dermoids

Dermoids, or dermoid cysts, are benign developmental lesions that arise from ectodermal tissue. They are a type of mature cystic teratoma and may contain skin-like tissue such as hair, sebum, and sweat glands, and occasionally teeth or other tissue. Histologically they are lined by stratified squamous epithelium and may contain skin appendages; by contrast, epidermoid cysts are lined by squamous epithelium without adnexal structures.

Dermoids most commonly occur in the head and neck (especially periorbital and middle cranial fossa regions) and in the ovaries, where they are known as mature cystic teratomas. They may also be found intracranially, intraspinally, or along surgical scars, as well as in other midline locations.

Pathogenesis is typically congenital, stemming from trapping of ectodermal tissue during embryonic development. They are usually benign, but rare malignant transformation can occur in ovarian dermoids, especially in postmenopausal patients.

Clinical features vary by location. Ovarian dermoids often present as an incidental pelvic mass or may cause abdominal pain or torsion. Orbital and cranial dermoids present as slow-growing masses; rupture can lead to inflammation or chemical meningitis if intracranial.

Imaging aids diagnosis. Ultrasound of ovarian lesions may show a complex cyst with echogenic material; CT can reveal fat density and calcifications; MRI characterizes fat signal and relation to surrounding structures. Management is surgical excision; ovarian lesions are typically managed with cystectomy to preserve ovarian tissue when feasible. Prognosis is favorable with complete removal; recurrence is uncommon but possible if resection is incomplete.