Teratoma is an embryonic cell tumor developing from endo-exo- and mesoderm layers. It can be benign or malignant. It is located in the testicles, ovaries or extragonadally. Small benign tumors are asymptomatic. Large teratomas cause compression of nearby organs with the appearance of appropriate symptoms. Malignant neoplasms can metastasize. The diagnosis is made on the basis of complaints, examination, radiography, ultrasound, CT, MRI, biopsy and other studies. Treatment – surgery, radiotherapy, chemotherapy.
Meaning
Teratoma is a germinogenic tumor containing areas of tissue or organs atypical for the location of the neoplasm. It can include hair, bone, muscle, cartilage, adipose, glandular and nervous tissue, less often – parts of the human body (limb, trunk, eye). It is usually diagnosed in childhood and adolescence. Sometimes it is detected in utero. Large teratomas that have arisen in the prenatal period can hinder the development of the fetus and complicate the course of labor.
Teratomas account for 24-36% of the total number of tumors in children and 2.7-7% in adults. Gradually increase in size as the body grows. They often manifest during periods of hormonal adjustment. In most cases, teratomas are considered a prognostically favorable disease. Treatment is carried out by specialists in the field of oncology, gynecology, urology, andrology, neurology, otolaryngology, pulmonology and other specialties (depending on the localization of the neoplasm).
Causes
The etiofactors of teratoma development are not precisely established. It is assumed that the tumor arises as a result of violations of embryogenesis. Teratomas originate from primary germ cells, which in the process of development must transform into eggs or into spermatozoa. Sometimes this process is disrupted, undifferentiated gonocytes remain in the body, which, under the influence of certain factors, begin to transform and give rise to various tissues of the human body.
Teratomas are often detected in the tissues of the testicles or ovaries, but they can also occur extragonadally. The reason for the atypical localization of teratomas is the delay in the advancement of the embryonic epithelium to the sites of the gonads. 25-30% of tumors are located in the ovarian region, 25-30% – in the sacrum and coccyx, 10-15% – in the retroperitoneal space, 5-7% – in the testicles, 5-7% in the presacral region, 5% – in the mediastinal zone. In addition, teratomas can be localized in the brain (more often in the ventricles of the brain or in the area of the pineal body), jaws, nasal cavity or lungs.
There is also a theory according to which part of the teratomas arises as a result of the phenomenon of “embryo in embryo” – a situation when one of two monozygotic twins in the early stages of development “wraps” around the other, and the inner twin turns into a kind of inclusion-a parasite, grossly underdeveloped and incapable of independent existence. The proof of this theory is histological studies of the tissues of some non-viable embryos.
Classification
Taking into account the features of the histological structure , there are:
- Mature teratomas are neoplasms, the study of which reveals several differentiated tissues that are derivatives of one or more germ leaves.
- Immature teratomas are tumors, the study of which reveals tissues of embryonic structure, which are derivatives of three germ leaves.
- Malignant teratomas are immature or (less often) mature teratomas combined with chorioncarcinoma, seminoma or embryonic cancer.
Mature teratomas of cystic and solid structure are isolated. A solid tumor is a dense, smooth or lumpy node. The tissue of the node on the incision is heterogeneous, light gray, with small cysts and dense inclusions (foci of bone and cartilage tissue). A mature cystic teratoma looks like a large smooth node. The incision shows large cysts containing mucus, cloudy liquid or a mushy mass. Bone and cartilage inclusions, teeth or hair may be found in the cavities.
Microscopic examination of mature solid and cystic teratomas reveals a similar pattern. The basis of neoplasms is represented by fibrous tissue, in which random inclusions of other tissues are visible: multilayer squamous epithelium, epithelium of mucous membranes, bone, cartilage, adipose and smooth muscle tissue, peripheral nerve tissue and brain tissue. Sometimes fragments of lung and kidney tissue are found in the teratoma, as well as areas of a glandular structure resembling the tissue of the breast, pancreas and salivary glands. Cystic mature teratomas are dermoid cysts, the walls of which are covered with epithelium containing hair follicles, sebaceous and sweat glands.
Immature teratomas on the incision are light gray, with small cysts, contain inclusions of immature integumentary epithelium, neurogenic epithelium, striated muscles and cartilage tissue. Mature teratomas are considered benign tumors, immature ones are considered as potentially malignant. Malignancy is rarely observed. With malignancy, neoplasms give lymphogenic and hematogenic metastases. In their structure, metastatic tumors resemble an immature teratoma or one of its components.
Types
Testicular teratomas account for approximately 40% of the total number of germinogenic neoplasms in men. Small tumors can be asymptomatic, large nodes are easily detected because they cause external deformation of the testicle. They usually begin to grow at puberty. In adult men, they are extremely rare. They can be mature, immature and malignant. Rare immature malignated teratomas in the area of an undescended testicle are of particular danger – such neoplasms are asymptomatic for a long time, are not detected during a routine examination and are diagnosed at late stages.
Ovarian teratoma are diagnosed more often than testicular tumors. They make up 20% of the total number of ovarian neoplasms. In most cases, they are mature nodes of cystic structure. Sometimes there are immature teratomas. They often proceed asymptomatically, become an accidental finding during research in connection with suspicion of other diseases. They can become active during periods of hormonal adjustment (in adolescence, during gestation, less often during menopause).
Sacrococcygeal teratoma is the most common congenital tumor. Sacrococcygeal teratoma is a rounded tumor-like formation with a diameter of 1-2 to 30 cm. Girls suffer more often than boys. Large teratomas provoke displacement of internal organs and can cause fetal development disorders. There may be anomalies in the development of the pelvis, displacement of the rectum, urethral atresia or hydronephrosis. Large tumors with intensive blood supply can provoke the development of heart failure. Taking into account the peculiarities of the location, there are 4 types of teratomas: mainly external, external-internal, internal and presacral. Large teratomas can complicate the course of labor. Neoplasms are surgically removed in the first six months of a child’s life.
Neck teratoma is a rare neoplasm. It is usually diagnosed immediately after birth. Small tumors sometimes remain unrecognized and are detected after the activation of growth. The size of the teratoma can range from 3 to 10-15 cm. Depending on the condition of the nearby anatomical formations (presence or absence of compression), they are asymptomatic or manifest as difficulty breathing, cyanosis of the skin, suffocation and difficulty eating.
Mediastinal teratoma are usually located in the anterior mediastinum, next to large vessels and the pericardium. They don’t show up for a long time. They usually begin to grow in adolescence or during gestation. They can increase up to 20-25 cm . They squeeze the lungs, heart, pleura and blood vessels. Compression of internal organs is accompanied by increased heart rate, heart pain, shortness of breath and cough. When a mediastinal teratoma breaks through into the bronchus or pleural cavity, cyanosis of the skin, suffocation, fever, asymmetry of the chest, hiccups, radiating pain in the area of the upper arm on the side of the lesion occurs. Possible pulmonary bleeding and the development of aspiration pneumonia.
Teratoma of the brain is rarely detected. It is usually diagnosed in boys 10-12 years old. It is prone to malignancy, malignant degeneration is observed in more than half of cases. It is asymptomatic for a long time. When magnified, it causes headache, nausea and dizziness.
Diagnostics
To identify sacrococcygeal teratomas, an adequate examination of the fetus during intrauterine development plays a leading role. The diagnosis is usually made based on the results of obstetric ultrasound. In other cases, the diagnosis is carried out on the basis of complaints, objective examination data, laboratory and instrumental studies. With mediastinal teratomas and sacrococcygeal neoplasms, an overview radiography is prescribed, if necessary, X-ray contrast studies and angiography are performed.
A highly informative way to diagnose teratomas is CT of the affected area. The technique allows to determine the shape, size and structure of the tumor, as well as to assess its relationship with other anatomical structures. If metastases are suspected, CT, MRI, chest X-ray, scintigraphy and other studies are prescribed. As a clarifying method, a blood test for chorionic gonadotropin and alpha-fetoprotein is used. The final diagnosis is made taking into account the results of a puncture biopsy and subsequent microscopic examination of the material.
Treatment
The treatment is surgical. Benign tumors are usually excised within healthy tissues. The exception is ovarian teratomas. Girls and women of reproductive age with this disease undergo partial resection of the ovaries, in the preclimacteric and menopausal period, adnexectomy, supravaginal amputation of the uterus with appendages is performed. The volume of surgical intervention in malignant teratomas is determined by the localization and prevalence of the neoplasm. In the postoperative period, radiotherapy and chemotherapy are prescribed.
Forecast
The prognosis depends on the localization and features of the histological structure of the teratoma. In mature and immature benign tumors, the outcome is usually favorable with the exception of large sacrococcygeal teratomas. The survival rate for neoplasms of this localization is about 50%. The cause of death is malformations, compression of internal organs or rupture of a teratoma in childbirth. In malignant tumors, the prognosis is determined by the prevalence of the process. Teratomas with seminoma proceed more favorably compared with teratomas in combination with chorionepithelioma or embryonic cancer.