TESTICULAR BIOPSY AFTER COMPLETION OF THE RAPY IN ACUTE LYMPHOBLASTIC-LEUKEMIA - RELEVANCE OF IMMUNOHISTOCHEMICAL DETECTION OF RESIDUAL BLASTS

Background. - The prognostic value of clinical and histological detect ion of testicular leukemia after completion of therapy is still debate d. Immunohistochemical study could improve the results of this detecti on. Patients and methods. - Between 1982 and 1992, 70 consecutive boys with acute lymphoblastic leukemia (ALL) and treated with the same the rapeutic regimen were included in the study. Testicular biopsy (TB) wa s surgical and bilateral. One piece of tissue was fixed and analysed b y conventional microscopy. An immunohistochemical study was performed on the other sample with a panel of anti-T and anti-B Me Ab, including JCB 117 (anti-CD79a) which stains early pre B lymphoblasts. Results. - Twenty-five children relapsed while on treatment and did not undergo TB. Among the 45 boys who underwent routine TBI one had a diffuse inf iltration seen in conventional histology. Thirty-nine had normal morph ological and immunohistochemical study: among them, six relapsed subse quently in bone marrow; in this group, event free survival (EFS) was 8 5 +/- 10% with a median follow-up of 80 months after the biopsy. In th e five remaining boys, anti-CD79a was found positive on blasts in four cases and anti-CD3 in one case: four of those relapsed, including two in the testes during the year following the biopsy; EFS was 20 +/- 36 % (P = 0.001). Conclusion. - New Me Ab such as JCB 117 (anti-CD79a) mi ght detect a minimal residual disease in the testes of children treate d for ALL, particularly on routine histological material. These result s, if confirmed in larger series, might influence further therapeutic strategy.