Dermoid cysts, also known as benign mature cystic teratomas, most commonly develop in the ovaries, while a very small percentage was reported in the head and neck area. It belongs to the group of germ cell tumors and clinical course is commonly asymptomatic. There are numerous complications, such as torsion, rupture and in 1% of cases, malignant transformation. The diagnosis is made by imaging studies, while surgery is the mainstay of therapy.
Symptoms may be divided based on the site of its appearance. For ovarian dermoid cysts, 30-60% of patients are asymptomatic at the time of diagnosis, whereas most common complaints include abdominal pain, constipation, nausea, vomiting, anorexia and a tender abdominal pass that is palpated during physical examination  . Cysts that develop at the floor of the mouth are shown to be painless and a slow-growing mass in the submental, submandibular and sublingual region is observed . Cranial tumors manifest with headaches and seizures , while rare cases of visual and auditory deficits have been described .
Imaging studies are the main tools to establish the diagnosis of dermoid cysts. Vaginal ultrasonography may serve as an initial method to determine the presence of a fluid-filled mass, while either CT or MRI are used to confirm the diagnosis based on macroscopic criteria. CT findings include large amount of fat accumulation within the mass that can be accompanied by calcification of the cyst wall, whereas fat signaling attained by the sebaceous components of the tumor is detected by MRI . Increased values of CA-125, an ovarian tumor marker, have been observed in up to 86% of ovarian neoplasms, which is why it may be useful to determine its levels during the diagnostic workup .
Once the presence of a dermoid cyst is confirmed, surgical excision is recommended. Ovarian cysts are now more frequently managed through a laparoscopic approach, since a shorter duration of hospital stay and quicker recovery rates were observed when compared to open surgery . More importantly laparoscopic surgery may aid in preserving the ability for women during childbearing age to become pregnant later on  . For tumors that exceed 10 cm in diameter, oophorectomy together with tumor excision is usually indicated . Surgery is also readily performed for tumors of the oral cavity and those located in the cranium. The anterior fontanel is usually described as the most common cranial location of the tumor, providing a safe surgical approach .
The prognosis of dermoid cysts is excellent with an early diagnosis and appropriate treatment. However, numerous complications may arise in initially asymptomatic patients. Torsion of the cyst (occurring in approximately 10-15% of cases) , rupture that can be severely debilitating and can lead to hydrocephalus, superinfection (although very rare) , and finally, malignant transformation. Despite the fact that only 1% of patient develop malignant transformation, most commonly to squamous cell carcinoma, significantly worse outcomes may be expected in this group of patients, particularly if advanced stages of the disease are reached . Finally, infertility is also a potentially severe complication . Because adverse effects may profoundly affect the patient and cause significant morbidity, it is imperative to attain an early diagnosis.
Dermoid cysts contain cells of all three germ cell layers - ectoderm, endoderm and mesoderm and is appropriately classified into the group of germ cell tumors . Due to its mostly benign nature and morphological characteristics, together with accompanying development of cysts lined with an epidermis, it is often described in literature as benign mature cystic teratoma . Presumably, defects during embryonic development are thought to play a role, while genetic abnormalities involving chromosomes 12 and 20 have been described, but the exact cause remains unknown  . A proposed classification includes congenital, acquired and congenital dermoid inclusion cysts (CDIC), which are thought to occur as a result of dermoid cell inclusion along the embryonic fusion line .
Incidence and prevalence rates for dermoid cysts currently do not exist. Estimations suggest that this neoplasm is the most common benign germ cell tumor of the ovaries, comprising 70% of all benign ovarian tumors in women under 30 years of age . It is most frequently diagnosed in women during childbearing age , whereas 50% of pediatric ovarian tumors were shown to be dermoid cysts . On the other hand, this tumor is responsible for approximately 7% of all cysts in the head and neck area , indicating that it is rarely encountered in medical practice. Intracranial involvement is even more rare, as isolated reports determined that dermoid cysts represent not more than 0.2% of all central nervous system tumors .
The pathogenesis of dermoid cysts remains to be elucidated, but it is known that this neoplasm is a germ cell tumor and that its onset begins during embryonal development. Retention of the germinal epithelium during maturation of the bones of the head and neck, including the mandible and the hyoid arches is thought to be the main pathophysiological mechanism in the case of its development at the floor of the mouth . Ovarian dermoid cysts arise from totipotent cells and comprises all three germinal layers , which is why frequent appearance of numerous tissues, including teeth, respiratory or gastrointestinal epithelium, sweat glands and hair is commonly observed .
The fact that dermoid cysts develop during embryogenesis indicates that not much can be done in terms of prevention, but significant steps in reducing the rate of complications can be achieved through identifying this tumor in its early stages. Estimated growth rates of this tumor are around 1.8 mm per year , which means that it may take up to a few decades before symptoms may appear, which provides enough time to make a diagnosis on time. Wide-scale screening of women during childbearing age would undoubtedly increase the number of diagnosed dermoid cysts, but various other conditions could be detected in their earlier stages as well.
Although the appearance of dermoid cysts (also known as benign mature cystic teratomas) was described in various tissues, it most frequently arises in the ovaries and is considered to be the most common germ cell tumor of this organ . Additional locations include the cranium , the floor of the mouth and the parotid gland   . A dermoid cyst contains all three germ cell layers - ectoderm, endoderm and mesoderm. Because of the presence of cysts that are lined by an epidermis within the tumor, the term dermoid cyst was designated . Histologically, this tumor may contain virtually any tissue, including tooth, hair, cartilage and bronchial or gastrointestinal epithelium . The exact pathophysiological mechanism remains unknown, while current theories suggest a defect in fusion of the embryonic lateral mesenchymatic mass . Ovarian dermoid cysts are most frequently diagnosed in younger women during childbearing age with almost one third of cases being asymptomatic at the time of diagnosis . Abdominal pain may be the only reported symptom, whereas a palpable abdominal mass may be observed during physical examination . Dermoid cysts confined to the cranium may cause symptoms such as headaches, seizures and can even provoke hydrocephalus in the case of rupture , while the clinical presentation of tumors in the floor of the mouth comprises the appearance of a painless, slow-growing mass in sulingual, submandibular and submental regions . Imaging techniques such as ultrasonography (both abdominal and vaginal), followed by computed tomography (CT) and magnetic resonance imaging (MRI) are considered as optimal diagnostic procedures . Regardless of the location of the tumor, surgical excision is the mainstay of therapy. A laparoscopic approach for ovarian dermoid cysts has shown very good results in terms of hospital stay and rate of recovery in comparison to classical open surgery . This tumor can cause numerous complications, such as torsion, rupture, even superinfection and in rare cases, malignant transformation , some of them potentially causing significant disability and morbidity. Approximately 1% of all dermoid cysts have shown to transform into a malignant variant, most commonly to squamous cell carcinoma . Another important complication is infertility, which is why it is necessary to consider this tumor in the differential diagnosis of pelvic symptoms when other more common conditions are excluded.
A dermoid cyst (also known in literature as benign mature cystic teratoma) is a tumor that most commonly develops in the ovaries and less commonly in the head and neck area. It stems from alterations during embryonal development and is derived from totipotent cells, which are able to differentiate into virtually any cell type. Tooth tissue, but also sweat gland, hair, cartilage and respiratory or gastrointestinal epithelium can be found during microscopic examination and it's annual growth rate is established to be around 2 millimeters per year. In addition to numerous cell types, it contains a cyst that has an epithelium, hence the name dermoid cyst. Its presence in ovaries is most frequently diagnosed among young women during childbearing age, whereas head and neck tumors are identified in children in most cases. It is not uncommon for patients to be completely asymptomatic and the diagnosis can often be made incidentally, but symptoms such as abdominal pain, nausea, vomiting and a palpable tender mass in the stomach may be reported in ovarian tumors. On the other hand, seizures, headaches and a painless mass growing below the tongue are seen in patients with head and neck tumors, respectively. To make the diagnosis, imaging studies such as ultrasonography, computed tomography (CT scan) or magnetic resonance imaging (MRI) should be performed. Treatment almost always includes excision of the tumor. Laparoscopy has been recommended in ovarian tumors as it provides a shorter duration of stay and a faster recovery rate compared to open surgery, but more importantly, it provides women with an opportunity to become pregnant after successful surgery. The overall prognosis of patients suffering from dermoid cysts are very good if they are identified in the asymptomatic stages, but numerous debilitating and potentially life-threatening complications can arise. Twisting of the tumor (known as torsion) occurs in 10-15% of cases, whereas more severe complications include rupture and infertility, which further emphasizes the importance of an early diagnosis.