Cavernous malformation within a schwannoma: review of the literature and hypothesis of a common genetic etiology.

The finding of cavernous malformations within tumors of the central or peripheral nervous system is a rare occurrence. We report a case of a histologically proven cavernous malformation found within an eighth cranial nerve schwannoma in a 76-year-old man. The patient presented with progressive loss of hearing on the left, facial pain and dysesthesia. Symptoms improved significantly after the tumor was subtotally resected through a left retrosigmoid craniotomy. Including the present report, 34 cases of cavernous malformations associated with tumors of nervous system origin, 24 cases (71%) involving tumors of Schwann cell origin, and 9 cases (26%) involving gliomas have been published. The cases were classified into two forms based on the type of association. Conjoined association, in which the cavernous malformation is located within the tissue of the nervous system tumor, and discrete association, in which the cavernous malformation and nervous system tumor are in separate locations. We explore the etiology of this association and hypothesize that a common genetic pathway may be involved in a majority of these cases.