Ruptured internal carotid artery aneurysm presenting as a sinonasal organized hematoma: conventional approach may endanger life.

Sinonasal organized hematoma (SOH) is an uncommon benign entity with locally aggressive behavior. The conventional approach is complete resection. This approach, however, can cause massive hemorrhage and mortality in our patient due to a ruptured internal carotid artery (ICA) aneurysm hidden inside the SOH. To the best of our knowledge, this is the first case of a huge SOH with skull base invasion caused by a hidden ICA aneurysm, which usually would not be large enough to result in a sinonasal mass lesion. This case suggests that the possibility of an aneurysm should always be considered if a SOH is suspected, especially when it is huge and close to the ICA. Surgical resection may not be the first therapeutic choice unless the differential cause of a hidden aneurysm can be excluded.