Prostatic acid phosphatase is a possible tumor marker for intravascular large B-cell lymphoma

Intravascular large B-cell lymphoma (LBCL) is a rare and aggressive subtype of diffuse LBCL characterized by disseminated intravascular proliferation of neoplastic lymphocytes. Obstruction of blood flow by tumor cells in a variety of organs can cause an array of clinical changes, including alteration of the neural and spinal system and the respiratory system, as well as skin lesions. It is usually very difficult to diagnose intravascular LBCL in a patient simply from clinical symptoms or laboratory examinations. We here document our findings that serum prostatic acid phosphatase levels in both males and a female (2.2-24.0 microg/L) reflect the presence of intravascular LBCL, changing synchronously in response to chemotherapy. To determine whether prostatic acid phosphatase (PAP) might be a useful tumor marker for early diagnosis, we reviewed five intravascular LBCLs. Immunohistochemically, tumor cells in all cases were positive for anti-PAP antibody. The results were further confirmed in one case by Western-blot analysis and in another by the detection of amplified messenger RNA for PAP in microdissected tumor cells, respectively. PAP has not been detected in 17 lymphomas (diffuse LBCL, 8 cases; follicular lymphoma, 3 cases; T-cell lymphoma, 3 cases; Hodgkin lymphoma, 3 cases) by Western blot analyses. We conclude that serum PAP is a useful tumor marker for intravascular LBCL and that it deserves further investigation in this context.