In order to investigate the clinical significance of redundant nerve roots of the cauda equina (RNR) and their pathogenesis, the following studies were performed: 1) examination of 1,256 myelograms of patients with lumbar disease; 2) clinical analysis of 55 patients with RNR and 75 without RNR; 3) electrophysiological examination of 9 patients with RNR; and 4) anatomical and histopathological examination of 6 autopsy cases. RNR were found in 42% of patients with severely constricted spinal canals. In comparing patients with RNR and those without RNR, RNR were found in older patients, these patients exhibited a longer period from the onset of the symptoms to the time of myelographic manifestation, and they caused more severe signs and symptoms. The spatial distribution of redundant nerve roots and the extent of degeneration of nerve fibers in redundant nerve roots indicated the close causal relationship between RNR and constriction of the spinal canal. As the pathogenesis of RNR, the authors suggest a squeezing force from the constricted spinal canal acting on the nerve roots.

Purpose of reviewThe present review aims to provide readers with the latest updates on the biology and clinical management of cutaneous angiosarcoma (cAS).Recent findingsThe genomic alteration of cAS is heterogeneous. Mutations are enriched in the mitosis-activated kinase (MAPK) pathway. Functional analysis has identified molecules that may serve as potential markers and therapeutic targets of angiosarcoma. These molecules include survivin, HSP90, FOXM1, miR-497-5p, KCa3.1, and miR210.This body of knowledge has not yet transferred to clinical practice. The mainstay of treatment for cAS remains surgery followed by postoperative radiotherapy. The efficacy of paclitaxel as an adjuvant chemotherapy is suggested.For patients with advanced cAS, paclitaxel is the treatment of choice. There are also second-line treatment options that are supported by evidence of varying strength. A multikinase inhibitor, pazopanib, has been assessed in several studies, most of which support its efficacy for angiosarcoma. Bevacizumab monotherapy may be effective for angiosarcoma. The efficacy of eribulin mesylate and trabectedin for angiosarcoma is currently being assessed. Recent publications highlighted the role of the immune system in the biology of cAS.SummaryFuture research efforts should focus on the following aspects of cAS: drug development directed at recent molecular targets, clinical trials designed specifically for patients with cAS, and the role of immunotherapy for cAS.