Cytokeratin profiles of the thymus and thymomas: histogenetic correlations and proposal for a histological classification of thymomas

Abstract

The thymus is a complex epithelial organ composed of heterogeneous cell types giving rise to various related histological types of thymoma. The results of the CK profile study supports the proposed histological classification, which is pathologically applicable and clinically useful in correlating with invasiveness. This cytomorphological classification, supported by the CK expression patterns, is comparable to Müller-Hermelink classification and the new WHO histological classification except that a separate group of SPC thymoma expressing only CK14 and CK19 was identified and separated from mixed thymoma.

Classification of thymic epithelial neoplasms: a controversial issue coming to an end?

“…1) [2]. Our classification was supported by the cytokeratin immunohistochemical expression patterns [2] (Table 2). Different classifications are compared in Table 3.…”

“…They even consider all thymomas to be potentially malignant. Another school of pathologists, on the other hand, believe that thymomas can be histologically subclassified despite their complex histomorphology and that the various histological types correlate with their aggressiveness and clinical behavior [2,[11][12][13]20]. Müller-Hermelink's histogenetic classification [4,5,11] belongs to the second group.…”

“…Thymus is a complex lymphoepithelial organ composed of at least four different types of epithelial cells providing a microenvironment for the maturation and differentiation of T lymphocytes [1,2]. Thymomas as tumors arising from thymic epithelial cells reflect this complexity by exhibiting a variety of histomorphologic types [3].…”

“…The evolution of a correct concept of the thymoma and various problems involved in the classification of thymic epithelial tumors will be reviewed. A recently proposed simple histopathological classification based on the cytomorphological features [2] is described for comparison with other classification systems currently in use [1,4,5].…”

Primary pleural thymoma: A mimic in thoracic pathology

“…An awareness of these interpretative pitfalls is important to prevent misdiagnosis of malignant pleural mesothelioma (Table 1) [9] . The morphological diversity of thymic epithelial tumours is illustrated by the WHO classification [17] . Thymic epithelial tumours may range from a pure spindle cell proliferation (Type A thymoma) to an epithelial polygonal cell neoplasm with a variable lymphoid component (Type AB, B1, B2, and B3).…”