Mast cells contribute to the angiogenesis in non-Hodgkin lymphoma. An immunohistochemical study based on the relationship with microvessel density.

Only few data are available in the literature concerning angiogenesis in hematological malignancies. Non-Hodgkin lymphoma classified on the base of molecular profile is frequently characterized by unpredictable behavior that seems to be related to tumor cells and also to the tumor microenvironment. The tumor microenvironment contains blood vessels and a large variety of cells that can play an important role to the progression of angiogenesis and tumor growth. From these, mast cells have been shown to be a source of angiogenic factors. The aim of this work was to investigated the relationships between mast cells and blood vessels in non-Hodgkin lymphoma and reactive lymphoid tissue from three different anatomical sites. Using double immunostaining method CD34/mast cell tryptase we noticed that mast cell density was significantly lower in the follicular lymphoma than in diffuse type lymphoma. The morphology of vessels, the presence of pillars and splitting suggested that intussusceptions is the main mechanism of angiogenesis. In the cases with primary lymphoma of the spleen, we found few mast cells and a high number of blood vessels. Our data suggest that lymphoma-associated angiogenesis is driven in part by the tumor microenvironment, and particularly, by mast cells. On the other hand, our results support the organ-specific tumor-associated angiogenesis in malignant non-Hodgkin lymphoma.