Interdural hematomas are primarily observed in infants, and adult interdural hematomas are rare. We describe a 54-year-old woman with a round, well-defined mass. The mass was an interdural hematoma that was misdiagnosed as an epidural hematoma. Unlike an epidural hematoma, interdural hematomas are located between the two layers of the dura mater, and the dural tail sign can be observed.
Keywords: epidermoid cyst; epidural hematoma; extra axial tumor; interdural hematoma.