Background

Patients with mast cell (MC) activation symptoms and elevated baseline serum tryptase level (MCAS-T) may not necessarily have a clonal MC disorder. Many are diagnosed with hereditary α-tryptasemia (HαT), a genetic trait characterized by autosomal dominant inheritance of multiple copies of TPSAB1 encoding α-tryptase and increased risk for severe anaphylaxis.

Objective

The aim of our study was to identify and characterize bone marrow MC histopathologic features specific for MCAS-T.

Methods

A total of 43 patients with MCAS-T underwent evaluation, including bone marrow biopsy, for a MC disorder. The results of the work-up for clonal MC disorders such as systemic mastocytosis and monoclonal MC activation syndrome were negative. Bone marrow MC histopathology was reviewed to identify characteristic features of MCAS-T. A subgroup of patients was available for tryptase genotyping.

Results

Patients with MCAS-T showed unique morphologic and histologic features when compared with controls. MCs were larger (P < .01), hypogranular (P < .01), frequently detected in paratrabecular (P < .05) and perivascular (P < .01) locations, and associated with bone marrow eosinophilia (P < .01). A total of 10 patients who were available for tryptase genotyping were all confirmed to have HαT. This subgroup was representative of the larger MCAS-T cohort.

Conclusion

We report unique bone marrow MC phenotypic and histopathologic changes in patients with MCAS-T. These morphologic changes are associated with an elevated tryptase level that has been confirmed to be caused by HαT in all patients available for testing.

中文翻译：

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有肥大细胞活化症状和基线血清类胰蛋白酶水平升高的患者具有独特的骨髓形态

背景

具有肥大细胞 (MC) 激活症状和基线血清类胰蛋白酶水平 (MCAS-T) 升高的患者可能不一定患有克隆性 MC 疾病。许多人被诊断出患有遗传性 α-类胰蛋白酶 (HαT)，这是一种遗传特征，其特征是常染色体显性遗传多拷贝TPSAB1编码 α-类胰蛋白酶，并且会增加严重过敏反应的风险。

客观的

我们研究的目的是确定和表征 MCAS-T 特有的骨髓 MC 组织病理学特征。

方法

共有 43 名 MCAS-T 患者接受了 MC 疾病评估，包括骨髓活检。对克隆性 MC 疾病（如系统性肥大细胞增多症和单克隆 MC 激活综合征）的检查结果为阴性。审查骨髓 MC 组织病理学以确定 MCAS-T 的特征。一部分患者可用于类胰蛋白酶基因分型。

结果

与对照组相比，MCAS-T 患者表现出独特的形态学和组织学特征。MC 较大（P  < .01）、颗粒状（P  < .01），经常在小梁旁（P  < .05）和血管周围（P  < .01）位置检测到，并且与骨髓嗜酸性粒细胞增多有关（P  < .01） . 共有 10 名可用于类胰蛋白酶基因分型的患者均被证实患有 HαT。该亚组代表较大的 MCAS-T 队列。

结论

我们报告了 MCAS-T 患者独特的骨髓 MC 表型和组织病理学变化。这些形态学变化与类胰蛋白酶水平升高有关，在所有可供检测的患者中，该水平已被证实是由 HαT 引起的。