The formation of new blood vessels is a critical process for tumor growth and may be achieved through different mechanisms. Angiogenesis represents the first described and most studied mode of vessel formation, but tumors may also use alternative ways to secure blood supply and eventually acquire resistance to anti-angiogenic treatments. These non-angiogenic mechanisms have been described more recently and include intussusceptive microvascular growth (IMG), vascular co-option, and vasculogenic mimicry. Like solid tumors, also in lymphomas angiogenic and non-angiogenic pathways play a fundamental role in tumor growth and progression. In view of the relevant prognostic and therapeutic implications, a comprehensive understanding of these mechanisms is of paramount importance for improving the efficacy of treatment in patients with lymphoma. In this review, we summarize the current knowledge on angiogenic and non-angiogenic mechanisms involved in the formation of new blood vessels in Hodgkin’s and non-Hodgkin’s lymphomas.

Diffuse large B cell lymphoma (DLBCL) is the most common non-Hodgkin lymphoma (NHL), accounting for about 40% of all cases NHL. Analysis of the tumour microenvironment is an important aspect of the assessment of the progression of DLBCL. In this review article, we have analyzed the role of different cellular components of the tumour microenvironment, including mast cells, macrophages, lymphocytes, in tumour progression of DLBCL. We examined several approaches to confront the available pieces of evidence; three key points emerged. DLBCL is a disease of malignant B-cells spreading and accumulating both at nodal and in extranodal sites. Both in patients with nodal and extranodal lesions, the subsequent induction of a cancer-friendly environment appears pivotal. DLBCL cell interaction with mature stromal cells and vessels confers tumour protection and inhibition of immune response while delivering nutrients and oxygen supply. Single cells may also reside and survive in protected niches in the nodal and extranodal sites as a source for residual disease and relapse. This review aims to molecularly and functionally recapitulate the DLBCL-milieu crosstalk, to relate niche and pathological angiogenic constitution and interaction factors to DLBCL progression.