This genetic instability is due to a myriad of acquired abnormalities including gene mutations; single nucleotide polymorphisms; depletions and duplications of parts of a gene, larger portion of a chromosome, or even an entire arm of a chromosome; translocations, deletions, and duplications of entire chromosomes; and increases and decreases in the expression of intact genes due to, e.g. the methylation of gene promotors and various less direct effects. These genetic abnormalities effect the Wnt signaling pathway, regulation of the cell cycle, RNA metabolism, protein folding, and cadherin-related cell adherence to extracellular matrix. These effects in turn control plasma cell proliferation, survival, apoptosis, adhesion to bone marrow, genome stability, and secretion of monoclonal immunoglobulins.Secondary plasma cell leukemia (sPCL) results from the comparatively slow development of plasma cell/plasma cell precursor genetic abnormalities which initially create a clone of cells that cause the premalignant condition of monoclonal gammopathy of undetermined significance. In a very small percentage of these cases, the progressive development of further genetic abnormalities serially create a clone(s) of plasma cells that cause the more serious but still premalignant disorder of smoldering multiple myeloma, overt myeloma cancer, and ultimately sPCL. In contrast to sPCL, pPCL presents de novo with a broad range of genetic abnormalities. For example, advanced methods for examining the genome viz., whole-exome sequencing and gene expression profiling, have identified 166 non-silent gene variants per pPCL patient sample at the time of diagnosis.
Additionally, malignant retroperitoneal fibrosis less frequently displaces the ureters medially when compared to other causes of retroperitoneal fibrosis.On fludeoxyglucose (18F) (FDG) positron emission tomography (PET) scan, FDG accumulation is shown in the affected area.Although biopsy is not usually recommended, it is appropriate when malignancy or infection is suspected. Biopsy should also be done if the location of fibrosis is atypical or if there is an inadequate response to initial treatment. Treatment
In the absence of severe urinary tract obstruction (which generally requires surgery with omental wrapping), treatment is generally with glucocorticoids initially, followed by DMARDs either as steroid-sparing agents or if refractory on steroids. The selective estrogen receptor modulator tamoxifen has shown to improve the condition in various small trials, although the exact mechanism of its action remains unclear. References


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