ST11 附件肿瘤是一种罕见的、最近被描述的与黑斑息肉综合征相关的恶性肿瘤。它主要起源于附件旁软组织，常继发累及输卵管和卵巢。 STK11 附件肿瘤由于其可变的形态和非特异性免疫特征而具有广泛的鉴别诊断，目前诊断确认需要测序来识别 STK11 突变。我们研究了 STK11 (LKB1) 免疫组织化学 (IHC) 在 STK11 附件肿瘤和形态模拟队列中的诊断效用。对 122 个肿瘤进行了 STK11 IHC，其中包括 17 个 STK11 附件肿瘤和 105 个形态模拟（10 个 Wolffian 雌性附件肿瘤）起源，22 例成人颗粒细胞肿瘤，10 例幼年颗粒细胞肿瘤，4 例支持-间质细胞肿瘤，2 例间质细胞肿瘤，1 例支持细胞肿瘤，1 例类固醇细胞肿瘤，4 例卵巢外性索间质肿瘤，16 例卵巢子宫内膜样癌，8例输卵管卵巢高级别浆液性癌，5例卵巢中肾样腺癌，14例卵巢癌肉瘤，5例腹膜恶性间皮瘤，2例盆腔丛状平滑肌瘤和1例卵巢实性假乳头状瘤）。所有 STK11 附件肿瘤均显示 STK11 细胞质染色完全丧失。所有其他肿瘤类型均显示保留的细胞质染色，但一种具有粘液分化的子宫内膜样癌显示 STK11 表达完全缺失，以及一种具有亚克隆缺失的高级别浆液性癌。STK11 是一种高度敏感和特异的免疫组织化学标记物，用于区分 STK11 附件肿瘤和附件肿瘤。它的组织学模拟，并且可以消除在适当的形态学背景下进行验证性分子研究的需要。© 2024 John Wiley

ST11 adnexal tumour is a rare, recently described malignant neoplasm that is associated with Peutz-Jeghers syndrome. It predominantly originates from the para-adnexal soft tissues and often shows secondary involvement of the fallopian tube and ovary. STK11 adnexal tumours have a broad differential diagnosis due to their variable morphology and non-specific immunoprofile, and diagnostic confirmation currently requires sequencing to identify an STK11 mutation. We investigate the diagnostic utility of STK11 (LKB1) immunohistochemistry (IHC) in a cohort of STK11 adnexal tumours and morphological mimics.IHC for STK11 was performed on 122 tumours, including 17 STK11 adnexal tumours and 105 morphological mimics (10 female adnexal tumours of Wolffian origin, 22 adult granulosa cell tumours, 10 juvenile granulosa cell tumours, four Sertoli-Leydig cell tumours, two Leydig cell tumours, one Sertoli cell tumour, one steroid cell tumour, four extra-ovarian sex cord-stromal tumours, 16 ovarian endometrioid carcinomas, eight tubo-ovarian high-grade serous carcinomas, five ovarian mesonephric-like adenocarcinomas, 14 ovarian carcinosarcomas, five peritoneal malignant mesotheliomas, two pelvic plexiform leiomyomata and one ovarian solid pseudopapillary tumour). All STK11 adnexal tumours showed complete loss of cytoplasmic staining for STK11. All other tumour types showed retained cytoplasmic staining, except for one endometrioid carcinoma with mucinous differentiation which showed complete loss of STK11 expression and a high-grade serous carcinoma with subclonal loss.STK11 is a highly sensitive and specific immunohistochemical marker for distinguishing STK11 adnexal tumour from its histological mimics, and can obviate the need for confirmatory molecular studies in the appropriate morphological context.© 2024 John Wiley & Sons Ltd.