Lymphocytic lymphoma of intermediate differentiation: morphologic, immunophenotypic, and prognostic factors

Diffuse intermediately differentiated lymphocytic lymphoma (IDL) is a rare (approximately 2.5%) histologic subtype of malignant lymphoma. We have reviewed the morphologic, immunophenotypic, and clinical features of this disease in 23 patients treated at the National Cancer Institute in the 25-year period between 1963 and 1988. These tumors are uniformly of B-cell origin, but most of them express the T-cell antigen CD5; lambda light chain was expressed nearly twice as frequently as kappa. Median age at diagnosis was 58 years; all patients presented with stage III or IV disease, and the natural history of disease in these patients was heterogeneous. Median survival of patients was more than 5 years, but those with liver involvement documented by biopsy had a significantly shorter survival. No other prognostic factor or combination of prognostic factors significantly affected survival in this small series; however, patients with high expression of the proliferation-associated nuclear antigen Ki-67, absence of cell-surface antigens CD9 and CD10, and blastic morphology appeared to have poorer survival. Treatment was heterogeneous, but patients who achieved a complete response to combination chemotherapy survived longer than patients who failed to achieve a complete response. Only two patients had complete responses lasting longer than 2 years. Unlike patients with follicular lymphoma, those with relapsed IDL did not undergo histologic progression of the disease to an aggressive lymphoma. However, as with patients with follicular lymphoma, it was possible to observe patients with IDL without therapy for periods up to 5 years. Although a significant minority of patients may have very aggressive disease, it appears that, in most patients, IDL behaves similarly to other lymphomas with indolent histology, and thus, an optimal therapeutic approach has not yet been defined.