Abstract：
Primary erythromelalgia (PEM) is a rare condition characterized by severe burning pain, erythema, and increased temperature in the extremeties. Mutations in the Nav1.7 sodium channel encoded by the SCN9A are responsible for PEM. The pathophysiology of PEM is unclear, but the involvement of neurogenic and vasogenic mechanisms has been suggested. Here we report a case of severe PEM in a 9-year-old child with a novel SCN9A mutation and examine the distribution of nerve fibers and expression of neuropeptides in the affected skin. Gene mutation analysis revealed a novel mutation p.L951I (c.2851C>A) in the heterozygous form of the SCN9A. An immunofluorescence study showed that intraepidermal nerve fibers were decreased in the affected leg, suggesting small fiber neuropathy. There was no increase in the expression of substance P (SP) or calcitonin gene-related peptide (CGRP) in the lesional skin tissue. These findings suggest SP and CGRP do not play a major role in the pathophysiology of primary erythromelalgia.
摘要：
原发性红血病（PEM）是一种罕见的疾病，其特征是严重的灼热疼痛，红斑,极端温度升高。由SCN9A编码的Nav1.7钠通道中的突变是PEM的原因。PEM的病理生理学尚不清楚，但是已经提出了神经源性和血管生成机制的参与。在这里，我们报告了一个9岁儿童的严重PEM病例，该儿童具有新型SCN9A突变，并检查了受影响皮肤中神经纤维的分布和神经肽的表达。基因突变分析揭示了SCN9A的杂合形式中的新突变p.L951I(c.2851C>A)。免疫荧光研究表明，受影响的腿部表皮内神经纤维减少，提示小纤维神经病变.皮损组织中P物质（SP）或降钙素基因相关肽（CGRP）的表达没有增加。这些发现表明SP和CGRP在原发性红斑痛的病理生理学中不发挥主要作用。
