Terminal transferase positive cells in testicular biopsy specimens from boys with acute lymphoblastic leukaemia.

Thirty nine testicular biopsy samples from 37 boys with acute lymphoblastic leukaemia were examined histologically and analysed for the presence of terminal deoxynucleotidyl transferase (TdT) positive cells. Immunological and histological findings correlated in 35 samples. Thirty boys with histologically and immunologically negative biopsy specimens stopped treatment, two subsequently relapsed in the testis, and five relapsed in the marrow. This examination of samples for TdT positive cells did not improve the precision of early diagnosis of testicular relapse.