The differential diagnosis can be stratified along either the clinical or radiological findings. The findings of painful proptosis with lid prominence temporally are suggestive of a ruptured dermoid cyst or dacryoadenitis. A lymphangioma with hemorrhage could present in a similar fashion but would tend to be more sudden in onset with skin discoloration. Orbital pseudotumor or granulocytic sarcoma are other possibilities. The discovery of bony erosion on CT raises the question of a malignant process. A metastatic tumor, rhabdomyosarcoma, or adenoid cystic carcinoma are compatible with these findings. Eosinophilic granuloma or aneurysmal bone cyst could present in similar fashion. An orbital abscess could presumably induce an osteomyelitis with bony changes as well. The bony erosion makes some clinical possibilities such as orbital pseudotumor or dacryoadenitis less likely.