Intravascular large B-cell lymphoma: a chameleon with multiple faces and many masks.

Intravascular large B-cell lymphoma (IVLBCL) is a rare, clinically aggressive lymphoma entity characterized by an almost exclusive growth of large cells within the lumen of all sized blood vessels. The reasons for this peculiar localization of neoplastic cells are only partially understood. Clinically, in its classical variant, IVLBCL presents with many nonspecific signs and symptoms such as fever of unknown origin and involvement of the central nervous system and skin. Cases, which show disease limited to the skin, following extensive staging workup, are called cutaneous variants and show a better prognosis. In addition, a hemophagocytic variant associated with hemophagocytic syndrome and often with hepatosplenic involvement and cytopenia has been described. The classical and hemophagocytic variants are present mainly in western or Asian countries, respectively, although exceptions have been increasingly reported in both geographical areas. The cutaneous variant is mostly observed in western countries. Staging of IVLBCL is difficult and still not satisfactory. The often poor prognosis of this type of lymphoma has been substantially improved by immunochemotherapy, in particular with rituximab. Despite improved outcome, a significant proportion of patients relapse, in particular those with central nervous system manifestations. This review focuses on histopathological features, pathogenetic elements, presenting symptoms, clinical variants, disease progression, prognostic factors, therapeutic management, and the outcome of IVLBCL.