Ultrastructural aspects of bone marrow and peripheral blood cells in a case of plasma cell leukemia

Plasma cell leukemia: a report on 15 patients

Plasma cell leukemia (PCL) can be considered the leukemic variant of multiple myeloma. The diagnosis is based on hematological features, including a plasmacytosis exceeding 2 x 10(9)/l and any evidence of a clonal plasma cell proliferation. There are two forms of PCL: the primary form occurring in individuals without preceding multiple myeloma, and the secondary form arising as a late manifestation in patients with multiple myeloma. From 1974 to 1988 we diagnosed 8 primary PCL cases out of a total 301 multiple myeloma cases (incidence, 2.6%) and a total of 847 acute leukemia cases (incidence, 0.9%). During the same period we observed in 7 multiple myeloma patients a terminal PCL, for an incidence of PCL in myeloma of 2.3%. Most clinical characteristics were similar in both types of plasma cell leukemia. In particular we found no difference in the average age and in the incidence of bone pain, hepatosplenomegaly, lytic bone lesions. None of our cases showed a clinically relevant lymphadenopathy either as presenting symptom or during the course of the disease. The values for hemoglobin, leukocytes, plasma cells, serum creatinine and calcium did not differ significantly between the two groups of patients. The median survival was 7 months for patients with primary PCL and 1 month for patients with secondary PCL. 5 of the 8 patients with primary PCL obtained a response to conventional myeloma therapy including single alkylating agents, with a duration ranging from 7 to 44 months. Only 1 of the patients with secondary PCL had a partial response after combination chemotherapy.

Plasma cell leukemia: an evaluation of response to therapy

Forty-three patients with plasma cell leukemia were seen at the Mayo Clinic. Twenty-five (58 percent) had primary plasma cell leukemia (diagnosis first made in the leukemic phase) and 18 (42 percent) had secondary plasma cell leukemia (leukemic transformation of a previously diagnosed multiple myeloma). Patients with secondary plasma cell leukemia were older, had a greater incidence of lytic bone lesions, had a lower platelet count, and had a larger M-protein in the serum than did patients with primary plasma cell leukemia. The median survival was 6.8 months for patients with primary plasma cell leukemia and 1.3 months for patients with secondary plasma cell leukemia. In patients with primary plasma cell leukemia, multiple alkylating agents produced a higher response rate than did melphalan, but the median time from treatment to progression or death was not significantly improved with such therapy. Review of the literature also suggests that the response rate is higher with combination chemotherapy than with single alkylating agents. Patients with secondary plasma cell leukemia usually show resistance to any type of chemotherapy and have a short survival.

Transmission and scanning electron microscopy study on plasma cell leukemia

The peripheral blood cells of a patient with acute plasma cell leukemia were examined with transmission (TEM) and scanning (SEM) electron microscopes. The TEM features of the immature plasma cells comprised lobulated and irregulary shaped nuclei, with scanty heterochromating and bizarre nucleoli, parallel arrays of endoplasmic reticulum, cytoplasmic fibrils and numerous polymorphic mitochondria. SEM examination of the cells showed long, thin irregular ruffles, or round blebs on the cell surface, with appearance different from this observed on other types of leukemia. A remarkable clinical and hematological remission was achieved with administration of melphalan and steroids.

Multiple myeloma terminating in lymphocytic leukemia with B-lymphocyte membrane markers

The development of lymphocytic leukemia with a rapidly fatal clinical course is reported in a patient with kappa light-chain multiple myeloma treated with alkeran. The leukemic cells lacked the ultrastructural features of plasma cells but bore readily detectable B-cell markers and resembled lymphocytes under the light, transmission, and scanning electron microscopes. The leukemic phase is perhaps best defined as lymphocytic and probably represents a variant of plasma cell leukemia, in which the cells showed a degree of dedifferentiation from plasma cells to B lymphocytes. The possible relation between these 2 proliferative processes is discussed and the nature of leukemias developing in cases of plasma cell myeloma is briefly reviewed.