Background: Traumatic leptomeningeal cyst as a complication of skull fractures was initially thought to occur primarily in the pediatric population. The occurrence of a traumatic leptomeningeal cyst in the adult population is rare.
Case description: A lump in the right parietal region of this 53-year-old man prompted a computed tomography (CT) scan. The patient denied any symptoms and was in good health. Examination confirmed a firm, nontender, nonpulsatile mass in the right parietal region of the skull. The CT scan demonstrated a 4 x 3 cm area of irregular bone destruction involving both the inner and outer table of the skull. At operation a distinctly raised paper-thin outer table was noted, and underneath was a soft, tan-colored mass, which measured approximately 2 x 2 cm and was connected to the underlying brain through a 1 cm dural defect. The extradural portion of the mass was amputated, the dura repaired with a pericranium patch, the skull defect was repaired with a split thickness bone graft, and the final pathology was congruent with gliotic brain.
Conclusion: Although rare, this case demonstrates a traumatic leptomeningeal cyst in an adult.