice. Finally, unlike many epithelial tumors that have been well characterized in other organ systems, relatively little genetic information exists regarding these tumors and the histogenesis of many of them remains uncertain. Unlike colon or lung cancer, very few recurrent, specific driver alterations have been identified in thymic tumors and virtually no molecular alterations have been discovered that make tumors amenable to treatment with targeted therapies. This issue aims to discuss and review many topics related to the diagnosis, management, and classification of thymic epithelial tumors.
The following topics will be discussed:
Radiological Characteristics of Thymic Epithelial Neoplasms
Treatment and Management of Primary Thymic Epithelial Tumors
Histopathological Classification of Thymoma
Histopathological Classification of Thymic Carcinoma
Histopathological Classification of Primary Thymic Neuroendocrine Tumors
Surgical Management of Primary Thymic Tumors
Molecular Genetic Landscape of Thymoma and Thymic Carcinoma
Histopathological Classification of Rare Thymic Tumors
Proposed articles and authors
1. "Histopathologic Classification of Thymic Epithelial Neoplasms" (Commentary); David Suster, M.D. and Saul Suster, M.D.
2. "Staging of Thymic Epithelial Neoplasms" (Commentary): Cesar A. Moran, M.D., Professor of Pathology, M.D. Anderson Cancer Center, Houston, TX.
3. "Distinctive Patterns of Immunohistochemical Expression of β-Catenin, E-Cadherin, PAX8, Bcl-2, EMA and MIB1 in Thymomas" (Original Contribution), David Suster, M.D. and Saul Suster, M.D., Rutgers University School of Medicine, Newark, NJ.
4. "Molecular Genetics of Thymic Epithelial Neoplasms" (Review): David Suster, M.D, and Alexander C. Mackinnon, M.D., Ph.D., University of Alabama.
5. "The Role of Imaging Studies in the Diagnosis of Thymic Epithelial Neoplasms" (Review): Justin T. Stowell, M.D., Department of Radiology, Mayo Clinic, JACKSONVILLE, FL.
6. "Thymic Neuroendocrine Neoplasms" (Review): Yin P. Hung, M.D., Massachusetts General Hospital and Harvard Medical School, Boston, MA.
7. "Thymic Carcinoma: Review and Update" (Review): Phillip Michaels, M.D., Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA.
8. "Role of Radiation Oncology in the Management of Thymic Epithelial Neoplasms" (Review): Candice Johnston, M.D., Department of Radiation Oncology, Medical College of Wisconsin. The list is arranged in no particular order and being updated.