Yolk sac carcinomas
Yolk sac carcinomas, also referred to as endodermal sinus tumors, are a type of tumor that arises from primitive germ tissue, resembling the yolk sac. These tumors are most commonly associated with testicular cancer in children, constituting about 80% of testicular tumors in boys. While they primarily affect the testes, yolk sac carcinomas can also occur in the ovaries. Generally categorized as nonseminomas, these tumors do not produce sperm cells.
One notable risk factor for developing testicular carcinomas is cryptorchidism, a condition where one or both testicles fail to descend, which increases the risk by three to four times. Diagnosing yolk sac carcinomas typically involves a biopsy and blood tests to measure elevated levels of alpha-fetoprotein (AFP), a biomarker associated with these tumors. The standard treatment approach includes surgical removal of the affected testicle, often accompanied by chemotherapy, which can include drugs such as vincristine and cyclophosphamide. When detected early, particularly in children, the prognosis is generally good, with survival rates around 90% when treated effectively. Understanding yolk sac carcinomas is essential for recognizing their implications and treatment options for those affected.
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Yolk sac carcinomas
ALSO KNOWN AS: Endocervical sinus tumors, endodermal sinus tumors, orchidoblastomas
RELATED CONDITIONS: Testicular carcinomas
DEFINITION: Yolk sac carcinomas are tumors that originate in the primitive germ tissue of humans, the cells of which resemble the yolk sac. The most common form of yolk sac carcinoma is testicular cancer in children, though the ovaries may also develop this form of disease. Yolk sac carcinomas are generally in a class known as nonseminomas, referring to the absence of sperm-producing cells.
Risk factors: Most men who develop testicular carcinomas have no known risk factors. However, cryptorchidism, a lack of descent of one or both testicles, is associated with an increased risk. According to a study published in 2017, men with cryptorchidism are three to four times more likely to develop testicular cancer. Lack of descent is not rare, with the testicles remaining in the groin region in some 3 to 5 percent of male children. Most cases of testicular cancer that do occur develop in the undescended testicle. The molecular basis for the association is unknown, but scientists believe the two conditions are the result of a similar genetic factor rather than the direct result of the lack of descent. The condition can be corrected through surgery.
Etiology and the disease process: Most cancers that originate within the testicles are germ-cell tumors (GSTs), malignancies that develop in cells associated with sperm production. Most are seminomas, malignancies of sperm-producing cells, with the remainder nonseminomas, malignancies of other embryonal cell types.
Incidence: According to the American Urological Association, malignant yolk sac tumors are the most common type of testicular cancer in children. They make up 80 percent of testicular tumors in boys. The incidence of pure malignant yolk sac carcinoma in adult males is rare. The actual chance of a man developing testicular cancer is low, with approximately 1 in 250 men at risk in a lifetime, according to the American Cancer Society.
Symptoms: Nonseminomas such as yolk sac carcinomas release alpha-fetoprotein (AFP), which can be measured in blood samples. Alpha-fetoprotein is synthesized by the yolk sac during fetal development, and elevated levels may suggest a malignancy.
Screening and diagnosis: Diagnosis is based on a biopsy of tissues, carried out in conjunction with the finding of elevated levels of alpha-fetoprotein.
Treatment and therapy: Surgical removal of the testicle is the treatment of choice. Chemotherapy may also be warranted depending on the extent of the disease and may include combinations of vincristine, actinomycin D, and cyclophosphamide.
Prognosis, prevention, and outcomes: Testicular carcinomas in children, when diagnosed early in their development, can usually be treated successfully. Similar malignancies developing in adults are more problematic, and prognosis depends on the stage of development and the types of cells associated with the tumor. With a combination of chemotherapy and surgery, 90 percent of patients with yolk sac carcinomas survive.
Bibliography
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