| Germ-cell tumor | |
|---|---|
 | |
| Micrograph of a seminoma, a common germ cell tumor. | |
| Specialty | Oncology |
Germ cell tumor (GCT) is a neoplasm derived from the primordial germ cells. [1] Germ-cell tumors can be cancerous or benign. Germ cells normally occur inside the gonads (ovary [2] and testis). GCTs that originate outside the gonads may be birth defects resulting from errors during development of the embryo.
GCTs are classified by their histology, [4] regardless of location in the body. However, as more information about the genetics of these tumors become available, they may be classified based on specific gene mutations that characterize specific tumors. [5] They are broadly divided in two classes: [6]
The two classes reflect an important clinical difference. Compared with germinomatous tumors, nongerminomatous tumors tend to grow faster, have an earlier mean age at time of diagnosis (around 25 years versus 35 years, in the case of testicular cancers), and have a lower five-year survival rate. The survival rate for germinomatous tumors is higher in part because these tumors are very sensitive to radiation, and they also respond well to chemotherapy. The prognosis for nongerminomatous tumours has improved dramatically, however, due to the use of platinum-based chemotherapy regimens. [7]
| Tumor | ICD-O | Peak Age (yr) | Benign or malignant | Histology | Tumor marker |
|---|---|---|---|---|---|
| Germinoma (including dysgerminoma and seminoma) | 40–50 | Malignant | Sheets of uniform polygonal cells with cleared cytoplasm; lymphocytes in the stroma | About 10% have elevated hCG | |
| Dysgerminoma | M9060/3 | ||||
| Seminoma | M9061/3 | Placental alkaline phosphate (PLAP) [8] |
| Tumor | ICD-O | Peak Age (yr) | Benign or malignant | Histology | Tumor marker |
|---|---|---|---|---|---|
| Embryonal carcinoma | 9070/3 | 20–30 | Malignant | Poorly differentiated, pleomorphic cells in cords, sheets, or papillary formation | secrete hCG, AFP |
| Endodermal sinus tumor, also known as yolk sac tumor (EST, YST) | 9071/3 | 3 | Malignant | Poorly differentiated endothelium-like, cuboidal, or columnar cells | 100% secrete AFP |
| Choriocarcinoma | 9100/3 | 20–30 | Malignant | Cytotrophoblast and syncytiotrophoblast without villus formation | 100% secrete hCG |
| Teratoma including mature teratoma, dermoid cyst, immature teratoma, teratoma with malignant transformation | 9080/0-9080/3 | 0–3, 15–30 | Mature teratoma, dermoid cyst usually benign (but follow-up required); others usually malignant | Very variable, but "normal" tissues are common | Pure tumors do not secrete hCG, AFP |
| Polyembryoma | 9072/3 | 15–25 | ? | ? | ? |
| Gonadoblastoma | 9073/1 | ? | ? | ? | ? |
| Tumor | ICD-O | Peak Age (yr) | Benign or malignant | Histology | Tumor marker |
|---|---|---|---|---|---|
| Mixed | 15–30 | Malignant | Depends on elements present | Depends on elements present |
Mixed germ cell tumors occur in many forms. Among these, a common form is teratoma with endodermal sinus tumor.
Teratocarcinoma refers to a germ cell tumor that is a mixture of teratoma with embryonal carcinoma, or with choriocarcinoma, or with both. [9] This kind of mixed germ cell tumor may be known simply as a teratoma with elements of embryonal carcinoma or choriocarcinoma, or simply by ignoring the teratoma component and referring only to its malignant component: embryonal carcinoma and/or choriocarcinoma. They can present in the anterior mediastinum.[ citation needed ]
Some investigators suggest that this distribution arises as a consequence of abnormal migration of germ cells during embryogenesis. Others hypothesize a widespread distribution of germ cells to multiple sites during normal embryogenesis, with these cells conveying genetic information or providing regulatory functions at somatic sites.[ citation needed ]
Extragonadal GCTs were thought initially to be isolated metastases from an undetected primary tumor in a gonad, but many germ cell tumors are now known to be congenital and originate outside the gonads. The most notable of these is sacrococcygeal teratoma, the single most common tumor diagnosed in babies at birth.[ citation needed ]
Of all anterior mediastinal tumors, 15–20% are GCTs of which about 50% are benign teratomas. [10] Ovarian teratomas may be associated with anti-NMDA receptor encephalitis. [11]
Despite their name, GCTs occur both within and outside the ovary and testis. They are found in:[ citation needed ]}
In females, GCTs account for 30% of ovarian tumors, but only 1 to 3% of ovarian cancers in North America. In younger women, they are more common, thus in patients under the age of 21, 60% of ovarian tumors are of the germ-cell type, and up to one-third are malignant. In males, GCTs of the testis occur typically after puberty and are malignant (testicular cancer). In neonates, infants, and children younger than 4 years, most are sacrococcygeal teratomas.[ citation needed ]
Males with Klinefelter syndrome have a 50 times greater risk of GSTs. [12] In these persons, GSTs usually contain nonseminomatous elements, present at an earlier age, and seldom are gonadal in location.[ medical citation needed ]
Women with benign GCTs such as mature teratomas (dermoid cysts) are cured by ovarian cystectomy or oophorectomy. [13] In general, all patients with malignant GCTs have the same staging surgery that is done for epithelial ovarian cancer. [14] If the patient is in her reproductive years, an alternative is unilateral salpingoophorectomy, while the uterus, the ovary, and the fallopian tube on the opposite side can be left behind. This is not an option when the cancer is in both ovaries. If the patient has finished having children, the surgery involves complete staging, including salpingoophorectomy on both sides, as well as hysterectomy. [13]
Patients with germ-cell cancer often need to be treated with combination chemotherapy for at least three cycles, but female patients with early-stage disease may not require this treatment. [15] The chemotherapy regimen most commonly used in GCTs is called PEB (or BEP), and consists of bleomycin, etoposide, and a platinum-based antineoplastic (cisplatin). [13] Targeted treatments, such as immunotherapy, hormonal therapy and kinase inhibitors, are being evaluated for tumors that do not respond to chemotherapy. [16]
The 1997 International Germ Cell Consensus Classification [17] is a tool for estimating the risk of relapse after treatment of malignant germ-cell tumor.
A small study of ovarian tumors in girls [18] reports a correlation between cystic and benign tumors, and conversely, solid and malignant tumors. Because the cystic extent of a tumor can be estimated by ultrasound, MRI, or CT scan before surgery, this permits selection of the most appropriate surgical plan to minimize risk of spillage of a malignant tumor.[ citation needed ]
Access to appropriate treatment has a large effect on outcome. A 1993 study of outcomes in Scotland found that for 454 men with nonseminomatous (nongerminomatous) GCTs diagnosed between 1975 and 1989, five-year survival increased over time and with earlier diagnosis. Adjusting for these and other factors, survival was 60% higher for men treated in a cancer unit that treated the majority of these men, though the unit treated more men with the worst prognosis. [19]
Choriocarcinoma of the testicles has the worst prognosis of all germ-cell cancers. [20]
A teratoma is a tumor made up of several different types of tissue, such as hair, muscle, teeth, or bone. Teratomata typically form in the tailbone, ovary, or testicle.
Testicular cancer is cancer that develops in the testicles, a part of the male reproductive system. Symptoms may include a lump in the testicle or swelling or pain in the scrotum. Treatment may result in infertility.
A bone tumor is an abnormal growth of tissue in bone, traditionally classified as noncancerous (benign) or cancerous (malignant). Cancerous bone tumors usually originate from a cancer in another part of the body such as from lung, breast, thyroid, kidney and prostate. There may be a lump, pain, or neurological signs from pressure. A bone tumor might present with a pathologic fracture. Other symptoms may include fatigue, fever, weight loss, anemia and nausea. Sometimes there are no symptoms and the tumour is found when investigating another problem.
Ovarian cancer is a cancerous tumor of an ovary. It may originate from the ovary itself or more commonly from communicating nearby structures such as fallopian tubes or the inner lining of the abdomen. The ovary is made up of three different cell types including epithelial cells, germ cells, and stromal cells. When these cells become abnormal, they have the ability to divide and form tumors. These cells can also invade or spread to other parts of the body. When this process begins, there may be no or only vague symptoms. Symptoms become more noticeable as the cancer progresses. These symptoms may include bloating, vaginal bleeding, pelvic pain, abdominal swelling, constipation, and loss of appetite, among others. Common areas to which the cancer may spread include the lining of the abdomen, lymph nodes, lungs, and liver.
Choriocarcinoma is a malignant, trophoblastic cancer, usually of the placenta. It is characterized by early hematogenous spread to the lungs. It belongs to the malignant end of the spectrum in gestational trophoblastic disease (GTD). It is also classified as a germ cell tumor and may arise in the testis or ovary.
Surface epithelial-stromal tumors are a class of ovarian neoplasms that may be benign or malignant. Neoplasms in this group are thought to be derived from the ovarian surface epithelium or from ectopic endometrial or Fallopian tube (tubal) tissue. Tumors of this type are also called ovarian adenocarcinoma. This group of tumors accounts for 90% to 95% of all cases of ovarian cancer; however is mainly only found in postmenopausal women with the exception of the United States where 7% of cases occur in women under the age of 40. Serum CA-125 is often elevated but is only 50% accurate so it is not a useful tumor marker to assess the progress of treatment. 75% of women with epithelial ovarian cancer are found within the advanced-stages; however younger patients are more likely to have better prognoses than older patients.
Sertoli–Leydig cell tumour is a group of tumors composed of variable proportions of Sertoli cells, Leydig cells, and in the case of intermediate and poorly differentiated neoplasms, primitive gonadal stroma and sometimes heterologous elements.
Granulosa cell tumours are tumours that arise from granulosa cells. They are estrogen secreting tumours and present as large, complex, ovarian masses. These tumours are part of the sex cord–gonadal stromal tumour or non-epithelial group of tumours. Although granulosa cells normally occur only in the ovary, granulosa cell tumours occur in both ovaries and testicles. These tumours should be considered malignant and treated in the same way as other malignant tumours of ovary. The ovarian disease has two forms, juvenile and adult, both characterized by indolent growth, and therefore has high recovery rates. The staging system for these tumours is the same as for epithelial tumours and most present as stage I. The peak age at which they occur is 50–55 years, but they may occur at any age.
Sex cord–gonadal stromal tumour is a group of tumors derived from the stromal component of the ovary and testis, which comprises the granulosa, thecal cells and fibrocytes. In contrast, the epithelial cells originate from the outer epithelial lining surrounding the gonad while the germ cell tumors arise from the precursor cells of the gametes, hence the name germ cell. In humans, this group accounts for 8% of ovarian cancers and under 5% of testicular cancers. Their diagnosis is histological: only a biopsy of the tumour can make an exact diagnosis. They are often suspected of being malignant prior to operation, being solid ovarian tumours that tend to occur most commonly in post menopausal women.
A dysgerminoma is a type of germ cell tumor; it usually is malignant and usually occurs in the ovary.
A seminoma is a germ cell tumor of the testicle or, more rarely, the mediastinum or other extra-gonadal locations. It is a malignant neoplasm and is one of the most treatable and curable cancers, with a survival rate above 95% if discovered in early stages.
A germinoma is a type of germ-cell tumor, which is not differentiated upon examination. It may be benign or malignant.
Mediastinal germ cell tumors are tumors that derive from germ cell rest remnants in the mediastinum. Germ cell tumors most commonly occur in the gonad but occasionally elsewhere.
Ovarian tumors, or ovarian neoplasms, are tumors arising from the ovary. They can be benign or malignant. They consist of mainly solid tissue, while ovarian cysts contain fluid.
An immature teratoma is a teratoma that contains anaplastic immature elements, and is often synonymous with malignant teratoma. A teratoma is a tumor of germ cell origin, containing tissues from more than one germ cell line, It can be ovarian or testicular in its origin. and are almost always benign. An immature teratoma is thus a very rare tumor, representing 1% of all teratomas, 1% of all ovarian cancers, and 35.6% of malignant ovarian germ cell tumors. It displays a specific age of incidence, occurring most frequently in the first two decades of life and almost never after menopause. Unlike a mature cystic teratoma, an immature teratoma contains immature or embryonic structures. It can coexist with mature cystic teratomas and can constitute of a combination of both adult and embryonic tissue. The most common symptoms noted are abdominal distension and masses. Prognosis and treatment options vary and largely depend on grade, stage and karyotype of the tumor itself.
Leydig cell tumour, also Leydig cell tumor, (testicular) interstitial cell tumour and (testicular) interstitial cell tumor, is a member of the sex cord-stromal tumour group of ovarian and testicular cancers. It arises from Leydig cells. While the tumour can occur at any age, it occurs most often in young adults.
Endodermal sinus tumor (EST) is a member of the germ cell tumor group of cancers. It is the most common testicular tumor in children under three, and is also known as infantile embryonal carcinoma. This age group has a very good prognosis. In contrast to the pure form typical of infants, adult endodermal sinus tumors are often found in combination with other kinds of germ cell tumor, particularly teratoma and embryonal carcinoma. While pure teratoma is usually benign, endodermal sinus tumor is malignant.
Scrotalultrasound is a medical ultrasound examination of the scrotum. It is used in the evaluation of testicular pain, and can help identify solid masses.
An extracranial germ cell tumor (EGCT) occurs in the abnormal growth of germ cells in the gonads and the areas other than the brain via tissue, lymphatic system, or circulatory system. The tumor can be benign or malignant (cancerous) by its growth rate. According to the National Cancer Institute and St. Jude Children's Research Hospital, the chance of children who are under 15 years old having EGCTs is 3%, in comparison to adolescents, a possibility of 14% with aged 15 to 19 can have EGCTs. There is no obvious cut point in between children and adolescents. However, common cut points in researches are 11 years old and 15 years old.
Ovarian germ cell tumors (OGCTs) are heterogeneous tumors that are derived from the primitive germ cells of the embryonic gonad, which accounts for about 2.6% of all ovarian malignancies. There are four main types of OGCTs, namely dysgerminomas, yolk sac tumor, teratoma, and choriocarcinoma.
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