Dermoid cysts are classified into three types based on pathological cellular components: dermoid, epidermoid, and teratoid cysts. Teratoid cysts have skin appendages such as sweat glands, sebaceous glands and hair follicles, and additionally have cartilage, muscle, vascular, respiratory tissues and gastrointestinal tissues derived from mesoderm or endoderm. We describe an extremely rare case of a teratoid cyst around the mandibular angle. A 17-year-old woman was referred to our hospital because of a swelling around the left mandibular angle. Initial clinical examinations revealed a soft elastic mass that measured 45 × 45 mm. The lesion was preoperatively diagnosed as dermoid cysts or lipoma around the mandibular angle on computed tomography (CT) and magnetic resonance imaging (MRI). The lesion was removed and the histopathological diagnosis was a teratoid cyst containing squamous epithelium, sebaceous glands, hair follicles, sweat glands, arrector pili muscle, and cartilage. Recurrence has not occurred as of 6 years 6 months after surgery.
