Germ cell tumor


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, , , | ICD9 = , , , | ICDO = 9060-9100 | Image = | Caption = | OMIM = | OMIM_mult = | MedlinePlus = | eMedicineSubj = med | eMedicineTopic = 863 | DiseasesDB = |Germ cell tumor (GCT) is a tumor (neoplasm) derived from germ cells. (Germ cells themselves are not pathogenic; i.e., they are not the viral and bacterial "germs" that cause illness.) Germ cell tumors can occur both inside and outside of the gonads (ovary and testis).

Etiology

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.

Classification

Germ cell tumors are classified by their histology, free full text regardless of location in the body.Germ cell tumors are broadly divided in two classes:
  • The germinomatous or seminomatous germ cell tumors (GGCT, SGCT) include only germinoma and its synonyms dysgerminoma and seminoma.
  • The nongerminomatous or nonseminomatous germ cell tumors (NGGCT, NSGCT) include all other germ cell tumors, pure and mixed.
  • 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 exquisitely sensitive to radiation, and they also respond well to chemotherapy. The prognosis for nongerminomatous has improved dramatically, however, due to the use of platinum-based chemotherapy regimens.Robbins, Basic Pathology; ISBN 0-7216-9274-5, 7th edition, pg 664.Teratocarcinoma is an old name for a germ cell tumor that is a mixture of teratoma and embryonal carcinoma. In more modern usage, this kind of mixed germ cell tumor may be known as a teratoma with elements of embryonal carcinoma, or simply as an embryonal carcinoma.

    Location

    Despite their name, germ cell tumors occur both within and outside the ovary and testis.
  • head
  • inside the cranium — pineal and suprasellar locations are most commonly reported
  • inside the mouth — a fairly common location for teratoma
  • neck
  • 1% to 5% in the mediastinum (mediastinal germ cell tumor)
  • pelvis, particularly sacrococcygeal teratoma
  • ovary
  • testis
  • In females, germ cell tumors account for 30% of ovarian tumors, but only 1 to 3% of ovarian cancers in North America. In younger women germ cell tumors 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, germ cell tumors of the testis occur typically after puberty and are malignant (testicular cancer). In neonates, infants, and children younger than 4 years, the majority of germ cell tumors are sacrococcygeal teratomas. Persons with Klinefelter's syndrome have a 50 times greater risk of germ cell tumors (GSTs)Mediastinal germ cell tumor in a child with precocious puberty and Klinefelter syndrome. Gregory G. Bebb, Frederic W. Grannis, Jr, Isaac B. Paz, Marilyn L. Slovak, Robert Chilcote. Ann Thorac Surg 1998;66:547-548. Abstract. In these persons, GSTs usually contain nonseminomatous elements, present at an earlier age, and seldom are gonadal in location.

    Prognosis

    The 1997 International Germ Cell Consensus ClassificationInternational Germ Cell Consensus Classification: a prognostic factor-based staging system for metastatic germ cell cancers. International Germ Cell Cancer Collaborative Group. J Clin Oncol. 1997 Feb;15(2):594-603 PubMed abstract is a tool for estimating the risk of relapse after treatment of malignant germ cell tumor.A small study of ovarian tumors in girls 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.

    Research

    Germ cell tumors of children are the subject of clinical research by the worldwide Children's Oncology Group (COG), in a number of studies coordinated by Dr. John Cullen, MD.CureSearch.org press release re Germ Cell CancerIntracranial Germ Cell Tumors have been studied through the International CNS GCT Study Group. Under the direction of Jonathan Finlay, the program director, three international treatment studies have been initiated since 1990 with the goal to maintain a high rate of cure while minimizing the late effects of treatment.


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