OBJECTIVE: This is a presentation of a seemingly new otolaryngologic disease. SETTING: This study was conducted at a tertiary referral center. CASE REPORT: A 38-year-old healthy man developed left-sided sudden deafness with vertigo and temporary left facial palsy. A granulating and destructive lesion in the left temporal bone was discovered; repeated histologic examination only showed simple granulation tissue. After 6 months, a part of the bony cochlea was extruded. With approximately 8 months' delay and after the patient had had postoperative lung embolism, plasma homocysteine was found to be significantly elevated, a condition known as an independent risk factor for thromboembolic lesions. In the acquired form, it is most often caused by nutritional deficiency of vitamin B cofactors. Accordingly, the patient was treated with folic acid, which rapidly normalized plasma homocysteine. Subsequently, the granulation tissue in the temporal bone gradually disappeared, clinically and radiologically, and the lesion healed, obviously without cochlea function. CONCLUSIONS: Thromboembolic lesion in the left temporal bone, probably in the thin end artery a. labyrintina, i.e., an avascular osteonecrosis. During the latest years, an association between avascular osteonecrosis (most often in the hip) and conditions with increased risk of thrombosis such as hyperhomocystinemia has been established but, to the best of our knowledge, it is never with a lesion in the temporal bone.