Vacuolated cells in neurofibroma: an immunohistochemical study

BACKGROUND: Vacuolated cells could be encountered in neurofibroma. OBJECTIVES: Frequency and immunohistochemical feature of vacuolated cells in neurofibroma. METHODS: Sixty-two lesions of neurofibroma including five plexiform neurofibromas were re-evaluated for the search of vacuolated cells. Immunohistochemical analysis was performed for cases with vacuolated cells. RESULTS: In five cases of plexiform neurofibroma and four cases of sporadic neurofibroma with endoneurial component, presence of vacuolated cells in the endoneurial mucoid area was noted. They were immunoreactive both with S-100 protein and CD34, mostly negative for factor XIIIa and negative for epithelial membrane antigen. Vacuolated cells were found neither in the diffuse portion of plexiform neurofibroma nor in sporadic diffuse neurofibroma. CONCLUSION: Presence of vacuolated cells is a highly characteristic feature of endoneurial portion of neurofibroma. Considering immunoreactivity both with S-100 protein and CD34 in the majority of vacuolated cells, they could be regarded as to represent endoneurial precursor cells in a certain stage of differentiation to Schwann cells.