The term, “Dermoid cyst” was coined by Leblanc in 1831 within the veterinary literature when he removed a lesion that resembled skin at the bottom of a horse's skull, which he called a “kyste dermoid”. Both “dermoid” and “teratoma” are now quite a century old, are in general use and sometimes used interchangeably. Earliest implications were that dermoids composed of elements like skin and its appendages, while teratomas had no such limits. Dermoids now are often being recognized as trigerminal and practically containing any kind of tissue.
Strictly speaking, dermoids are tumors that maintain orderly arrangements. They have well-differentiated ectodermal and mesodermal tissues surrounding endodermal components. Teratomas, specifically solid teratomas do not show any such organization. Thus, the presence of a point of organization, a high degree of cellular differentiation, and cystic structure differentiates dermoids from teratomas. The workup for cystic teratomas is essentially radiographic, and their appearance is analogous despite varying locations.
Mature cystic teratomas of the ovaries can be removed by simple cystectomy instead of salpingo-oophorectomy. Removal of the dermoid cyst is generally the treatment of choice. This can be done by laparotomy (open surgery) or laparoscopy (with a scope). Torsion of the ovary by the cyst is an emergency and requires urgent surgery.
Complications of ovarian teratomas include torsion, rupture, infection, hemolytic anemia, autoamputation and malignant degeneration. Torsion is by far the most significant cause of morbidity, occurring in 3-11% of all cases. Several series have demonstrated that increasing tumor size correlates with increased risk of torsion[2,5].
Rupture of a cystic teratoma is although rare but may be spontaneous or associated with torsion. Most case series report a rate of less than 1%[1,2] though Ahan et al reported a rate of 2.5% in their report of 501 patients. Rupture may be a sudden occurrence, leading to shock or hemorrhage with acute chemical peritonitis. Chronic leakage can also occur leading to granulomatous peritonitis. Prognosis after rupture is usually favorable, but the rupture often results in formation of dense adhesions. Infection is uncommon and occurs in less than 1-2% of cases. Coliform bacteria are the organisms most commonly implicated [5,6].
Autoimmune hemolytic anemia is also an association with mature cystic teratomas in rare cases. In these cases, removal of the tumor resulted in complete disappearance of symptoms. Pathogenic mechanisms may be: (1) Antigenically different tumor substances from the host produce an antibody response which cross react with native RBCs, (2) Coating of the RBCs by tumor substance can change the RBC antigenicity. Hence, radiologic imaging of the pelvis is done in cases of refractory hemolytic anaemia[6,7].
Mature cystic teratoma of the ovary is almost always benign, but may undergo malignant transformation in 0.2 to 2% cases into one of its elements. The majority of the malignant ones are squamous cell carcinomas. Elevated serum alpha-fetoprotein and beta-human chorionic gonadotropin levels are suggestive of malignancy. The prognosis is poor for patients with malignant degeneration but generally depends on the stage and degenerated cell type [9,10].