Spinal extradural arachnoid cysts associated with distichiasis and lymphedema.

Spinal extradural arachnoid cysts (SEDAC) are lesions communicating to the subarachnoid space of the spinal canal via a dural defect. SEDAC occupies intraspinal space and sometimes causes neurological disturbances. Although most reported cases are sporadic, several familial cases have been described, suggesting a genetic etiology. Here we report on a family with SEDAC inherited in an autosomal dominant mode. Detailed study showed that the family has the lymphedema-distichiasis syndrome. Among family members examined, a total of ten in two generations manifested all or some of the following features: SEDAC, distichiasis and lymphedema. Seven had spinal cysts, four had both SEDAC and distichiasis, and one had SEDAC distichiasis and lymphedema; three did not have SEDAC. These findings, together with rarity of both distichiasis and lymphedema in the general population, support that all of the ten members were affected with one clinical entity, the lymphedema-distichiasis syndrome. The distribution of features illustrates the variable expressivity of clinical manifestations. Although FOXC2 mutation analysis was not performed in our family, it is likely that SEDAC is a component manifestation of lymphedema-distichiasis syndrome and more consistent in our family than those reported.