To elucidate the aetiology of Castleman disease, especially with regard to microRNA (miRNA) profiles, samples obtained from three different parts of both normal and tumour tissues were analysed. The details of RNA extraction have been described in our previous reports. Interestingly, 3 miRNAs were significantly up-regulated and 31 miRNAs were down-regulated in the tumour tissues compared to the normal tissues (Student’s t-test, p<0.01). In addition, unsupervised hierarchical clustering analysis using a Pearson’s correlation showed that the tumour tissues clustered separately from the normal tissues. Overall design: microRNA samples obtained from three different parts of both normal and tumour tissues were analysed.