20 yr old man with progressive proptosis which increases on bending forward. It is compressible and has no bruit or thrill. USG showed "hyperintense" mass with shadowing of mass. The diagnosis is:

A i.e. Orbital varix Plexiform neurofibroma (exclusively associated with NF 1) presents in early childhood with periorbital swelling, diffuse involvement of orbit with disfiguring hyperophy of periocular tissue, S-shaped mechanical ptosis (d/t lid involvement). On palpation involved tissue feel like a bag of worms. Pulsation without a bruit & thrill (best detected on applantation tonometry)Q may be present if there is an associated congenital defect of greater wing of sphenoid. Other features of NF like Lisch (iris) nodules, prominent corneal nerves, optic nerve glioma, uveal NF may be present. Isolated neurofibroma (less common) presents in 3rd to 4th decade with insidious mildly painful proptosis unassociated with visual impairment or ocular motility dysfunction.