Use of the BCR probe to demonstrate extramedullary recurrence of CGL with a T cell lymphoid phenotype following bone marrow transplantation

A case of Philadelphia chromosome (Ph¹) positive chronic leukemia (CGL) is described in which the patient underwent successful treatment with supralethal chemoradiotherapy and allogeneic bone marrow transplantation (BMT) after transformation to blast crisis. Supraclavicular adenopathy developed 5 months after BMT and biopsy revealed a hematopoietic lymphoid neoplasm with an early T cell phenotype. A concurrent bone marrow as microscopically and cytogenetically normal. A metaphase chromosome preparation could not be obtained from nodal tissue. Lymph node DNA, however, was easily extracted and a rearrangement of BCR identical to that in the bone marrow prior to BMT was demonstrated indicating recurrent CGL rather than a de novo lymphoproliferative process. Appropriate therapy for lymphoid blast crisis resulted in a marked regression of measurable disease. The BCR probe may prove to be a useful tool for the diagnosis of CGL when standard cytogenetic techniques cannot be applied.