Consecutive histological changes in an astroblastoma that disseminated to the spinal cord after repeated intracranial recurrences: a case report.

A 17-year-old male patient underwent surgery five times (four consecutive intracranial tumor removal surgeries and a final spinal tumor removal surgery). After the third surgery, this case was reported as a low-grade astroblastoma that is characterized by perivascular pseudorosettes consisting of elongated tumor cells arranged around the blood vessels. However, the fourth and fifth surgical specimens demonstrated very interesting histological changes in the astroblastoma. Through the course of relapses, the constituent cells of the astroblastic perivascular rosettes became smaller and rounder, and a multilayered cell arrangement was observed. The nucleus-to-cytoplasm ratio increased, and the compact intervascular cells ultimately lost glial fibrillary acidic protein (GFAP) expression. These undifferentiated cells showed high MIB-1 indices and an increased olig2 index. On the other hand, the cells in all the surgical specimens were positive for certain neuronal markers such as NSE, TUJ1, and nestin. Some astroblastomas may be more immature than the usual astrocytes; however, it is necessary to study more cases to confirm this.