Cryptic fibromuscular dysplasia in the meningeal vessels. An autopsy study.

We retrospectively evaluate the presence of cryptic fibromuscular dysplasia (FMD) (i.e. not macroscopically visible and not associated to FMD in larger arteries) in the small meningeal vessels in a comprehensive series of patients. Such a study has not been performed before to our knowledge. The meningeal tissue has been systematically examined in a series of 100 consecutive autopsies. The immunohistochemical study was performed in one case with leptomeningeal FMD. In the whole series only one case had FMD in the small leptomeningeal arteries. The histological variant was intimal fibroplasia, a rare variant of FMD. Immunohistochemistry was necessary to confirm this peculiar change of the vascular wall. Cryptic fibromuscular dysplasia in the meninges is a very rare finding in our series of autopsied patients--1% of cases, in concordance with the literature data. The clinical associations of this lesion are difficult to be related to this lesion. A cryptic presence of FMD must be suspected in some cases with stroke.