Interleukin-6-producing undifferentiated thymic carcinoma with neuroendocrine features.

Undifferentiated thymic carcinoma is a rare tumor of the thymus. Due to the extreme rarity of undifferentiated thymic carcinoma, very limited information about its characteristics is available. We encountered an autopsy case of a 33-year-old woman diagnosed as having an undifferentiated thymic carcinoma with a high inflammatory response. The patient's serum interleukin-6 (IL-6) was elevated to 1930 pg/ml, and immunohistochemical staining of the carcinoma cells was positive for neuroendocrine markers and IL-6. To the best of our knowledge, this is the first report of an IL-6-producing undifferentiated thymic carcinoma with neuroendocrine features that shows a novel potential to produce IL-6.