investigated the dna methylation profile of multiple myeloma cells and normal plasma cells, a gradual demethylation from stem cells to plasma cells was observed. the observed methylation pattern of cpg within intronic regions with enhancer-related chromatin marks in multiple myeloma is similar to undifferentiated precursor and stem cells. these results may represent a de novo epigenetic reprogramming in multiple myeloma, leading to the acquisition of a methylation pattern related to stemness. other studies have identified a multiple myeloma specific gene silencing pattern associated with the polycomb repressive complex 2 (prc2). increased expression of the prc2 subunit, ezh2 have been described to be a common feature in multiple myeloma, resulting in an accumulation and redistribution of histone h3 lysine 27 trimethylation which advances with disease severity. genetics chromosomal abnormalities commonly found in this disease, like trisomy of multiple odd-numbered chromosomes, t(11;14), and del(13q), are not associated with a worse prognosis. however, about 25% of patients with newly diagnosed disease have abnormalities associated with a worse prognosis, like t(4;14), t(14;16), and del(17p). other less common abnormalities associated with a worse prognosis include t(14;20) and ≥4 copies of 1q.: 1730–1 associated genetic mutations include atm, braf, ccnd1, dis3, fam46c, kras, nras and tp53. development the genetic and epigenetic changes occur progressively. the initial change, often involving one chromosome 14 translocation, establishes a clone of bone marrow plasma cells that causes the asymptomatic disorder mgus, which is a premalignant disorder characterized by increased numbers of plasma cells in the bone marrow or the circulation of a myeloma protein immunoglobulin. further genetic or epigenic changes produce a new clone of bone marrow plasma cells, usually descendant from the original clone, that causes the more serious, but still asymptomatic premalignant disorder smoldering multiple myeloma. this myeloma is characterized by a rise in the number of bone marrow plasma cells or levels of the circulating myeloma protein above that seen in mgus. subsequent genetic and epigenetic changes lead to a new, more aggressive clone of plasma cells, which cause further rises in the level of the circulating myeloma protein, further rises in the number of bone marrow plasma cells, or the development of one or more of a specific set of "crab" symptoms, which are the basis for diagnosing malignant multiple myeloma and treating the disease. in a small percentage of multiple myeloma cases, further genetic and epigenetic changes lead to the development of a plasma cell clone that moves from the bone marrow into the circulatory system, invades distant tissues, and thereby causes the most malignant of all plasma cell dyscrasias, plasma cell leukemia. thus, a fundamental genetic instability in plasma cells or their precursors leads to the progression: monoclonal gammopathy of undetermined significance → smoldering multiple myeloma → multiple myeloma → plasma cell leukemia being asymptomatic, monoclonal gammopathy of undetermined significance and smoldering multiple myeloma are typically diagnosed fortuitously by detecting a myeloma protein on serum protein electrophoresis tests done for other purposes. mgus is a relatively stable condition afflicting 3% of people aged 50 and 5% of people aged 70; it progresses to multiple myeloma at a rate of 0.5–1% cases per year; smoldering multiple myeloma does so at a rate of 10% per year for the first 5 years, but then falls off sharply to 3% per year for the next 5 years and thereafter to 1% per year. overall, some 2–4% of multiple myeloma cases eventually progress to plasma cell leukemia. diagnosis blood tests serum protein electropherogram showing a paraprotein (peak in the gamma zone) in a person with multiple myeloma the globulin level may be normal in established disease. a doctor may request protein electrophoresis of the blood and urine, which might show the presence of a paraprotein (monoclonal protein, or m protein) band, with or without reduction of the other (normal) immunoglobulins (known as immune paresis). one type of paraprotein is the bence jones protein, which is a urinary paraprotein composed of free light chains. quantitative measurements of the paraprotein are necessary to establish a diagnosis and to monitor the disease. the paraprotein is an abnormal immunoglobulin produced by the tumor clone. in theory, multiple myeloma can produce all classes of immunoglobulin, but igg paraproteins are most common, followed by iga and igm. igd and ige myeloma are very rare. in addition, light and or heavy chains (the building blocks of antibodies) may be secreted in isolation: κ- or λ-light chains or any of the five types of heavy chains (α-, γ-, δ-, ε- or μ-heavy chains). people without evidence of a monoclonal protein may have "nonsecretory" myeloma (not producing immunoglobulins); this represents about 3% of all people with multiple myeloma. additional findings may include a raised calcium level (when osteoclasts are breaking down bone, releasing it into the bloodstream), raised serum creatinine level due to reduced kidney function, which is mainly due to casts of paraprotein deposition in the kidney, although the cast may also contain complete immunoglobulins, tamm-horsfall protein and albumin. other useful laboratory tests include quantitative measurement of iga, igg, and igm to look for immune paresis, and beta-2 microglobulin, which provides prognostic information. on peripheral blood smear, the rouleaux formation of red blood cells is commonly seen, though this is not specific. the recent introduction of a commercial immunoassay for measurement of free light chains potentially offers an improvement in monitoring disease progression and response to treatment, particularly where the paraprotein is difficult to measure accurately by electrophoresis (for example in light chain myeloma, or where the paraprotein level is very low). initial research also suggests that measurement of free light chains may also be used, in conjunction with other markers, for assessment of the risk of progression from mgus to multiple myeloma. this assay, the serum free light chain assay, has recently been recommended by the international myeloma working group for the screening, diagnosis, prognosis, and monitoring of plasma cell dyscrasias. bone marrow aspirate showing the histologic correlate of multiple myeloma under the microscope, h&e stain plasmacytoma, h&e stain micrograph showing myeloma cast nephropathy in a kidney biopsy: hyaline casts are pas positive (dark pink/red – right of image). myelomatous casts are pas negative (pale pink – left of image), pas stain. atypical plasma cell infiltrate with both russell (cytoplasmic) and dutcher (nuclear) bodies (h&e, 50x) micrograph of a plasmacytoma, h&e stain histopathology a bone marrow biopsy is usually performed to estimate the percentage of bone marrow occupied by plasma cells. this percentage is used in the diagnostic criteria for myeloma. immunohistochemistry (staining particular cell types using antibodies against surface proteins) can detect plasma cells that express immunoglobulin in the cytoplasm and occasionally on the cell surface; myeloma cells are often cd56, cd38, cd138, and cd319 positive and cd19, cd20, and cd45 negative. flow cytometry is often used to establish the clonal nature of the plasma cells, which will generally express only kappa or lambda light chain. cytogenetics may also be performed in myeloma for prognostic purposes, including a myeloma-specific fluorescent in situ hybridization and virtual karyotype. the plasma cells seen in multiple myeloma have several possible morphologies. first, they could have the appearance of a normal plasma cell, a large cell two or three times the size of a peripheral lymphocyte. because they are actively producing antibodies, the golgi apparatus typically produces a light-colored area adjacent to the nucleus, called a perinuclear halo. the single nucleus (with inside a single nucleolus with vesicular nuclear chromatin) is eccentric, displaced by an abundant cytoplasm. other common morphologies seen, but which are not usual in normal plasma cells, include: bizarre cells, which are multinucleated mott cells, containing multiple clustered cytoplasmic droplets or other inclusions (sometimes confused with auer rods, commonly seen in myeloid blasts) flame cells, having a fiery red cytoplasm historically, the cd138 has been used to isolate myeloma cells for diagnostic purposes. however, this antigen disappears rapidly ex vivo. recently, however, the surface antigen cd319 (slamf7) was discovered to be considerably more stable and allows robust isolation of malignant plasma cells from delayed or even cryopreserved samples. the prognosis varies widely depending upon various risk factors. the mayo clinic has developed a risk-stratification model termed mayo stratification for myeloma and risk-adapted therapy (msmart), which divides people into high-risk and standard-risk categories. people with deletion of chromosome 13 or hypodiploidy by conventional cytogenetics, t(4;14), t(14;16), t(14;20) or 17p- by molecular genetic studies, or with a high plasma cell labeling index (3% or more) are considered to have high-risk myeloma. medical imaging the diagnostic examination of a person with suspected multiple myeloma typically includes a skeletal survey. this is a series of x-rays of the skull, axial skeleton, and proximal long bones. myeloma activity sometimes appears as "lytic lesions" (with local disappearance of normal bone due to resorption) or as "punched-out lesions" on the skull x-ray ("raindrop skull"). lesions may also be sclerotic, which is seen as radiodense. overall, the radiodensity of myeloma is between −30 and 120 hounsfield units (hu). magnetic resonance imaging is more sensitive than simple x-rays in the detection of lytic lesions, and may supersede a skeletal survey, especially when vertebral disease is suspected. occasionally, a ct scan is performed to measure the size of soft-tissue plasmacytomas. bone scans are typically not of any additional value in the workup of people with myeloma (no new bone formation; lytic lesions not well visualized on bone scan). x-ray of the forearm, with lytic lesions skull x-ray showing multiple lucencies due to multiple myeloma multiple myeloma in the upper arm pathological fracture of the lumbar spine due to multiple myeloma a ct of the brain revealed a lytic lesion in the left temporal bone (right side of image), and petrous temporal bones involving the mastoid segment of the facial nerve canal. red arrows: lesion; green arrow: normal contralateral facial nerve canal. the lesions are consistent with a myeloma deposit. ct scan of the lower vertebral column in a man with multiple myeloma, showing multiple osteoblastic lesions: these are more radiodense (brighter in this image) than the surrounding cancellous bone, in contrast to osteolytic lesions, which are less radiodense. femur with multiple myeloma lesions same femur before myeloma lesions for comparison humerus with multiple myeloma lesions same humerus before, with just subtle lesions diagnostic criteria in 2003, the img agreed on diagnostic criteria for symptomatic myeloma, asymptomatic myeloma, and mgus, which was subsequently updated in 2009: symptomatic myeloma (all three criteria must be met): clonal plasma cells >10% on bone marrow biopsy or (in any quantity) in a biopsy from other tissues (plasmacytoma) a monoclonal protein (myeloma protein) in either serum or urine and it has to be more than 3g/dl (except in cases of true nonsecretory myeloma) evidence of end-organ damage felt related to the plasma cell disorder (related organ or tissue impairment, crab): hypercalcemia (corrected calcium >2.75 mmol/l, >11 mg/dl) renal failure (kidney insufficiency) attributable to myeloma anemia (hemoglobin <10 g/dl) bone lesions (lytic lesions or osteoporosis with compression fractures) note: recurrent infections alone in a person who has none of the crab features is not sufficient to make the diagnosis of myeloma. people who lack crab features, but have evidence of amyloidosis, should be considered as amyloidosis and not myeloma. crab-like abnormalities are common with numerous diseases, and these abnormalities must be felt to be directly attributable to the related plasma cell disorder and every attempt made to rule out other underlying causes of anemia, kidney failure, etc. in 2014, the imwg updated their criteria further to include biomarkers of malignancy. these biomarkers are >60% clonal plasma cells, a serum involved / uninvolved free light chain ratio ≥ 100 (the concentration of the involved free light chain must be ≥ 100 mg/l) and more than one focal lesion ≥ 5 mm by mri. together, these biomarkers and the crab criteria are known as myeloma-defining events (mdes). a person must have >10 % clonal plasma cells and any mde to be diagnosed with myeloma. the biomarker criteria were added so that smouldering people with multiple myeloma at high risk of developing multiple myeloma could be diagnosed before organ damage occurred, so they would therefore have a better prognosis. asymptomatic/smoldering myeloma: serum m protein >30 g/l (3 g/dl) or clonal plasma cells >10% on bone marrow biopsy and no myeloma-related organ or tissue impairment monoclonal gammopathy of undetermined significance (mgus): serum paraprotein <30 g/l