Retroperitoneal mass presentations of B-immunoblastic sarcoma.

A clinicopathologic analysis of nine patients with B-immunoblastic sarcoma (B-IBS) presenting as a bulky lymph node-based retroperitoneal mass is reported. The histologic and immunologic findings, similar to those reported in B-IBS presenting in various other nodal and extranodal sites, support the recognition of this aggressive large cell non-Hodgkin's lymphoma (NHL) as a distinct pathologic entity. The patients, with a mean age of 60.5 years, presented for evaluation of abdominal pain and a palpable abdominal mass. Four patients were Stage II or IIE, one Stage III, and four Stage IV; eight of nine had B symptoms. Chemotherapy (cyclophosphamide, doxorubicin, vincristine, prednisone, bleomycin [CHOP-B] or cyclophosphamide, doxorubicin, vincristine, methotrexate with leucovorin rescue, cytarabine [ACOMLA]) yielded significant palliation in five patients (mean survival, 12.3 months); three untreated patients and one receiving radiation treatment (XRT) died within 1 month from diagnosis. There was a striking predilection for pleuropulmonary involvement in disseminating disease. The initial blood lymphocyte count correlated significantly with survival (correlation coefficient, 0.84). The one durable complete remission (CR) was obtained in a patient who received substantial surgical debulking before chemotherapy.