The article describes the following case: a 63-year-old patient with sarcoidosis, who was on long-term therapy with metipred, developed profuse epistaxis, and upon admission to the hospital, clinical manifestation of stroke. Computer tomography (CT) of the brain at admission revealed destruction of the posterior wall of the sphenoid bone and an area of increased density in the projection of the left optic nerve regarded as a neoplasm of the sphenoid sinus or inflammatory changes. CT angiography revealed the occlusion of the left internal carotid artery (LICA) from the C1 segment throughout. At the time of thrombus extraction, the patient developed profuse bleeding from the nasal cavity. According to staged angiography, the antegrade blood flow through the LICA to the sphenoid segment was restored; against the background of profuse bleeding, the flow of contrast from the LICA into the sphenoid sinus and further into the nasopharynx is visualized; in the projection of the sphenoid sinus, a formation was revealed that required differentiation between a giant aneurysm, an arteriovenous fistula, and a neoplasm of the sphenoid sinus. Destructive embolization of the LICA at the level of the petrosal segment was performed for vital indications, the bleeding was stopped, but the patient died due to acute posthemorrhagic anemia. An autopsy revealed a mycotic aneurysm of the LICA, the rupture of the wall of which caused nasal bleeding, which was spontaneously stopped due to the formation of an extended thrombus, which, in turn, became the cause of stroke.