alk+ large b-cell lymphoma alk+ large b-cell lymphoma alk+ large b-cell lymphoma is a type of lymphoma.: 378 it was first reported in 1997.: 378 it is a rare, aggressive large b-cell process that shows alk expression.: 378 it is distinct from anaplastic large cell lymphoma, a t-cell lymphoma.: 564 signs and symptoms pathophysiology upregulation of alk is mainly due to chromosomal translocation t(2;17), resulting in a fusion gene of cltc with alk, but can rarely be due to t(2;5), fusing npm1 with alk;: 378 the later is the usual finding in anaplastic large cell lymphoma (alcl). the t(2;17) translocation occurs in less than 1% of cases of alk+ alcl, but has been identified in inflammatory myofibroblastic tumors. there is no association with epstein–barr virus: 378 or hhv8, or immunosuppression.: 378 the cells are cd20 and cd30 negative,: 306 showing weak focal expression in 3% and 6% respectively.: 378 they are ema and cd138 positive,: 306 showing 100% expression respectively.: 378 diagnosis the median age of diagnosis is approximately late thirties to early forties.: 378 the estimates of childhood disease vary (8%, 15%, 30%: 378 ) but it can be seen at any age.: 306 the disease usually arises in lymph nodes, particularly the neck, but extranodal involvement, including in the gastrointestinal tract, nasal cavity, ovary and brain, has been described. morphologically, there are large immunoblast-like cells with large central nucleoli, often cellular clusters, with a predilection for the lymph node sinuses: 378 : 306 in a cohesive pattern that can suggest carcinoma cells.: 378 : 306 treatment multiagent chemotherapy is given, and can result in long-term success, particularly in childhood: 306 but prognosis is generally poor,: 378 particularly in higher stage disease.