DLBCL, NOS represents 80–85% of all DLBCL. The remaining DLBCL cases consist of relatively rare subtypes that are distinguished by their morphology, (i.e. microscopic appearance), immunophenotype, (i.e. expression of certain marker proteins), clinical findings, and/or association with certain pathogenic viruses. Some cases of DLBCL, NOS, while not included in the 2016 World Health Organizations classification, are clearly associated with, and caused by, chronic infection by the bacterium, Helicobacter pylori. Diffuse large B-cell lymphoma, not otherwise specified
DLBCL cases that do not fit the distinctive clinical presentation, tissue morphology, neoplastic cell phenotype, and/or pathogen-associated criteria of other DLBCL subtypes are termed Diffuse large B-cell lymphoma, not otherwise specified: DLBCL, NOS, while representing 80–85% of all DLBCL cases, is a diagnosis of exclusion. In general, DLBCL, NOS is an aggressive disease with an overall long-term survival rate in patients treated with standard chemotherapy regimens of ~65%. However, this disease has many variants that differ not only in the just cited parameters but also in their aggressiveness and responsiveness to treatment. Presenting signs and symptoms
About 70% of DLBCL, NOS cases present primarily with lymph node disease. In these cases, the most typical presenting symptom at the time of diagnosis is a mass that is rapidly enlarging and located in a part of the body with multiple lymph nodes such as the groin, arm pits, or neck.
By extrapolating the number of expected identical twins (about one-third) from annual multiple births, and the number of twins with monochorionic placentae (about two-thirds), and from these the number thought to develop TTTS (about 15%), there are at least 4,500 TTTS cases per year in the U.S. alone: 139,816 × .33 × .66 × .15 = 4,568 cases of TTTS per year in U.S. (involving more than 9,000 babies.) Since spontaneous pregnancy losses and terminations that occur prior to 20 weeks go uncounted by the C.D.C., this estimate of TTTS cases may be very conservative. Although infertility treatments have increased the rate of multiple birth, they have not appreciably diluted the expected incidence of identical twins. Studies show a higher rate of identical twins (up to 20 times with IVF) using these treatments versus spontaneous pregnancy rates. One Australian study, however, noted an occurrence of only 1 in 4,170 pregnancies, or 1 in 58 twin gestations. This distinction could be partly explained by the "hidden mortality" associated with MC multifetal pregnancies—instances lost due to premature rupture of membrane (PROM) or intrauterine fetal demise before a thorough diagnosis of TTTS can be made. History
TTTS was first described by a German obstetrician, Friedrich Schatz, in 1875. Once defined by neonatal parameters—differences in birth weight and cord hemoglobin at the time of delivery—TTTS is now defined differently. Today, it is known that discordant fetal weights will most likely be a late manifestation, and fetal hemoglobin through cordocentesis is often equivalent in the twin pair even in severe TTTS.