Coexistence of Extra-Axial Cavernous Malformation and Cerebellar Developmental Venous Anomaly in the Cerebellopontine Angle

BACKGROUND: The coexistence of cavernous malformations (CMs) and developmental venous anomalies (DVAs) in the cerebellopontine angle (CPA) is exceedingly rare. To the authors' knowledge, only one case of CPA CM with concurrence of a neighboring DVA has been reported to date. CASE DESCRIPTION: The authors presented such vascular malformations in a 36-year-old man with progressive CPA syndrome during the course of six weeks. Preoperative neuroimaging suggested the diagnosis of an extra-axial hemorrhagic lesion in the CPA cistern with a cerebellar DVA in the close vicinity. The lesion was totally removed with the DVA untouched and was confirmed to be extra-axial in intimate contact with only the VII-VIII complex and the draining veins of DVA. Pathology revealed a CM. The patient underwent partial improvement in neurological function postoperatively. The radiographic follow-up at one year revealed no recurrence. CONCLUSIONS: CMs should be considered in the differential diagnosis of any extra-axial hemorrhagic mass, especially with a DVA in the proximity. The coexistence of CM and DVA in CPA, although maybe just a coincidence, suggests the possibility of a new subtype of extra-axial CPA CM secondary to a preexisting DVA. A long-term follow-up is justified in discovering the potential mechanism and biology of such uncommon vascular malformations.