The pseudomeningocoele that wasn't: case report of an adult who presented with a late infection of an implant.

This case report describes an unusual case of a 55-year-old male, who presented with what appeared to be a pseudomeningocoele. The patient suffered a skull fracture secondary to a direct blow almost 30 years prior, and had been repaired with a calvarial implant at that time. He had been symptom free for most of that time, until he presented to our institution with a bulging cyst in his left frontal region. Computed tomography revealed a calvarial defect at the site of the cyst and a presumptive diagnosis of pseudomeningocoele was made. As part of his treatment, the patient underwent a lumbar puncture and lumbar peritoneal shunt. These procedures, although temporarily beneficial, ultimately proved unsuccessful in permanently decreasing the size of the cyst. After all conservative measures were exhausted, the team surgically explored the patient: while no communication between the cerebrospinal fluid and cyst could be found, which would be expected in a pseudomeningocoele, there was fibrinous exudates on the implant surface. Tissue cultures showed Staphylococcus epidermidis. This case emphasises the importance of surgical exploration to make a correct diagnosis, as in this case of a sub-clinical calvarial implant infection 30 years after insertion of the implant.