Suprasellar teratoma

Suprasellar teratoma

Mixed density and intensity suprasellar lesion containing fat, calcification and soft tissue. Mild enhancement of solid component after contrast on MRI superimposed on intrinsic T1 hyperintensity.

Totipotent stem cells in an undifferentiated state give rise to embryonal carcinomas. If the stem cells have progressed toward the extraembryonic pathway, the tumors produced are yolk sac tumors or choriocarcinomas. If the cells have progressed toward the embryonic pathway, they become teratomas.

Histopathologic classification of teratomas includes mature, immature, and malignant varieties.

Teratomas contain elements derived from the three germ cell layers: endoderm, mesoderm, and ectoderm.

The etiology and pathogenesis of extragonadal teratomas remain unclear, but they are thought to arise from misplaced primordial germ cells, which become embedded in or near midline structures in the head, mediastinum, or sacrococcygeal region.

The tumor is a rounded, sharply marginated mass in gross appearance. Solid parts composed of histologically varying elements are observed in 81% of tumors. Toothlike calcifications are often seen within the tumor. Calcification is another hallmark of this tumor; however, toothlike or rim calcifications are apparent in only 56% of tumors.

At MR imaging, sebaceous fat within the tumor produces characteristically high signal intensity on T1-weighted images. In addition to the detection of fat, gravity-dependent layering, palm tree–like protrusions and fat-fluid levels are other imaging characteristics of mature cystic teratomas. Malignant transformation of teratomas has also been reported in the mediastinum, stomach, brain, and sacrococcygeal region.

Spectrum of Germ Cell Tumors: From Head to Toe
Teruko Ueno, MD, Yumiko Oishi Tanaka. March 2004 RadioGraphics, 24, 387-404.