恶性增殖性毛发肿瘤（MPPT）是罕见的、独特的皮肤附件肿瘤。 MPPT 中的肉瘤转化更为罕见（之前报道过 4 例）。在这里，我们报告了一名 63 岁男性头皮上发生的 MPPT 肉瘤转化的特殊病例，并提供了深入的分子谱以及组织学、免疫组织化学和后续数据。上皮和肉瘤成分的共同突变包括功能丧失的 TP53 突变。仅在上皮成分中发现了失活 TP53 突变，仅在肉瘤成分中发现了失活 CDKN2A 突变。之前在 MPPT 中报道的拷贝数变异也被鉴定出来，包括 6p21.1 丢失、6q 臂丢失和 15q21.1-q26.3 增益[上皮]，以及 6p22.2-p22.3 丢失[肉瘤]。组织学上，通过免疫组织化学检测，该肿瘤显示出增殖性毛发肿瘤、具有透明细胞变化的癌的并列区域以及未对 AE1/AE3、p40、CD34、S100 蛋白和平滑肌肌动蛋白进行染色的肉瘤区域。患者存活 2 年，没有复发或转移的证据。版权所有 © 2024 Wolters Kluwer Health, Inc. 保留所有权利。

Malignant proliferating pilar tumors (MPPTs) are rare, unique cutaneous adnexal tumors. Sarcomatous transformation in MPPTs is even rarer (4 previous cases reported). Here, we report an extraordinary case of a MPPT with sarcomatous transformation occurring on the scalp of a 63-year-old man with an in-depth molecular profile along with histologic, immunohistochemical, and follow-up data. Shared mutations in the epithelial and sarcomatous components included a loss-of-function TP53 mutation. An inactivating TP53 mutation was only identified in the epithelial component, and an inactivating CDKN2A mutation was only identified in the sarcomatous component. Copy number variations previously reported in MPPT were also identified, including 6p21.1 loss, 6q arm loss, and 15q21.1-q26.3 gain [epithelial], and 6p22.2-p22.3 loss [sarcoma]. Histologically, the tumor demonstrated juxtaposed areas of proliferating pilar tumor, carcinoma with clear cell change, and sarcomatous areas that did not stain for AE1/AE3, p40, CD34, S100 protein, and smooth muscle actin  by immunohistochemistry. The patient is alive at 2 years without evidence of recurrence or metastasis.Copyright © 2024 Wolters Kluwer Health, Inc. All rights reserved.