<prompt> 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:Orbital varixAV malformationNeurofibromatosisOrbital encephalocele  <response>: 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 dt lid involvement. On palpation involved tissue feel like a bag of worms. Pulsation without a bruit thrill best detected on applantation tonometryQ 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. 