A comparison of polymerase chain reaction examination of cerebrospinal fluid and conventional cytology in the diagnosis of lymphomatous meningitis.

BACKGROUND

Inherent limitations of conventional cytology often result in a failure to diagnose lymphomatous meningitis in cerebrospinal fluid (CSF) specimens from patients who actually have the disease. The development of polymerase chain reaction (PCR) techniques for the diagnosis of lymphoma based on the detection of clonal rearrangements of the immunoglobulin or T-cell receptor genes offers an alternative, DNA-based test for the diagnosis of lymphoma in the CSF.

METHODS

In this retrospective study, 31 CSF specimens from 21 patients were examined by a PCR technique that can detect clonal immunoglobulin gene rearrangements. Twenty-four of the specimens came from 14 patients who eventually had definitive histologic or cytologic diagnoses of B-cell lymphoma. The other seven patients had other neurologic diagnoses, including two patients with reactive lymphocytosis, three with glioblastoma, one with metastatic carcinoma, and one with multi-infarct dementia. The results of the PCR examinations were compared with cytologic evaluation of the same CSF specimens.

RESULTS

Five of seven specimens from patients with central nervous system lymphoma that were suspicious for, but not diagnostic of, lymphoma by conventional cytology were positive by PCR. Of 13 specimens from patients with lymphoma that showed no cytologic evidence of malignancy, 5 were positive by PCR. Two of four specimens for which conventional cytology showed definitive evidence of lymphoma were positive by PCR. Two specimens from patients with a reactive lymphocytosis showed a polyclonal pattern by PCR. Specimens from patients with other neurologic diseases were negative by PCR even when cytologically malignant (glioblastoma) cells were present in the specimen.

CONCLUSIONS

PCR examination of CSF is practical, complements conventional cytology, and sometimes provides the correct diagnosis when conventional cytology yields only ambiguous results.