Pathology:
Pleomorphic xanthoastrocytomas are histologically WHO grade II.
Macroscopic Features:
- Generally superficial tumors attached to meninges.
- Frequently are cystic or forms a mural nodule in the cyst wall.
- Tumor may have an orange hue.
- Tumor firmer than adjacent brain tissue.
Microscopic Features:
- Tumor cells are histologically variable. The tumor cells may be spindled, polygonal, mononuclear or multinucleated, and show marked variation.
- Cytoplasmic lipidization in tumor cells.
- Intranuclear inclusions are frequent.
- Eosinophilic granular bodies are present.
- Abundant reticulin fibers in the tumor which surrounds individual cells or groups of cells.
The slide below shows a pleomorphic xanthoastrocytoma with leptomeningeal involvement (bottom left).
The slide below shows a pleomorphic xanthoastrocytoma with variablility in tumor cell and nuclear size, lipidized cells and granular bodies.
Clinical Characteristics of Pleomorphic Xanthoastrocytoma (PXA):
Most Common Patient Age |
Late childhood/ adolescence |
Most Common Tumor Location |
Cerebral hemispheres |
Growth |
May infiltrate overlying meninges |
Histology |
Cellular pleomorphism Rarely have mitotic figures No necrosis No microvascular proliferation GFAP-reactive |
Special Features |
Previously identified as JPAs, designated as a subtype within last 25 years |
Prognosis |
Good prognosis Surgical cure possible |
These tumors may be cured by surgical resection and have a better prognosis than fibrillary astrocytomas. However:
- Tumor progression to anaplastic astrocytoma and glioblastoma forms has been described especially after radiotherapy treatment.
Malignant transformation of other low-grade astrocytomas occurs in less than 5% of cases. Once the tumor has progressed to a malignant form, it has a significantly worse prognosis.
If complete surgical resection is not feasible, radiation or chemotherapy may help with local control.
