Sandbox/am

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Overview

Plasma cell myeloma is a monoclonal neoplastic proliferation of plasma cells of bone-marrow derivation, usually multicentric, that eventually infiltrates various organs but rarely produces plasma cell leukaemia. It is characterized by osteolytic lesions, bone pain, hypercalcemia, a monoclonal gammopathy, and disorders due to depositon of abnormal immunoglobulin chains (amyloid) in various tissues including kidney. It ranges from MGUS to plasmacytoma to multiple myeloma. Solitary plasmacytoma is a rare plasma cell disorder, accounting for 2–10% of plasma cell disorders. It is classified as either solitary extramedullary plasmacytoma (SEP) or solitary bone plasmacytoma. The head and neck are the predominant sites for SEP, and only a small number are associated with serum Most extramedullary plasmacytomas respond to local radiotherapy and have a good prognosis. Although the most common plasma cell dyscrasia is monoclonal gammopathy of undetermined significance (MGUS), closely related disorders include multiple myeloma, solitary plasmacytoma of bone, extramedullary plasmacytoma, waldenstorm's macroglobulinemia, Amyloidosis, light chain deposition disease, paraproteinemia and heavy chain disease. The spectrum of MGUS, solitary plasmacytoma of bone, and asymptomatic and symptomatic multiple myeloma may actually represent a natural progression of the same disease. Prognosis and outcome of PCM, commonly known as multiple myeloma (MM)—the most prevalent and fatal PCN and the second most common hematologic malignancy worldwide—remain grim despite availability of sophisticated conventional treatment protocols (chemotherapy, irradiation, hematopoietic stem cell transplantation) that have been recently supplemented by novel targeted therapies including proteasome inhibitors (bortezomib), immunomodulatory agents (thalidomide, lenalidomide), antibodies to interleukin-6 (IL-6) or its receptor, and a variety of newly emerging inhibitors of cellular signal transduction pathways

Plasma cell neeoplasm can result in several complications:

Impaired immunity. Myeloma cells inhibit the production of antibodies needed for normal immunity. Having multiple myeloma may make you more likely to develop infections, such as pneumonia, sinusitis, bladder or kidney infections, skin infections, and shingles. Bone problems. Multiple myeloma also can affect your bones, leading to erosion of bone mass and fractures. The condition may cause compression of your spinal cord. Signs of this medical emergency include weakness, or even paralysis, in your legs. Impaired kidney function. Multiple myeloma may cause problems with kidney function, including kidney failure. Higher calcium levels in the blood related to eroding bones can interfere with your kidneys' ability to filter your blood's waste. The proteins produced by the myeloma cells can cause similar problems, especially if you become dehydrated. Anemia. As cancerous cells crowd out normal blood cells, multiple myeloma can also cause anemia and other blood problems.

Laboratory findings :

The presence of unexplained anemia, renal dysfunction, a high (ESR), lytic bone lesions, elevated beta globulin, and/or a high serum protein (especially raised globulins or immunoglobulins) may prompt further testing

The screening test for myeloma inlcudes

If symptoms or the results of routine investigations suggest that a patient may have myeloma, then the following investigations should be performed:[2]

FBC. ESR or plasma viscosity. Urea, electrolytes and creatinine. Calcium. Albumin. Uric acid. Protein elctrophoresis: shows the type of paraprotein. Urine protein electrophoresis: looks for the presence of Bence Jones' protein Quantitative immunoglobulin levels (eg IgG, IgA, IgM levels): non-myelomatous immunoglobulin can be suppressed. The level of the myeloma paraprotein can also be used to assess response to treatment. Plain X-ray of symptomatic areas The classic imaging finding in MM is one or more focal osteolytic lesions seen on radiographs

Lateral skull (left) and humeral shaft (right) radiographs of the patient demonstrate multiple focal osteolytic lesions (some with arrows) that will never heal even if patient remains in complete remission for many years. A minority of patients at diagnosis will have normal imaging findings. The presence of one or more focal lesions with 10% or greater plasma cell marrow infiltration establishes symptomatic MM. More than one skeletal focal lesion without marrow infiltration identifies a variant of MM called multiple solitary plasmacytomas, in which image-guided biopsy of focal lesions is key to diagnosis

Osteolytic lesions related to MM are most commonly found in the axial skeleton, skull, shoulder girdle, proximal humeri, ribs, and proximal femurs.2 These lesions are generally investigated by WBXR, which consists of a series of plain X-rays that include the chest, skull, humeri, femurs, and pelvis, as well as antero-posterior and lateral images of the whole spine. According to the current guidelines of the International Myeloma Working Group, WBXR is considered as the gold standard imaging modality.3 However, this technique has significant limitations. First of all, WBXR is insensitive to detect early osteolytic bone lesions and can, therefore, underestimate the extent of BM involvement.4 An experimental study showed that a bone defect in a lumbar vertebra can be seen on lateral X-ray only when 50–75% of the trabecular bone has been destroyed.5 Additionally, because WBXR requires 20 separate films, the patient generally spends a long period of time on the radiographic table. Furthermore, the WBXR cannot be used to assess treatment response, as the appearance of osteolytic lesions may not change following therapy.

PET

Active focal lesions of MM are well-circumscribed areas of increased uptake on PET or abnormal signal on MRI that an experienced imaging provider interprets as most likely to represent tumor. To avoid excessive false-positives, a finding must be at least 5 mm in diameter to be considered a focal lesion (10).

Current trends :--

Toxicity

Treatment-related toxic effects of existing agents pose another challenge. Peripheral neuropathy is observed in approximately 40% of patients who receive bortezomib (1.3 mg/m) twice weekly, with 14% of patients experiencing grade 3–4 neuropathy, and in approximately 25% of patients who receive the same dose once weekly, including 4% with grade 3–4 sensory neuropathy.46 2 Transplant eligible patient Three-drug induction Two-drug induction Bortezomib–dexamethasone or lenalidomide–dexamethasone Peripheral neuropathy seems to be less frequent and less severe when bortezomib is administered subcutaneously rather than intravenously. In most cases, neuropathy is reversible after discontinuation of bortezomib. Venous thromboembolism (VTE) is observed inapproximately 1–5% of patients in clinical trials with single-agent thalidomide, which is similar to the backgroundrate of such events in patients with multiple myelom who are not treated with this agent. 47 The reported frequency of thrombotic events has been as high as 26% when thalidomide is used in combination with high-dose dexamethasone. As with thalidomide, the risk of VTE among patients with multiple myeloma who take single-agent lenalidomide does not seem to be higher than that of those who do not take lenalidomide does not seem to be higher than those who take it. 49 . By contrast, the use of lenalidomide in combina- tion with high-dose glucocorticoids is associated with 3 fold increased risk of cotting events.48 43 . Although VTE is the most-common form of thrombosisin this patient population,arterial thrombotic events have also been reported. The International Myeloma Working Group panel recommends the use of aspirin in patients with one risk factor for VTE. 50 Individual risk factors for thrombosis associated with thalidomide or lenalidomide-based therapy include age, history of VTE, central venous catheter, comorbidities (infections, diabetes, cardiac disease), immobilization, surgery and inherited thrombophilia. Myeloma-related risk factors include diagnosis and hyperviscosity. 49 49 Low-molecularweight heparin (equivalent to enoxaparin 40 mg per day) is recommended for patients with two or more individual or myeloma-related risk factors for VTE. Heparin is also recommended for all patients receiving thalidomide and lenalidomide in combination with high-dose dexamethasone or doxorubicin. Warfarin given to a therapeutic international normalized ratio of 2–3 is an alternative to heparin, although data in the literature about this strategy are limited. 51 With increasing complexity of drug regimens, the question that remains to be answered is how to individualize the type and intensity of treatment. VTE is observed inapproximately 1–5% of patients in clinical trials with single-agent thalidomide, which is similar to the background rate of such events in patients with multiple myeloma who are not treated with this agent. 47 The reported frequency of thrombotic events has been as high as 26% when thalidomide is used in combination with high-dose dexamethasone. As with thalidomide, the risk of VTE among patients with multiple myeloma who take single-agent lenalidomide does not seem to be higher than that of those who do not take lenalidomide does not seem to be higher than those who take it. 49 . By contrast, the use of lenalidomide in combination with high-dose glucocorticoids is associated with 3 fold increased risk of cotting events.48 43

It is observed in approximately 40% of patients who receive bortezomib (1.3 mg/m) twice weekly, with 14% of patients experiencing grade 3–4 neuropathy, and in approximately 25% of patients who receive the same dose once weekly, including 4% with grade 3–4 sensory neuropathy.46 2 .Peripheral neuropathy seems to be less frequent and less severe when bortezomib is administered subcutaneously rather than intravenously. In most cases, neuropathy is reversible after discontinuation of bortezomib.