Prostatic acid phosphatase: a possible diagnostic marker of intravascular large B-cell lymphoma.

BACKGROUND AND OBJECTIVE Intravascular large B-cell lymphoma (IVL) has been treated as fever of unknown origin (FUO), and many patients have been treated inadequately based on incorrect diagnoses. We previously cares for a patient with IVL who tested positive for prostatic acid phosphatase (PAP), a marker of prostate cancer. Since then, we have regularly examined this mather when IVL was suspected to investigate the usefulness of PAP as a diagnostic marker for IVL. We retrospectively evaluated the usefulness of PAP as diagnostic marker of IVL. DESIGN AND METHODS We reviewed the clinical courses of 5 patients with IVL (3 males, 2 females) in comparison with 23 controls with hematologic malignancies other than IVL. RESULTS Serum levels of PAP were elevated in all 5 patients with IVL and 2 of the 23 controls. The difference was statistically significant using a chi-squared test (p=0.0002). The sensitivity and specificity of PAP were 100% and 91%, respectively, in the diagnosis of IVL. Its serum levels were closely associated with disease status. INTERPRETATION AND CONCLUSIONS This study suggests that PAP might be a useful marker for the screening and assessment of disease activity and responses to the treatment of IVL.