Histologic types of thymoma associated with pure red cell aplasia: A studyof five cases including a composite tumor of organoid thymoma associated with an unusual lipofibroadenoma

The histologic type of thymomas associated with pure red cell aplasia (PRCA ) has generally been regarded to be predominantly the spindle cell type. Th e 5 thymomas associated with PRCA we studied showed various histologic type s and none of them was a spindle cell thymoma. Some cases reported as spind le cell thymoma associated with PRCA in the literature might not be spindle cell type. The discrepancy could be due to the lack of consensus in the hi stologic classification of thymomas in the past. Our study showed that thym omas associated with PRCA lacked a strong correlation with a particular his tologic type and the pathogenesis of PRCA associated with thy moma did not seem to be related to the histologic type. One of our cases was an un usual composite tumor of an organoid thymoma (WHO type B1) and a hitherto undesc ribed "lipofibroadenoma." The clinical outcome was influenced by the invasi ve character and the histologic type of the thymoma.