Pathology of the Pleura and Mediastinum

2018 Edition
| Editors: Timothy Craig Allen, Saul Suster

Atypical Thymoma

  • David SusterEmail author
  • Paul VanderLaan
Reference work entry


Epithelial-rich thymoma; Epithelial thymoma; Squamoid thymoma; Well-differentiated thymic carcinoma; WHO type B3 thymoma


Atypical thymoma is defined as a moderately differentiated thymic epithelial neoplasm that retains some of the organotypical features of differentiation of the thymus combined with mild to moderate cytologic atypia. These tumors are roughly equivalent to the type B3 thymoma in the WHO classification schema. The tumors are composed of round to polygonal or oval to spindle-shaped epithelial cells with scattered immature lymphocytes.

Atypical thymomas are a tumor of adults occurring between the ages of 14 and 78 with an average age of 45–50 years; as of yet, no discernible sex predilection has been observed. Like other thymic tumors, patients tend to present either asymptomatically or with symptoms related to mass effect of the tumor on adjacent mediastinal structures, such as chest pain, cough, or dyspnea. Rarely, these tumors have been associated...

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References and Further Reading

  1. Inoue, M., Starostik, P., & Zettl, A. (2003). Correlating genetic aberrations with World Health Organization-defined histology and stages across the spectrum of thymomas. Cancer Research, 63, 3708–3718.PubMedGoogle Scholar
  2. Okumura, M., Ohta, M., Tateyama, H., Tada, H., Eimoto, T., Matsuda, H., & Masaoka, A. (2002). The world health organization histologic classification system reflects the oncologic behavior of thymoma: A clinical study of 273 patients. Cancer, 94, 624–632.CrossRefPubMedGoogle Scholar
  3. Suster, S., & Moran, C. A. (1996). Primary thymic epithelial neoplasms with combined features of thymoma and thymic carcinoma: A clinicopathologic study of 22 cases. American Journal of Surgical Pathology, 20, 1469–1480.CrossRefPubMedGoogle Scholar
  4. Suster, S., & Moran, C. A. (1999). Thymoma, atypical thymoma and thymic carcinoma. A novel conceptual approach to the classification of neoplasms of thymic epithelium. American Journal of Clinical Pathology, 111, 826–833.CrossRefPubMedGoogle Scholar
  5. Suster, S., & Moran, C. A. (2009). The mediastinum. In N. Weidner, R. Cote, S. Suster, & L. Weiss (Eds.), Modern surgical pathology (2nd ed., Vol. 1, pp. 454–516). Philadelphia: Saunders Elsevier.CrossRefGoogle Scholar
  6. Travis, W. D., Brambilla, E., Burke A. P., Marx A., & Nicholson A. G. (Eds.). (2015). WHO classification of tumours of the lung, pleura, thymus and heart. Lyon: IARC Press 4th ed.Google Scholar

Copyright information

© Springer International Publishing AG, part of Springer Nature 2018

Authors and Affiliations

  1. 1.Beth Israel Deaconess Medical Center and Harvard Medical SchoolBostonUSA