Dermoid

Dermoid refers to a type of lesion that resembles skin and contains skin-like tissue. In medical usage, dermoid lesions arise from ectodermal elements and are often developmental inclusion cysts. The term is used for several related conditions, including dermoid cysts and mature teratomas, and may appear in various body sites along the midline or in glands and skin.

Dermoid cysts are benign cystic lesions lined by stratified squamous epithelium and commonly containing skin adnexa such as hair follicles, sebaceous glands, and sometimes teeth or fat. They can occur in the ovaries (where they are typically called mature cystic teratomas), the skin and subcutaneous tissues, or intracranial and orbital regions. Ovarian dermoid cysts often present in women of reproductive age and may cause abdominal pain or mass effect; orbital dermoids commonly present as slow-growing, painless lids or eyebrow masses.

Diagnosis relies on imaging and histology. Ultrasound, CT, and MRI help characterize the contents and relationships to surrounding structures, while histologic examination confirms the diagnosis by demonstrating epidermal lining with adnexal structures. Treatment is usually surgical removal with the goal of complete excision to minimize recurrence. Special care is taken to avoid spillage of cyst contents, which can cause chemical irritation or peritonitis in abdominal cases.

Prognosis is generally excellent for benign dermoid cysts. Malignant transformation is rare but reported, particularly in ovarian dermoids, warranting careful evaluation of rapidly enlarging or atypical lesions. See also epidermoid cyst, teratoma, neoplasm.