A Case Report of Cholesterol Granuloma in Mastoid Cavity

Cholesterol granulomas are benign granulomatous lesions caused by a tissue reaction to a foreign body. Lesion formation is caused by cholesterol crystals and occurs secondary to insufficient ventilation, drainage disorder, haemorrhage, and/or chronic inflammation. Cholesterol granulomas may involve the middle ear, the mastoid bone, and the petrous apex. However, cholesterol granulomas presenting as a mass obstructing the external ear canal are relatively rare and can be a diagnostic challenge, especially in a post-mastoidectomy case. We report a case of cholesterol granuloma occupying the roof of the mastoid cavity and presenting as a mass in the external auditory canal (EAC). Temporal bone computed tomography showed a soft tissue mass along the roof of the mastoid cavity with rarefaction of the tegmen mastoideum/roof of the mastoid air cells. The cholesterol granuloma was removed surgically, and characteristic pathological findings confirmed the diagnosis.