Germ cell tumor
| Germ cell tumor | |
|---|---|
 |
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| Micrograph of a seminoma, a common germ cell tumor. | |
| Classification and external resources | |
| Specialty | Oncology |
| ICD-10 | C56, C62, D27, D29.2 |
| ICD-9-CM | 183, 186, 220, 222.0 |
| ICD-O | 9060-9100 |
| eMedicine | med/863 |
| MeSH | D009373 |
A germ cell tumor (GCT) is a neoplasm derived from germ cells. Germ cell tumors can be cancerous or non-cancerous tumors. Germ cells normally occur inside the gonads (ovary and testis). Germ cell tumors that originate outside the gonads may be birth defects resulting from errors during development of the embryo.
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.
Extragonadal germ cell tumors were thought initially to be isolated metastases from an undetected primary tumor in a gonad, but it is now known that many germ cell tumors are congenital and originate outside the gonads. The most notable of these is sacrococcygeal teratoma, the single most common tumor diagnosed in babies at birth.
Of all anterior mediastinal tumors, 15-20% are germ cell tumors of which approximately 50% are benign teratomas.
Germ cell tumors are classified by their histology, regardless of location in the body.
Germ cell tumors are broadly divided in two classes:
The two classes reflect an important clinical difference. Compared to germinomatous tumors, nongerminomatous tumors tend to grow faster, have an earlier mean age at time of diagnosis (~25 years versus ~35 years, in the case of testicular cancers), and have a lower 5 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.
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