Anaplastic gangliogliomas of the spinal cord: a scoping review of the literature

Abstract

Gangliogliomas (GGs) are rare, usually low-grade tumors that account for 1–2% of all central nervous system (CNS) neoplasms. Spinal GGs are exceedingly rare (1% of all spinal tumors) and the presentation of anaplastic features in them is even rarer. According to the last World Health Organization (WHO) classification of CNS neoplasms, anaplastic GG (AGG) is classified as a malignant neoplasm (grade III). We performed a scoping review of the literature to elucidate the epidemiology, clinical features, histopathology, treatment, and outcome of primary spinal AGGs, which, to the best of our knowledge, is the first such review. Relevant studies were identified by a search of the MEDLINE and SCOPUS databases, using the following combination of search strings: (anaplastic ganglioglioma or malignant ganglioglioma or high grade ganglioglioma) AND (spine or spinal or spinal cord). We included studies related to primary or recurrent AGGs and malignant transformation of low-grade GGs. The search produced 15 eligible studies, plus two studies from the references, all of which were case reports of patients with spinal AGGs (17 studies with 22 patients). The mean age of the patients was 21.4 years and the sex ratio was 1:1, with male predominance. Motor impairment was the most common presentation, followed by sensory impairment, gait problems, urinary disturbances, and back pain. The thoracic spine was the most frequently involved area (14/22) followed by the cervical (6/22) and lumbar (5/22) spine. In terms of histology, the anaplastic features were usually predominant in the glial element, resembling high-grade astrocytomas, while the neuronal element was composed of the so-called dysplastic ganglion (neuronal) synaptophysin-positive cells, without mitotic figures. Complete surgical resection of the tumor without neurological compromise, plus adjuvant chemotherapy and radiotherapy, was the treatment protocol implemented in the two patients with the best outcome. Primary spinal AGG is an exceedingly rare entity, with only 22 cases being retrieved after an extensive literature search. They appear to affect children and young adults and tend to manifest aggressive behavior. Most studies report that only the glial component of AGGs presents high-grade malignant features, with low mitotic activity in the neuronal component. We therefore suggest that, pending novel targeted therapy, AGGs should be treated as high-grade gliomas, with an aggressive treatment protocol consisting of maximal safe resection and adjuvant chemotherapy and radiotherapy.