Dipeptidyl peptidase IV (DPP IV/CD26) staining predicts distant metastasisof 'benign' thyroid tumor

Because follicular thyroid carcinoma is extremely difficult to diagnose, se veral cases were encountered which have been rediagnosed as carcinoma due t o distant metastasis, In the search for a method of correctly diagnosing 'b enign' thyroid tumor, dipeptidyl peptidase (DPP) IV immunostaining was appl ied to 10 cases whose diagnoses had been corrected to follicular thyroid ca rcinoma because of distant metastases, The positive rate of immunostaining using paraffin sections in the rediagnosed follicular thyroid carcinoma gro up (7/10) was much higher than that of the control group (1/29), which cons isted of 15 cases of follicular thyroid adenoma and 14 cases of nodular hyp erplasia, These results suggested that pre- or postoperative DPP IV stainin g is useful for predicting distant metastasis of 'benign' thyroid tumor.