Plasma cell
POEMS syndrome (also known as Crow–Fukase syndrome, Takatsuki disease, or PEP syndrome) is a rare and complex medical syndrome that involves a combination of syndrome-defining signs and symptoms due to the dysfunction of multiple organs. The syndrome is associated with a plasma cell dyscrasia in almost 100% of cases, pathological overexpression of certain cytokines in &gt;95% of cases, and the lymphoproliferative disorder termed Castleman's disease in ~15% of cases. (Rare cases of POEMS have been associated with polyclonal rather than clonal plasma cells; these cases are not plasma cell dyscrasias but rather appear to be caused by the over-activity of non-malignant immune cell responses in chronic infections or autoimmune diseases.) POEMS is an acronym standing for the characteristic signs or symptoms of the syndrome: Polyneuropathy, Organomegaly, Endocrinopathy, Plasma cell disorder (typically, the plasma cell burden is low in POEMS patients), and Skin changes (e.g. hemangioma, hyperpigmentation). The syndrome is defined by the presence of; both of two major criteria, peripheral neuropathy and a clonal plasma cell dyscrasia (increased bone marrow plasma cells in ~67% of cases; ≥1 plasmacytoma in ~33% of cases); at least one other major criteria (Castleman's disease, sclerotic bone lesions, elevated serum levels of the cytokine VEGF); and at least one minor criterion (organomegaly, extravascular volume overload [e.g. ascites, edema, pleural effusion, and/or pericardial effusion], endocrinopathy [i.e. hypogonadism, defects in the hypothalamic–pituitary–adrenal axis], skin changes, papilledema, and/or hematological manifestations [i.e. thrombocytosis or polycythemia]). The monoclonal protein in POEMS patients is typically identified as IgA or IgG which in &gt;95% of cases contains a λ chain that is restricted to either of two members of the V lambda 1 subfamily viz., IGLV1-40*01 and IGLV1-44*01 (there are 29 other members in the V lambda family). That is, the myeloma protein in POEMS is almost invariably a clonal λ light chain variant. Deletion of chromosome 13 and chromosomal translocations but not increases in chromosome number have also been reported to occur in POEMS patients.