[Pathology of Crow-Fukase syndrome]

Although the exact mechanisms underlying peripheral neuropathy in Crow-Fukase syndrome (CFS), also known as POEMS syndrome, remain obscure, careful scrutiny of the pathological changes in the peripheral nervous system (PNS) and systemic organs by using biopsy and autopsy materials may provide useful information regarding the pathogenesis and future therapeutics of the syndrome. In this review, previous biopsy/autopsy studies on CFS were systematically reviewed and the details of the pathological changes in the PNS and vascular system were noted. Most biopsied nerves revealed the characteristics of axonal degeneration and demyelination together; however, the nerve roots obtained at autopsy showed massive demyelination with few axonal changes. This morphological discrepancy can be interpreted as primary demyelination in the proximal PNS and secondary axonal degeneration in the distal PNS. Another histological hallmark of the syndrome is edema in the endoneurial space. Changes in the endoneurial and epineurial microvessels, including hyperplasia of endothelial cells, were occasionally observed. Endoneurial edema and microvascular changes can be attributed to the high serum concentration of vascular endothelial growth factor in this disorder, and the derangement in endoneurial homeostasis due to impaired blood-nerve barrier can be considered a possible pathomechanism underlying peripheral neuropathy in the CFS.