Angiotropic lymphoma, also known as intravascular lymphomatosis, is characterised by widespread intravascular proliferation of malignant lymphoid cells, usually without evidence of focal disease. A case of a 52 year old man referred for investigation of a two year history of pyrexia of unknown origin, skin rash and multiple organ failure is described. Angiotropic lymphoma was seen in gastric, colonic and skin biopsy specimens, and review of an earlier skin biopsy specimen showed similar morphological features. In contrast to previous cases which showed B or T cell differentiation, immunohistochemical examination was positive for histiocyte markers. Molecular studies showed no evidence of immunoglobulin heavy chain gene or T cell receptor gene rearrangement. The patient responded to combination chemotherapy, comprising cyclophosphamide, doxorubicin, etoposide, and prednisolone. This case highlights the fact that advanced lymphoma may be present without evidence of focal disease and that the diagnosis may be missed easily both clinically and histologically.