Mature Teratomas
Immature Teratomas
Malignant Germ Cell Tumors

The childhood extracranial germ cell tumors comprise a variety of histologic diagnoses and can be broadly classified into mature or immature teratomas and malignant germ cell tumors.

Mature teratomas generally occur in the ovary or at extragonadal locations and are the most common histological subtype of childhood germ cell tumor.[1-3] These teratomas usually contain well-differentiated tissues from the ectodermal, mesodermal, and endodermal germ cell layers, and any tissue type may be found among the tumor. Mature teratomas are benign, though some mature and immature teratomas may secrete enzymes or hormones, including insulin, growth hormone, androgens, prolactin, and vasopressin.[4-6]

Immature teratomas also contain tissues from all three germ cell layers, but immature tissues, primarily neuroepithelial, are present. Immature teratomas can be graded from 0 to 3 based on the amount of immature tissue found in the tumor specimen.[7] Tumors of higher grade are more likely to have foci of yolk sac tumor.[8] Immature teratomas occur primarily in young children at extragonadal sites and in the ovaries of girls near the age of puberty, but there is no correlation between tumor grade and patient age.[8,9]

Malignant germ cell tumors usually contain frankly malignant tissues of germ cell origin (i.e., yolk sac tumors, germinomas, embryonal carcinomas, or choriocarcinomas) or rarely, tissues of somatic origin. Isolated malignant elements may constitute a small fraction of a predominantly immature teratoma.[9,10] Malignant germ cell tumors can broadly be divided into two types: seminomatous (i.e., germinomas, seminomas, or dysgerminomas) and nonseminomatous tumors (i.e., embryonal carcinomas, teratomas, yolk sac tumors, or choriocarcinomas). Yolk sac tumors produce alpha-fetoprotein (AFP), while germinomas, and especially choriocarcinomas, produce beta human chorionic gonadotropin, resulting in the elevated serum levels of these substances. Most children with malignant germ cell tumors will have a component of yolk sac tumor and have elevations of AFP,[11,12] which is serially monitored during treatment to help assess response to therapy.[9-11]

Adolescents and young adults have a higher incidence of seminomatous tumors (testicular and mediastinal seminomas in males and ovarian dysgerminomas in females) than younger patients. Seminomatous tumors are more sensitive to radiation therapy, and thus the distinction is important. Tumors found to have both seminomatous and nonseminomatous elements (embryonal carcinoma is more commonly identified in adolescent testicular tumors) or seminomatous histology associated with elevated serum AFP levels are usually treated as nonseminomas. Patients with nonseminomatous germ cell tumors currently receive the same therapy, regardless of their histologic diagnosis.

References

1. Göbel U, Calaminus G, Engert J, et al.: Teratomas in infancy and childhood. Med Pediatr Oncol 31 (1): 8-15, 1998.  [PUBMED Abstract]
   
   
2. Rescorla FJ: Pediatric germ cell tumors. Semin Surg Oncol 16 (2): 144-58, 1999.  [PUBMED Abstract]
   
   
3. Harms D, Zahn S, Göbel U, et al.: Pathology and molecular biology of teratomas in childhood and adolescence. Klin Padiatr 218 (6): 296-302, 2006 Nov-Dec.  [PUBMED Abstract]
   
   
4. Tomlinson MW, Alaverdian AA, Alaverdian V: Testosterone-producing benign cystic teratoma with virilism. A case report. J Reprod Med 41 (12): 924-6, 1996.  [PUBMED Abstract]
   
   
5. Lam SK, Cheung LP: Inappropriate ADH secretion due to immature ovarian teratoma. Aust N Z J Obstet Gynaecol 36 (1): 104-5, 1996.  [PUBMED Abstract]
   
   
6. Kallis P, Treasure T, Holmes SJ, et al.: Exocrine pancreatic function in mediastinal teratomata: an aid to preoperative diagnosis? Ann Thorac Surg 54 (4): 741-3, 1992.  [PUBMED Abstract]
   
   
7. Norris HJ, Zirkin HJ, Benson WL: Immature (malignant) teratoma of the ovary: a clinical and pathologic study of 58 cases. Cancer 37 (5): 2359-72, 1976.  [PUBMED Abstract]
   
   
8. Heifetz SA, Cushing B, Giller R, et al.: Immature teratomas in children: pathologic considerations: a report from the combined Pediatric Oncology Group/Children's Cancer Group. Am J Surg Pathol 22 (9): 1115-24, 1998.  [PUBMED Abstract]
   
   
9. Marina NM, Cushing B, Giller R, et al.: Complete surgical excision is effective treatment for children with immature teratomas with or without malignant elements: A Pediatric Oncology Group/Children's Cancer Group Intergroup Study. J Clin Oncol 17 (7): 2137-43, 1999.  [PUBMED Abstract]
   
   
10. Göbel U, Calaminus G, Schneider DT, et al.: The malignant potential of teratomas in infancy and childhood: the MAKEI experiences in non-testicular teratoma and implications for a new protocol. Klin Padiatr 218 (6): 309-14, 2006 Nov-Dec.  [PUBMED Abstract]
    
    
11. Mann JR, Raafat F, Robinson K, et al.: The United Kingdom Children's Cancer Study Group's second germ cell tumor study: carboplatin, etoposide, and bleomycin are effective treatment for children with malignant extracranial germ cell tumors, with acceptable toxicity. J Clin Oncol 18 (22): 3809-18, 2000.  [PUBMED Abstract]
    
    
12. Marina N, Fontanesi J, Kun L, et al.: Treatment of childhood germ cell tumors. Review of the St. Jude experience from 1979 to 1988. Cancer 70 (10): 2568-75, 1992.  [PUBMED Abstract]