Cavernous Malformations to Be Investigated for Familiarity: The Role of Ki67 MIB1

Background: Familial forms of cavernous malformations (CMs) often occur as multiple lesions. Nevertheless, the presence of a single CM does not exclude the familiarity. The aim of this study is to establish which patients who undergo surgery for a single cerebral cavernous malformation (CCM), with no family history at initial diagnosis, should be investigated for familiarity through genetic testing and counseling.

Methods: Eight families with 2 or more members affected by CCM have been studied. A control group of sporadic cases operated on, with no family history and followed up 10 years or more, was also included. Analyzed factors were patient age and sex, location, number and size of the lesions, associated developmental venous anomaly, presence of epileptic seizures, symptomatic hemorrhage, focal neurological deficits, and documented growth of the malformation and Ki67 MIB1 proliferation index.

Results: The familial group of CCMs showed higher incidence of pediatric patients (P = 0.01), more frequent occurrence of multiple lesions (P = 0.0004), higher rate of large CCMs, and symptomatic hemorrhage; besides, all 3 cases with documented growth belonged to the familial group (14%). The expression of Ki67 MIB1 was positive in 79% of the familial cases versus 0% in the sporadic ones (P < 0.00001).

Conclusions: Patients with CCM and no known family history at the time of the initial diagnosis who present specific features should be studied by genetic screening. The Ki67 MIB1 is a useful biomarker in favor of familial occurrence and may be studied in all patients with CMs to define the indication to the genetic tests.