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Recurred Castleman's disease containing a fibrohistiocytic nodular lesion with vascular occlusion

A recurring case of Castleman's disease containing a fibrohistiocytic nodular lesion is presented. The recurred tumor was found in the mediastinum of a 40 year old Japanese female who had undergone the extirpation of a mediastinal tumor 18 years previously and had been suffering from rheumatoid arthritis 5 years after the initial removal. Microscopically, the present tumor and the initial removed tumor fulfilled the morphologic criteria for the hyaline‐vascular type of Castleman's disease. A well‐demarcated nodular lesion (1.5 cm in diameter) was located in the present tumor. It consisted of interlacing oval to short spindle‐shaped cells positive for factor XIIIa and vimentin, merging with lymphocytes, plasma cells, macrophages and capillaries lined by swollen endothelial cells. Mitotic figures were not noted. Foci of hemorrhage and necrosis were also not detected. The stenosis or occlusion of the large vessels due to intimal fibrosis and medial hypertrophy was observed around the nodular lesion.