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BackgroundCombined hepatocellular and cholangiocarcinoma (CHC) is a unique subtype of liver cancer comprising both hepatocellular carcinoma (HCC) and intrahepatic cholangiocarcinoma (ICC); however, its cellular origin remains unclear. The purpose of this study was to investigate the clinicopathologic features and the clonal relationship between HCC and ICC in 34 patients with CHC.MethodsThe clinicopathologic features and prognosis of the 34 CHC patients were compared with those of 29 patients with separated HCC and ICC (SHC). Loss of heterozygosity (LOH) at 10 highly polymorphic microsatellite markers was detected in 16 CHC and 10 SHC tissues for determination of the clonal origin of CHC. Expression of hepatocyte markers [hepatocyte paraffin 1 (Hep Par 1) and glypican 3 (GPC3)] and cholangiocyte markers [cytokeratin (CK)7 and 19] in tumor tissues was examined by immuno histochemical analysis.ResultsIn the 16 CHC specimens, the difference in LOH patterns between HCC and ICC was less than 30%, suggesting the same clonal origin of HCC and ICC. Consistent with this finding, immunohistochemical analysis revealed that hepatocyte markers (Hep Par 1 and GPC3) and cholangiocyte markers (CK7 and CK19) were simultaneously expressed in both the HCC and ICC components in 52.9% of CHC specimens, suggesting that the two components shared a similar phenotype with hepatic progenitor cells (HPCs). On the contrary, in all 10 SHC cases, the difference in LOH patterns between the HCC and ICC components was greater than 30%, suggesting different clonal origins of HCC and ICC. Overall survival and disease-free survival were shorter for patients with CHC than for patients with SHC (P < 0.05).ConclusionsOur results suggest that the HCC and ICC components of CHC may originate from the same clone, having the potential for dual-directional differentiation similar to HPCs. CHC tended to exhibit the biological behaviors of both HCC and ICC, which may enhance the infiltrative capacity of tumor cells, leading to poor clinical outcomes for patients with CHC.

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Clinicopathological and molecular features of indolent natural killer-cell lymphoproliferative disorder of the gastrointestinal tractAims: Indolent natural killer (NK) cell lymphoproliferative disorder of the gastrointestinal (GI) tract (iNKLPD) is a rare, recently recognised neoplasm. Most of the reported tumours are confined to the GI tract, while a small subset of the tumours harbour JAK3 mutations. We collected four cases of iNKLPD with the goal of adding additional information to the current knowledge of this disease regarding the clinicopathological, immunohistochemical and molecular features. Methods and results: Similar features including medium-to large-sized lymphoid cells with variable amounts of pale or slightly eosinophilic cytoplasm, and no evidence of EBER, TCR rearrangement were found in four cases. JAK3 K563_C565del mutation was found in one of three cases that were subjected to targeted next-generation sequencing. Unique findings of our study include one iNKLPD encountered for the first time in nasopharynx, where lesions could be inadvertently diagnosed as extranodal NK/T cell lymphoma, and one iNKLPD located in the gallbladder extended deeply into muscular and adventitial layers. Exceptional CD8-positive expression was observed in one iNKLPD. In addition, positive staining of phospho-STAT5, phospho-STAT3 and phospho-p38 were found in our cases. None of the four patients received therapy for lymphoma, but all had a benign clinical outcome during a follow-up time of 20-99 months. Conclusions: We present four iNKLPDs with clinical, immunohistochemical and molecular features similar to the reported cases, as well as some unusual characters, which expand our knowledge on this disease, and further support the neoplastic nature of iNKLPDs.

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Diffuse large B-cell lymphoma (DLBCL) is a group of heterogeneous tumors with different molecular traits and clinical features. MYD88 is an oncogene that activates the nuclear factor κB pathway in DLBCL. MYD88 L265P mutation frequently occurs in DLBCL with poor prognosis, while the clinical significance of non-L265P mutations needs to be clarified. Next-generation sequencing was performed on a cohort of 356 patients with DLBCL to investigate the impact of MYD88 mutation. Ten MYD88 mutated variants were detected in 32% (114/356) of the cases. V217F, S219C, S222R, M232T, S243N, and T294P were identified as pathogenic variants. MYD88 non-L265P mutations occurred less than L265P mutation in DLBCL of the central nervous system and breast tissue. The coexistence of MYD88 non-L265P mutations with PIM1 mutation was also less than that of L265P mutation. The progression-free survival in patients with DLBCL with MYD88 non-L265P mutation was statistically better than in patients with MYD88 L265P mutation. The interpretation of variants of MYD88 mutation offers a precise guide for the management of DLBCL.