["True" mixed pial-dural arteriovenous malformation: a case report].

Mixed pial-dural arteriovenous malformation(AVM) is currently defined as a malformation fed by both the pial and meningeal arteries. Although many cases of mixed pial-dural AVM have been reported, few papers have addressed its pathological locations. The authors report a case of a 43-year-old male patient with mixed pial-dural AVM in the occipital lobe, consisting of two distinct nidi located on the tentorium and in the cerebral parenchyma respectively. The lesions were surgically resected, and the pathological examination confirmed that both were indeed AVM. The authors discuss this rare type of AVM, focusing on the possible pathogenic mechanism thereof.