Angiotropic lymphoma is a rare, aggressive, intravascular non-Hodgkin's lymphoma, usually of B-cell phenotype. Because lymphoma is often clinically unsuspected, the small skin or muscle biopsies typically obtained for evaluation make assessment of lymphoid clonality through cell surface markers or Southern blot hybridization analysis difficult or impossible. The recent development of polymerase chain reaction methodologies to detect chromosomal translocations and immunoglobulin heavy chain gene rearrangement on paraffin-embedded tissue offers an attractive alternative for ascertaining the clonality of lymphoproliferative processes. We report a case of B-cell angiotropic lymphoma in which a monoclonal variable diversity joining region rearrangement of the immunoglobulin heavy chain locus was detected by polymerase chain reaction in both ante- and postmortem, formalin-fixed, paraffin-embedded skeletal muscle. The use of polymerase chain reaction in assessing clonality in angiotropic lymphoma is enhanced by the general absence of a background of reactive B-lymphoid cells in angiotropic lymphoma, which can obscure the monoclonal band and/or compromise sensitivity. No amplification product was obtained for t(14;18) involving the bcl-2 major breakpoint region. It is interesting to note that this case exhibited rare circulating lymphoma cells and more extensive bone marrow involvement (more than 100 tumor cells/high magnification field) than has been previously described.