Cytoplasmic 5-Lipoxygenase Staining Is a Highly Sensitive Marker of Human Tumors of the Choroid Plexus.

OBJECTIVES

To determine the immunoreactivity status of 5-lipoxygenase (5-LO) in normal tissues, in tumors of the human choroid plexus, and in other brain tumors.

METHODS

In total, 135 cases of various types of brain tumors were selected. Tissue samples were immunostained with a rabbit polyclonal anti-5-LO antibody.

RESULTS

Nuclear reactivity was observed in most brain tumors, with most of the positive tumor cells exhibiting low-level reactivity. Cytoplasmic strong immunoreactivity for 5-LO (2+ or 3+) was only observed in 8.8% of astrocytic tumors, 0% of oligodendrogliomatous tumors, 5.6% of ependymal tumors, 0% of embryonal tumors, 3.1% of meningeal tumors, and 0% of metastatic lung adenocarcinomas. In contrast, cytoplasmic immunoreactivity for 5-LO was detected in all 27 cases of choroid plexus tumors. Twenty-five cases showed strong and diffuse cytoplasmic immunoreactivity.

CONCLUSIONS

Our findings indicate that cytoplasmic 5-LO immunoreactivity is highly characteristic of human choroid plexus tumors but not other central nervous system tumor types. Cytoplasmic staining for 5-LO may prove to be a useful immunoreactive marker in the diagnosis of choroid plexus tumors.