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Micronodular thymoma with lymphoid stroma: an immunohistochemical study of the distribution of Langerhans cells and mature dendritic cells in six patients
Author(s) -
Ishikawa Yoshinori,
Tateyama Hisashi,
Yoshida Megumi,
Takami Koji,
Matsuguma Haruhisa,
Taniguchi Tetsuo,
Usami Noriyasu,
Kawaguchi Koji,
Fukui Takayuki,
Ishiguro Futoshi,
Nakamura Shota,
Yokoi Kohei
Publication year - 2015
Publication title -
histopathology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.626
H-Index - 124
eISSN - 1365-2559
pISSN - 0309-0167
DOI - 10.1111/his.12428
Subject(s) - thymoma , stroma , pathology , stromal cell , immunohistochemistry , biology , follicular dendritic cells , hyperplasia , lymphatic system , antigen , immune system , medicine , t cell , immunology , antigen presenting cell
Aims Micronodular thymoma with lymphoid stroma ( MNT ) is an uncommon variant of thymoma, characterized by multiple small nodules consisting of type A thymoma‐like cells, which are separated by abundant B lymphocytes. The aim of the study was to elucidate the pathogenesis of the stromal lymphoid hyperplasia, which is currently unclear. Methods and results We retrieved six cases of MNT , and immunohistochemically examined the number and distribution of Langerhans cells ( LC s) and mature dendritic cells ( DC s), and compared them with those in type A and type AB thymomas. Many LC s were present within the small tumour nests, but LC s were rarely seen in the stroma (75.5/ HPF versus 6.1/ HPF , P < 0.0001). In contrast, mature DC s were present mainly in the surrounding stroma rather than within the tumour nodules (63.5/ HPF versus 6.0/ HPF , P < 0.0001), forming clusters with mature T lymphocytes adjacent to lymphoid follicles. In large nodules, as well as in type A and type AB thymomas, a few scattered LC s and DC s were identified. All patients were still alive and well. Conclusions Our results suggest that LC s take up tumour antigens and migrate to the stroma, where they mature and form clusters with T lymphocytes to activate them, resulting in lymphoid follicle formation. The favourable clinical behaviour may be attributable to the immune response induced by LC s.