Leukemia derived from intermediately differentiated lymphocytic lymphoma.

The availability of monoclonal antibodies has facilitated the immunophenotypic characterization of malignant lymphocytes from patients with lymphoma and leukemia. The chronic lymphocytic leukemias are diseases of both clinical and morphological diversity and the application of monoclonal antibodies can prove helpful in their classification. Enzyme cytochemistry, surface markers, mouse rosetting, and electron microscopy were used to determine the phenotype of cells from an atypical case of B-CLL. The use of monoclonals Leu-1, CALLA and BA-2 on bone marrow and peripheral blood provided the opportunity to diagnose this patient's disease as intermediately differentiated lymphoma. Leu-1 was found to be a useful alternative to mouse rosetting, a technique not easily performed in a routine setting. Ultrastructural studies helped to prove the prolymphocytic component of this patient's disease. It was concluded that phenotypic characterization of lymphoid cells using monoclonal antibodies directed against membrane antigens facilitated the assessment of this patient's disease.