Dermoids (synonym dermoid cysts) are benign cystic formations that develop as a result of immersion in the embryonic period of particles of the ectodermal germ layer in the underlying tissues or as a result of the malformation of all three germ layers. In the latter case, these structures are called teratomas (see). Dermoids can be in different parts of the body - on the face, in the neck, in the neck, in the mediastinum , the sacral area, and also in the ovaries. A dermoid is a single-chamber, less commonly a multi-chamber cyst containing a greasy substance, horny masses, and hair . Most often found in the skin (epidermoids) in the form of a spherical soft tumor resembling atheroma, often with skin thinning over it. Sometimes inflamed and suppurate. In the mediastinum detected by x-ray in the form of a spherical rounded shadow. The ovaries are defined as a cyst or tumor. Surgical treatment - removal.