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Cells and multicellular structures can mechanically align and concentrate fibers in their ECM environment and can sense and respond to mechanical cues by differentiating, branching, or disorganizing. Here we show that mammary acini with compromised structural integrity can interconnect by forming long collagen lines. These collagen lines then coordinate and accelerate transition to an invasive phenotype. Interacting acini begin to disorganize within 12.5 ± 4.7 h in a spatially coordinated manner, whereas acini that do not interact mechanically with other acini disorganize more slowly (in 21.8 ± 4.1 h) and to a lesser extent (P < 0.0001). When the directed mechanical connections between acini were cut with a laser, the acini reverted to a slowly disorganizing phenotype. When acini were fully mechanically isolated from other acini and also from the bulk gel by box-cuts with a side length <900 μm, transition to an invasive phenotype was blocked in 20 of 20 experiments, regardless of waiting time. Thus, pairs or groups of mammary acini can interact mechanically over long distances through the collagen matrix, and these directed mechanical interactions facilitate transition to an invasive phenotype., Engineering and Applied Sciences, Version of Record

By literature review, plasmacytomas arising in immunocompetent patients are rarely associated with Epstein-Barr virus (EBV) infection. EBV-positive plasmacytoma can cause a diagnostic dilemma as it may morphologically and phenotypically overlap with a clinically aggressive plasmablastic lymphoma (PBL). We reported the clinicopathologic and immunophenotypic findings of four patients with EBV-positive plasmacytomas (three cases of extramedullary plasmacytomas, one case of solitary plasmacytoma of bone) with immunocompetent status. These tumors were characterized by a diffuse proliferation of mature appearing plasma cells, which were diffusely positive for EBV encoded RNA (EBER) by in situ hybridization. All the four patients were alive with no evidence of disease at last follow-up., Competing Interests: None., (IJCEP Copyright © 2020.)