[Testicular biopsy at the stopping of the treatment in acute lymphoblastic leukemia: value of the immunohistochemical detection of residual blasts].

BACKGROUND

The prognostic value of clinical and histological detection of testicular leukemia after completion of therapy is still debated. Immunohistochemical study could improve the results of this detection.

PATIENTS AND

METHODS

Between 1982 and 1992, 70 consecutive boys with acute lymphoblastic leukemia (ALL) and treated with the same therapeutic regimen were included in the study. Testicular biopsy (TB) was surgical and bilateral. One piece of tissue was fixed and analysed by conventional microscopy. An immunohistochemical study was performed on the other sample with a panel of anti-T and anti-B Mc 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 TB, one had a diffuse infiltration seen in conventional histology. Thirty-nine had normal morphological and immunohistochemical study: among them, six relapsed subsequently in bone marrow; in this group, event free survival (EFS) was 85 +/- 10% with a median follow-up of 80 months after the biopsy. In the 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).

CONCLUSIONS

New Mc Ab such as JCB 117 (anti-CD79a) might detect a minimal residual disease in the testes of children treated for ALL, particularly on routine histological material. These results, if confirmed in larger series, might influence further therapeutic strategy.