MedGen

A rare vascular tumor characterized by a malignant space-occupying lesion composed of cells variably recapitulating features of normal endothelium. It mostly develops as a cutaneous tumor and is much less frequently located in the deep soft tissue. Clinical presentation is an enlarging mass, sometimes with symptoms like coagulopathy, anemia, persistent hematoma, or bruisability. Some tumors are associated with pre-existing conditions, e. g. Klippel-Trenaunay syndrome, Maffucci syndrome, or following radiation, among others. Older age, retroperitoneal location, large size, and high mitotic activity are predictors for poor outcome. [from ORDO]

L1 syndrome involves a phenotypic spectrum ranging from severe to mild and includes three clinical phenotypes: X-linked hydrocephalus with stenosis of the aqueduct of Sylvius (HSAS). MASA (mental retardation [intellectual disability], aphasia [delayed speech], spastic paraplegia [shuffling gait], adducted thumbs) syndrome including X-linked complicated hereditary spastic paraplegia type 1. X-linked complicated corpus callosum agenesis. Males with HSAS are born with severe hydrocephalus, adducted thumbs, and spasticity; intellectual disability is severe. In less severely affected males, hydrocephalus may be subclinically present and documented only because of developmental delay; intellectual disability ranges from mild (IQ: 50-70) to moderate (IQ: 30-50). It is important to note that all phenotypes can be observed in affected individuals within the same family. [from GeneReviews]