In theory, teratomas are usually germ cell tumors that affect the germ layers. They occur as benign and malignant tumor growths in which some teratomas are highly specialized. This implies that, highly specialized teratomas are located with one germ layer; thus referred to as monodermal teratomas, whereas others occur with two or three germ layers. As such, these teratomas are classified as trigerminal because they can affect any of the three germ layers. For instance, dermoids are a group of teratomas that are recognized as trigerminal because they can occur in any of the germ layers of many tissues.
It is worth noting that teratomas begin as benign swellings and undergo transformation to become malignant. In practice, dermoids have been found to exhibit an orderly arrangement in which endodermal components are surrounded by well-differentiated mesodermal and ectodermal tissues. However, solid teratomas do not exhibit a high degree of cellular organization and differentiation.
Therefore, this paper will provide an overview of teratomas. It will discuss their causes, pathophysiology, clinical diagnosis and treatment, in order to create an overall understanding on these tumors.
Inhaltsverzeichnis
Introduction
Causes of Teratomas
Pathophysiology of Teratomas
Classification of Teratomas
Sacrococcygeal Teratomas
Ovarian Teratomas
Testicular Teratomas
Mediastinal Teratomas
Diagnosis for Teratomas
Treatment for Teratomas
Conclusion
References
Introduction
In theory, teratomas are usually germ cell tumors that affect the germ layers. They occur as benign and malignant tumor growths in which some teratomas are highly specialized. This implies that, highly specialized teratomas are located with one germ layer; thus referred to as monodermal teratomas, whereas others occur with two or three germ layers (Acton, 2012). As such, these teratomas are classified as trigerminal because they can affect any of the three germ layers. For instance, dermoids are a group of teratomas that are recognized as trigerminal because they can occur in any of the germ layers of many tissues. It is worth noting that, teratomas begin as benign swellings and undergo transformation to become malignant. In practice, dermoids have been found to exhibit an orderly arrangement in which endodermal components are surrounded by well-differentiated mesodermal and ectodermal tissues. However, solid teratomas do not exhibit a high degree of cellular organization and differentiation (Acton, 2012). Therefore, this paper will provide an overview of teratomas. It will discuss their causes, pathophysiology, clinical diagnosis and treatment, in order to create an overall understanding on these tumors.
Causes of Teratomas
Over the centuries, the causes of teratomas have been surrounded by an unprecedented debate and speculation. However, epidemiological studies have identified the cause of teratomas to be associated with meiotic embryonic cell divisions. According to the parthenogenic theory, teratomas are believed to originate from the primordial germ cells. The theory is supported by the characteristic anatomic distribution of teratomas. It has been observed that, teratomas are distributed along lines of migration in which primordial germ cells migrate from the embryonic yolk sac to other tissues such as the primitive gonads. This phenomenon has been confirmed through the investigation of cystic teratomas that occur within the ovaries in which cytogenetic techniques demonstrate the development of teratomas the germ cells from embryonic single germ cells.
It is also believed that teratomas are associated with other cancers. A close correlation between some teratomas and acute myelogenous leukemia, malignant histiocytosis, myelodysplasia and embryonal rhabdomyosarcoma has been identified (McColl, 2011).
Pathophysiology of Teratomas
From an anatomical perspective, the biology of teratomas can be explained by their pathophysiology. Teratomas comprise of parenchymal cell types of the three germ layers. In most cases, teratoma tumors are either paraxial or midline, and this aspect is attributable to their origin, totipotential cells (Kumar et al., 2005). This explains why most teratoma tumors are located in the sacrococcygeal region. Epidemiological investigations show that sacrococcygeal teratoma tumors account for about 57 percent of all teratomas. On the other hand, most teratomas have been found to exhibit gonadal location, primarily in the ovaries. However, some tumors occur in the testes at a low frequency compared to ovarian teratomas. In general, teratomas with gonadal locations have been found to account for 29 percent of all teratomas. In most cases, cystic teratomas have been observed to occur in midline embryonic cells. There are also mediastinal that accounts for 7 percent and retroperitoneal. Retroperitoneal tumors account for 4 percent whereas cervical teratomas account for 3 percent. Moreover, teratomas have also been found to have intracranial location and this account for 3 percent (Acton, 2012). Ordinarily, teratomas recapitulate most body tissues including the skin, teeth, muscle and the fat tissue. They also affect the hair, as well as, the endocrine tissues.
In general, teratomas are manifested by a number of symptoms. Some of the most common symptoms of teratomas include shortness of breath, fatigue, cough and chest pain or pressure. They are also manifested by the formation of lumps, inflammation, swellings and tenderness of the affected tissue.
Classification of Teratomas
Teratomas are classified into four principal forms depending on their location in the body. These forms are sacrococcygeal, ovarian, testicular and mediastinal teratomas.
Sacrococcygeal Teratomas
Sacrococcygeal teratomas are the most prevalent of all teratomas, and they are diagnosed during the prenatal period. In this form of teratoma, tumor hemorrhage and polydramnios are usually the most common signs characterized by non-immune hydrops fetalis and anemia. It is believed that hydrops serve as the most significant ominous sign in which the development of hydrops during the first and second trimesters corresponds to a mortality rate of 93 percent. On the other hand, the development of hydrops during the third trimester causes few complications; thus, its mortality rate is 25 percent (Acton, 2012).
Ovarian Teratomas
Ovarian teratomas are characterized by anemia and they encompass some complications including torsion, malignant degeneration, infection and rupture of cystic teratomas. Evidence shows that torsion accounts for the highest rate of morbidity ranging from 3-11% of all teratoma complications (Acton, 2012). However, it is worth noting that, mature ovarian teratomas exhibit benign characteristic. This implies that, there are no complications associated with mature cystic teratomas.
Testicular Teratomas
Testicular teratomas exist as benign tumors, and they occur predominantly among infants and children, although 3% of these teratomas occur in adults. However, testicular teratomas have been found to metastasize in adults whereby they affect the retroperitoneal lymph nodes and other systems.
Mediastinal Teratomas
Mediastinal teratomas are more or less the same as testicular teratomas because they are benign tumors, although their anatomical locations differ significantly. Mediastinal teratomas are mediastinal germ cell tumors that affect the mediastinum, although they affect other intrathoracic structures, especially during complications (Shukla et al., 2004).
Diagnosis for Teratomas
Ordinarily, diagnosis of teratomas involves an array of diagnostic approaches including physical examination, scanning and blood test. Physical examination focuses on identifying any blockage of veins in the chest area. On the other hand, a chest X-ray help in diagnosing the tumor, whereas CT scans of the abdomen and the pelvis help in diagnosing the presence of tumors in these areas. Despite the significance of these diagnostic approaches, blood tests have been the mainstay of teratoma diagnosis (Ulbright, 2005). Blood tests are performed to determine the levels of some proteins that are associated to teratomas. Some of the blood components tested are the alpha-fetoprotein (AFP) and beta-hCG. In practice, benign teratomas are differentiated from malignant tumors through the use of the core biopsy or fine-needle aspiration (Varghese & Lau, 2007).
Treatment for Teratomas
Treatment for teratomas involves chemotherapy and surgery. Ideally, chemotherapy aims at treating the tumor through the use of cytotoxic agents. In most cases, cytotoxic agents are used to prevent the spread of the tumor to other tissues or shrink the tumor. Some of the commonly used cytotoxic drugs are etoposide, cisplatin and bleomycin. The second treatment option is surgery which is recommended for mature teratomas. Ordinarily, mature cystic teratomas are removed through a simple cystectomy, whereas sacrococcygeal tumors are removed through complete excision. On the other hand, testicular teratomas are treated by radical orchiectomy. In most cases, testis-sparing techniques are used owing to their reliability (Shukla et al. 2004).
Conclusion
In a brief conclusion, teratomas are tumors that affect the germ cell layers of different tissues. These tumors have been found to have a germinal origin in which they exhibit midline migration to body tissues such as the gonads. In practice, inflammation, swellings and pain in the affected areas are considered to be the most principal signs and symptoms, although different forms of teratomas exhibit anatomical differences.
References
Acton, Q. A. (2012). Teratomas: New Insights for the Healthcare Professional: 2012 Edition: Scholarly Paper.Atlanta, GA: Scholarly Editions.
Kumar, V. et al. (2005). Pathologic Basis of Disease (7th Ed). Saunders, PA: Elsevier.
McColl, F. D. (2011). Diseases of the Diaphragm, Chest Wall, Pleura, and Mediastinum. In: Goldman L, Schafer AI, Eds. Cecil Medicine (24th Ed).Saunders, PA: Elsevier.
Shukla, A. R. et al. (2004). Experience With Testis Sparing Surgery for Testicular Teratoma. The Journal of Urology, 171(1):161–163.
Ulbright, T. M. (2005). Germ Cell Tumors of the Gonads: A Selective Review Emphasizing Problems in Differential Diagnosis, Newly Appreciated, And Controversial Issues. Modern Pathology, 18: S61–S79.
Varghese, T. K & Lau, C. L. (2007). The Mediastinum. In: Townsend CM, Beauchamp RD, Evers BM, Mattox KL, eds. Sabiston Textbook of Surgery: The Biological Basis of Modern Surgical Practice. 18. Saunders, PA: Elsevier.
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- Patrick Kimuyu (Autor), 2017, Teratomas. Creating Understanding on the Germ Cell Tumors, Múnich, GRIN Verlag, https://www.grin.com/document/385081
