Mollaret's meningitis: cytopathologic analysis of fourteen cases.

Mollaret's meningitis (MM) is a rare disease of benign nature characterized by recurrent episodes of aseptic meningitis. Cerebrospinal fluid (CSF) examination remains the sole diagnostic modality. Eighteen CSF samples from 14 patients were studied along with the clinical data. Specimens were prepared by cytocentrifugation and Millipore filtration and were stained with Diff-Quik and Papanicolaou stains. Eight patients were men and six were women, with an age range of 17-74 yr (mean age 37 yr). Most common clinical presentation was recurrent episodes of headaches and photophobia followed by a sustained mild fever lasting 5-7 days. The CSF showed markedly increased cellularity with pleocytosis. The differential count showed predominant monocytosis ranging from 84% to 100% (mean 96). In our series, two patients had herpes simplex virus type 2 (HSV-2) DNA detected by polymerase chain reaction (PCR) in the CSF. The monocytes were seen predominantly singly, but three cases showed a strong tendency to aggregate in small groups. Phenotypically, these cells had bean-shaped bilobed nuclei as well as multiple deep nuclear clefts depicting the so-called "footprint" appearance. In four cases, multiple blunt-tipped cytoplasmic pseudopods were noted. Degenerated monocytes with the appearance of the so-called "ghost cells" were noted in one-half of the cases. Background cells were mostly small mature lymphocytes; however, one-half of cases showed a significant amount of plasma cells and/or polymorphonuclear leukocytes (PMNs). Lysed blood with hemosiderin-laden macrophages and numerous leptomeningeal cells were seen in two cases. CSF examination of MM presents a spectrum of cytomorphologic features. When interpreted in light of the appropriate clinical setting. the latter, although nonspecific, provides an accurate diagnosis. The differential diagnosis includes various degenerative, inflammatory/infectious, and lymphoproliferative disorders of the central nervous system. Copyright 2003 Wiley-Liss, Inc.