<prompt> The most commonly seen primary orbital tumour in children isOptic nerve sheath meningiomaRetinoblastomaRhabdomyosarcomaGlioma of optic nerve  <response>: Rhabdomyosarcoma It is a highly malignant tumour of the orbit arising from the extraocular muscles. It is the most common primary orbital tumour among children, usually occurring below the age of 15 years 90. Clinical features: It classically presents as rapidly progressive proptosis of sudden onset in a child of 7-8 years. Massive proptosis due to rhabdomyosarcoma located in the superonasal quadrant mimmicking acute inflammatory process. The clinical presentation mimics an inflammatory process. The tumour commonly involves the superionasal quadrant; but may invade any pa of the orbit. Ref:- A K KHURANA; pg num:-394 