Venous Angioma

A venous angioma, also referred to as a "developmental venous anomaly" (DVA), a variation of normal.
Usually seen as a little cluster or may seen as single prominent vein.
Angioma on their own don't tend to cause any trouble, except very few (reported) exceptions of bleed, so should generally be left alone.
May be seen isolated or in association with cavernoma, when associated with cavernous malformations (cavernomas) tend to be troublesome, usually present with seizures.
Similar cases: Developmental venous anomaly