Malignant glial tumor arising from the site of a previous hamartoma/ganglioglioma: coincidence or malignant transformation?

Gangliogliomas are generally considered benign tumors. Although more commonly found in the brain, spinal cord ganglioglioma is a well established, albeit infrequent, entity. We describe a 2-decade clinical course of a patient initially diagnosed with a thoracolumbar 'glial-neuronal hamartoma' at age 4. Seventeen years after his first operation, local recurrence was noted. Despite subsequent multiple gross total resections and adjuvant therapy, histologic features became increasingly ominous and ultimately proved fatal. This is an unusual report and histologic presentation of a resected spinal cord ganglioglioma recurring as an anaplastic ependymoma/astrocytoma and subsequently a glioblastoma. It is quite likely that the originally resected ganglioglioma was actually part of a primitive neuroectodermal tumor which had undergone extensive maturation.