Abnormalities of chromosome 2p23 with expression of ALK1 and p80 occur in both inflammatory myofibroblastic tumor (IMT) and anaplastic large cell lymphoma.
Conversely, the 24 p80- ALCL cases, in which epithelial membrane antigen (EMA) and bcl-2 positivities were 33% and 55%, respectively, were heterogeneous and could be subdivided into five different categories, namely (a) 11 cases of HD-like ALCLs, (b) six cases of p80 common ALCL, (c) three cases of secondary ALCL, (d) two cases of primary cutaneous ALCL, and (e) two cases of primary classical ALCL that lackedp80 expression.
A high percentage of extracutaneous CD30+ anaplastic large cell lymphomas (nodal ALCL) carry a specific chromosomal translocation, t(2;5) (p23;q35), that results in abnormal expression of p80 NPM/ALK chimeric protein (p80).
When paraffin sections of 105 cases of ALCL were stained using the anti-p80 antibody, 30 were shown to be p80 positive Clinicopathological comparison between p80-positive and p80-negative ALCLs revealed that the p80-positive cases occurred in a much younger patient age group and that the patients showed a far better 5-year survival rate.
However, the highest percentage (23 of 26 cases; 88.5%) of P80 positive cases was found in children compared with 60% (18 of 30 cases) in adult ALCL (P < .05).