Bilateral proptosis is common in
C i.e. A-V communications Cavernous hemangioma, capillary hemangioma, dermoid cyst, rhabdomyosarcoma, fibrous histiocytoma, and orbital cellulitisQ mostly cause unilateral proptosis. AV communications eg carotid - cavernous fistula are usually unilateral but may become bilateral (contralateral) alsoQ.
Cavernous hemangioma
Rhabdomyosarcoma
A-V communications
Orbital cellulitis