Plasma cell leukaemia--a report of two cases.
D Prabhat, SJ Bijur, AV Pathare
Department of Pathology, Seth G.S. Medical College, Mumbai.
Department of Pathology, Seth G.S. Medical College, Mumbai.
Two cases of plasma cell leukaemia--a rare form of leukaemia are described. Both cases presented with anaemia and hepatosplenomegaly. Investigations revealed leucocytosis with increased plasma cells (> 20%). Skeletal survey revealed a few osteolytic lesions in both cases.
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Prabhat D, Bijur S J, Pathare A V. Plasma cell leukaemia--a report of two cases. J Postgrad Med 1998;44:47-9
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Prabhat D, Bijur S J, Pathare A V. Plasma cell leukaemia--a report of two cases. J Postgrad Med [serial online] 1998 [cited 2022 Jul 3 ];44:47-9
Available from: https://www.jpgmonline.com/text.asp?1998/44/2/47/377
Plasma cell leukaemia (PCL) is a rare plasma cell dyscrasia that can develop either de novo or in patients with pre-existing multiple myeloma. The criterion for the diagnosis of PCL is the presence of more than 20% of plasma cells in the peripheral blood or an absolute number of plasma cells exceeding 2 X 109/L. We report here two cases of plasma cell leukaemia.
Case 1: A 55-year-old female patient had low-grade fever, anorexia, nausea and dyspnoea on exertion for two months. On examination, there was severe pallor. The liver and spleen were palpable 2 cms below the costal margin. The left inguinal lymph node was also palpable. Investigations revealed haemoglobin (Hb) of 3.9 gm/dl, total white blood cells (WBC) count 24 X 109/L and the platelet count as 140 X 109/L. Peripheral smear showed rouleaux formation of RBCs. Differential WBC count was plasma cells 49%, neutrophils 32% and lymphocytes 19%. The plasma cells were of variable maturity [Figure:1]. The erythrocyte sedimentation rate (ESR) was 78 mm at the end of one hour by Westergren’s method. The bone marrow aspirate showed increased cellularity with plasma cells constituting about 90% of all the marrow cells. The plasma cells were of varying degrees of maturity ranging from mature ones with abundant basophilic cytoplasm and eccentric nuclei to immature ones with pale blue cytoplasm and nuclei showing prominent nucleoli (Plasmoblasts). Binucleate forms were also seen.
X-ray skull revealed few punched out osteolytic lesions. The serum electrophoresis showed a ‘M’ band in the gamma region [Figure:2]. Immunoelectrophoresis of serum showed increased levels of IgG 8300 mg% (normal - 1180 to 2100 mg%), and decreased levels of IgM - 40 mg% (normal - 85 to 185 mg%). Bence Jones proteins were negative. The BUN was 65 mg% with serum creatinine was 5.4 mg%.
Case 2: A 65-year-old female patient had fatigability, difficulty in walking for one month and dyspnoea on exertion for three months. On examination, she had severe pallor and bone tenderness. The liver and spleen were palpable just below the coastal margin. Investigations revealed Hb 4.1 gm/dl, total WBC count 26.8 x 109/L and platelets were reduced with a count of 70 X 109//L. The peripheral blood smear revealed a few areas of rouleaux formation of the RBCs. The differential WBC count was plasma cells 44%, neutrophils 18%, lymphocytes 34%, myelocytes and metamyelocytes 4 %. An occasional normoblast was also seen. The ESR was 75 mm at the end of one hour by Westergren’s method. The bone marrow aspirate was dilute and plasma cells constituted about 80% of all marrow cells. The plasma cells were of varying maturity. The bone marrow biopsy revealed hypercellularity with almost complete replacement by plasma cells and plasmablasts.
X-ray skull revealed irregular osteolytic lesions. There was Bence Jones proteinuria with urine electrophoresis showing a band of myeloma proteins. Serum electrophoresis showed decreased gamma globulins with no ‘M’ band. The BUN was 86mg% and serum creatinine was 5.2 mg%
In both the cases, a diagnosis of primary plasma cell leukaemia was made and the patient started on Melphelan and Prednisolone. Case 1 received only one cycle of chemotherapy and Case 2 received three cycles of chemotherapy. Thereafter, both these patients were lost to follow up.
There are two forms of plasma cell leukaemia. The primary form occurs in individuals without preceding multiple myeloma whereas the secondary form typically arises as a late manifestation in individuals with multiple myeloma,. It develops in 1-2% of cases of multiple myeloma. The exact incidence of primary plasma cell leukaemia is unknown, but it is believed to be less than one case per million. Hepatosplenomegaly and lymphadenopathy are more common in primary than in secondary plasma cell leukaemia. The lytic bone lesions are more common in patients with secondary plasma cell leukaemia (100% versus 60%). Our first case had hepatosplenomegaly and lymphadenopathy with few lytic bone lesions whereas the second case had hepatosplenomegaly with irregular lytic bone lesions in the skull. Anaemia with a haemoglobin of less than 9 gm/dl occurs in 80% of cases of plasma cells leukaemia versus 35% of cases of multiple myeloma. In both our cases, the haemoglobin was very low i.e. 3.9 gm/dl and 4.1 gm/dl. Rouleaux formation is usually evident on the peripheral blood smear; which was seen in both our cases. Thrombocytopenia with platelets less than 100 X 109/L occurs in 50% of patients with PCL versus only 10% of those with multiple myeloma. Leucocytosis ranges from 20 to more than 100 X 109/L with 20% to 100% of plasma cells.
In both our cases, there was leucocytosis. Our first case showed only mild thrombocytopenia and second case showed moderate thrombocytopenia. An elevated ESR is a very common finding as seen in both our cases.
An elevated BUN and/or creatinine occur in 75% of cases of PCL versus only 40% cases multiple myeloma. Values for both these investigations were elevated levels in our cases. Most patients with PCL have a monoclonal IgG heavy chain or light chain in the serum and Bence Jones proteinuria occurs in about 80% of cases. Our first case showed a ‘M’ band with elevated IgG levels in the serum. Our second case showed Bence Jones proteinuria. Primary plasma cell leukaemia has a rapid course with short survival whereas the secondary form may be associated with a more indolent clinical course and survival is variable.
Patients with primary PCL may initially respond better to chemotherapy including single agent drugs commonly used in multiple myeloma. However, resistant disease is expected and a median survival of less than six months for both types of PCL has been observed. Infection and haemorrhage contribute significantly to morbidity and mortality. DIC has also been reported. Secondary PCL rarely responds to chemotherapy.
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