Rudimentary meningocele: Remnant of a neural tube defect?

Background: Rudimentary meningocele, a malformation in which meningothelial elements are present in the skin and subcutaneous tissue, has been describ ed in the past, under a variety of different terms and has also been referr ed to as cutaneous meningioma. There has been debate as to whether rudiment ary meningocele is an atretic form of meningocele or results from growth of meningeal cells displaced along cutaneous nerves Objective:We reviewed the clinical, histological, and immunohistochemical c haracteristics of rudimentary meningocele in an attempt to assess the most likely pathologic mechanism for it. Design: Retrospective study. Setting: University hospitals. Patients:Thirteen children with rudimentary meningocele. Main Outcome Measures: Medical records were reviewed and histopathologic ex amination as well as immunohistochemistry studies were performed for each c ase. A panel of immunoperoxidase reagents (EMA, CD31, CD34, CD57, S-100, an d CAM 5.2) was used to assess lineage and to confirm the meningothelial nat ure of these lesions. Results: Recent evidence indicating a multisite closure of the neural tube in humans suggests that classic meningocele and rudimentary meningocele are on a continuous spectrum. Conclusion: Rudimentary meningocele seems to be a remnant of a neural tube defect in which abnormal attachment of the developing neural tube to skin ( comparable to that in classic meningocele) could explain the presence of ec topic meningeal tissue. In the majority of cases, no underlying bony defect or communication to the meninges could be detected. However, in light of t he probable pathogenesis, imaging studies to exclude any communication to t he central nervous system should precede any invasive evaluation or interve ntion.