From the Guidelines
Immature teratoma histology is characterized by the presence of immature or embryonal-appearing neural tissue, with varying degrees of differentiation, and tissue from all three germ layers, including endoderm, mesoderm, and ectoderm. The histological features of immature teratoma include primitive neuroectodermal elements, such as primitive neural tubules, rosettes, and immature neuroepithelium, alongside more mature elements like skin, cartilage, respiratory epithelium, and intestinal tissue 1. The amount of immature neural tissue determines the grade of the tumor, with higher grades containing more immature elements, and this grading is prognostically relevant 1. The immature components often appear as small, densely packed cells with hyperchromatic nuclei and high nuclear-to-cytoplasmic ratios, and mitotic figures are frequently present, reflecting the tumor's proliferative nature.
Some key features of immature teratoma histology include:
- Presence of tissue from all three germ layers (endoderm, mesoderm, and ectoderm)
- Immature or embryonal-appearing neural tissue
- Primitive neuroectodermal elements, such as primitive neural tubules, rosettes, and immature neuroepithelium
- Mature elements like skin, cartilage, respiratory epithelium, and intestinal tissue
- Cellular atypia and disorganized tissue architecture
- High nuclear-to-cytoplasmic ratios and frequent mitotic figures in immature components.
The World Health Organization (WHO) classification of germ cell tumors, including immature teratomas, provides a framework for understanding the histological features and prognostic implications of these tumors 1. Overall, the histological appearance of immature teratoma correlates with the tumor's more aggressive biological behavior, particularly in higher-grade lesions, which have greater malignant potential and require more aggressive treatment approaches.
From the Research
Histology of Immature Teratoma
The histology of immature teratoma is characterized by the presence of immature tissue elements, in addition to mature components, which are derived from the three germ cell layers: ectoderm, mesoderm, and endoderm.
- The immature tissue elements can be identified as neurotubules or rosettes, which are indicative of primitive neuroectodermal differentiation 2.
- The proportion of immature tissue elements defines the grade of immaturity, with four grades defined in the WHO classification: Grade 0 (mature teratoma), Grade 1, Grade 2, and Grade 3 (the highest grade of immaturity) 2, 3.
- Immature teratomas can also contain foci of yolk sac tumor (YST), which is an important factor in determining the prognosis and treatment of the patient 2, 3.
Key Features
- Immature teratomas are malignant ovarian tumors that contain a mixture of mature and immature tissue elements 2, 4.
- The histology of immature teratoma can include areas of mature teratoma tissues derived from the ectodermal and mesodermal lineages, as well as areas of immature teratoma tissue composed of small undifferentiated cells with primitive neuroectodermal differentiation foci forming neuroepithelial elements 5.
- The diagnosis of immature teratoma is based on the histological examination of the tumor tissue, which can be classified as mature or immature depending on the degree of differentiation of its components 6.