系统性肥大细胞增多症（SM）是一种罕见的骨髓增殖性肿瘤，其特征是克隆性肥大细胞异常增殖和浸润不同组织。肥大细胞不受控制的增殖和激活触发血管活性和炎症介质的释放，导致一系列全身症状。大约 95% 的 SM 源自 KIT 基因的功能获得性突变，特别是密码子 816，这凸显了其在 SM 中的重要作用，并使其成为有吸引力的治疗靶点。尽管 KIT 阴性 SM 极为罕见，但文献中记录的病例数量不断增加，使其成为这种疾病的一个有趣的方面。已报道的 KIT 阴性 SM 临床表现差异很大，但许多与 KIT 阳性 SM 相似。 KIT 靶向治疗方案已经改变了 KIT 阳性 SM 的游戏规则，但它们在 KIT 阴性 SM 中的作用仍然存在争议。本报告旨在通过介绍两例 KIT 阴性 SM 病例（其中一例对 KIT 靶向治疗有反应）并分析现有文献中报道的病例，旨在进一步了解 KIT 阴性 SM。版权所有 2024，Alyamany 等人。

Systemic mastocytosis (SM) is a rare type of myeloproliferative neoplasm characterized by abnormal proliferation and infiltration of different tissue by clonal mast cells. The uncontrolled proliferation and activation of mast cells trigger the release of vasoactive and inflammatory mediators, resulting in a cascade of systemic symptoms. Around 95% of SM arise from a gain-of-function mutation at the KIT gene, specifically at codon 816, which highlights its essential role in SM and makes it an attractive target for therapy. Although KIT-negative SM is exceptionally rare, the increased number of cases documented in the literature makes it an intriguing dimension of this disorder. The reported clinical manifestations of KIT-negative SM are widely variable, but many are similar to KIT-positive SM. KIT-targeted therapeutic options have been a game-changer in KIT-positive SM, however their role in KIT-negative SM remains controversial. This report aimed to further understand KIT-negative SM by presenting two cases of KIT-negative SM, one of which was responsive to KIT-targeted therapy, and analyzing reported cases in the existing literature.Copyright 2024, Alyamany et al.