<prompt> The most common malignant orbital tumor in children is:RhabdomyosarcomaCavernous HemangiomaALLAML  <response>: The most common malignant orbital tumour in children is Rhabdomyosarcoma. Rhabdomyosarcoma is the most common primary malignant orbital tumor in the pediatric age group. Ref: Head neck surgery - otolaryngology: Volume 2 - Page 1501; Recent Advances in Ophthalmology - Volume 9 - Page 48. 