An ancient schwannoma misdiagnosed as a dermoid cyst on ultrasound examination: a case report

Abstract

Ancient schwannomas are benign, long-standing schwannomas of the neural sheaths. This schwannoma subtype is characterized by cystic and hemorrhagic changes. These degenerative changes are thought to result from the tumor’s long-term progression and have the potential to be misdiagnosed as other soft tissue tumors or sarcomas. A 37-year-old female patient presented to our department with discomfort caused by a mass on the anterior side of her forearm. Approximately 2 weeks prior to her visit, an excisional biopsy was attempted under local anesthesia, but the patient experienced severe tingling sensations up to the wrist during surgery, preventing successful removal of the mass. Ultrasonography and magnetic resonance imaging (MRI) were performed for further differential diagnosis. An excisional biopsy was performed under general anesthesia, and histologic analysis revealed typical degenerative features of ancient schwannoma. A thorough examination, including MRI, is necessary to identify these tumors, prevent potential misdiagnosis, and ensure appropriate treatment.