The World Health Organization (WHO) diagnostic criteria for malignant phyllodes tumor (MPT) may miss a significant number of MPTs with metastatic potential. New refined diagnostic criteria (Refined Criteria) for MPT were recently proposed. The aim of this study is to validate the Refined Criteria. This validation study included 136 borderline (borderline phyllodes tumor [BoPT]) and MPT cases that were not included in the initial study. We evaluated tumor classifications based on both the Refined Criteria and the WHO criteria. The Refined Criteria defines MPT when these criteria are met (1) stromal overgrowth with ≥ 1 feature(s) of marked stromal cellularity, marked stromal cytologic atypia, or ≥10 mitoses per 10 high-power fields (10 mitoses/10 HPFs) or (2) marked stromal cellularity with ≥1 feature(s) of marked stromal cytologic atypia, ≥10 mitoses/10 HPFs or permeative border. The WHO criteria require all 5 morphologic features (stromal overgrowth, permeative border, marked stromal cellularity, marked stromal cytologic atypia, and ≥10 mitoses/10 HPFs) for an MPT diagnosis. Using the Refined Criteria, none of the 61 BoPTs developed metastasis and 40.0% of the 75 MPTs developed metastases; local recurrence was seen in 11.5% BoPTs and 25.3% MPTs. Using the WHO criteria, 9.6% of the 94 BoPTs developed metastases and 50.0% of the 42 MPTs developed metastases; 14.9% of the BoPTs had local recurrence and 28.6% of the MPTs had local recurrence. Nine (30.0%) of the 30 tumors that developed distant metastases were diagnosed as BoPTs by the WHO criteria. When we combined the 75 MPTs from this validation cohort with the 65 MPT cases from the published data using the Refined Criteria, 50 (35.7%) of the 140 MPTs developed metastases, whereas 8 cases with metastases were <5 cm. In the univariate analysis with log-rank test, stromal overgrowth, marked stromal cellularity, marked stromal cytologic atypia, ≥10 mitoses/10 HPFs, presence of heterologous components other than liposarcomatous component, and presence of stromal necrosis were significantly associated with the risk of metastasis (all with P < 0.05). In multivariate analysis with Cox proportional hazard regression, stromal overgrowth and marked stromal cellularity were significantly associated with metastasis (both with P < 0.001). The Refined Criteria are superior to the WHO criteria in predicting the clinical outcomes of BoPTs and MPTs. Using the Refined Criteria, 35.7% of 140 patients with MPT developed metastases, whereas none (0%) of the patients with BoPT developed metastases. Patients with MPT have a high metastatic rate; these patients may benefit from systemic chemotherapy or targeted therapies. In contrast, patients with BoPT may be managed with complete local excision alone without chemotherapy.

中文翻译：

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新提出的恶性叶状肿瘤细化诊断标准的验证研究，包括 136 例交界性和恶性叶状肿瘤病例。


世界卫生组织 (WHO) 恶性叶状肿瘤 (MPT) 的诊断标准可能会漏掉大量具有转移潜力的 MPT。最近提出了新的 MPT 细化诊断标准（Refined Criteria）。本研究的目的是验证细化标准。该验证研究包括 136 例未纳入初始研究的交界性（交界性叶状肿瘤 [BoPT]）和 MPT 病例。我们根据细化标准和世界卫生组织标准评估了肿瘤分类。当满足这些标准时，精炼标准定义为 MPT (1) 间质过度生长，具有 ≥ 1 个显着基质细胞性特征、显着基质细胞异型性，或每 10 个高倍视野≥10 个有丝分裂（10 个有丝分裂/10 个 HPF），或(2) 明显的基质细胞结构，具有≥1个明显的基质细胞异型性特征、≥10个有丝分裂/10个HPF或渗透性边界。 WHO 标准要求 MPT 诊断具备所有 5 个形态学特征（间质过度生长、渗透性边界、显着的间质细胞结构、显着的间质细胞异型性和 ≥10 个有丝分裂/10 个 HPF）。使用细化标准，61 个 BoPT 均未发生转移，75 个 MPT 中有 40.0% 发生转移； 11.5% BoPT 和 25.3% MPT 出现局部复发。根据世界卫生组织的标准，94个BoPT中的9.6%发生了转移，42个MPT中的50.0%发生了转移； 14.9%的BoPT有局部复发，28.6%的MPT有局部复发。根据 WHO 标准，发生远处转移的 30 个肿瘤中有 9 个（30.0%）被诊断为 BoPT。当我们使用精炼标准将该验证队列中的 75 个 MPT 与已发表数据中的 65 个 MPT 病例合并时，140 个 MPT 中有 50 个 (35.7%) 出现转移，而 8 个转移病例<5 cm。 在对数秩检验的单变量分析中，间质过度生长、显着的间质细胞结构、显着的间质细胞学异型性、≥10个有丝分裂/10个HPF、除脂肪肉瘤成分之外的异源成分的存在以及间质坏死的存在与以下风险显着相关：转移（均 P < 0.05）。在 Cox 比例风险回归的多变量分析中，基质过度生长和显着的基质细胞结构与转移显着相关（均 P < 0.001）。细化标准在预测 BoPT 和 MPT 临床结果方面优于 WHO 标准。使用细化标准，140 名 MPT 患者中有 35.7% 发生转移，而 BoPT 患者中没有 (0%) 发生转移。 MPT患者转移率高；这些患者可能受益于全身化疗或靶向治疗。相比之下，BoPT 患者可以仅通过完全局部切除进行治疗，无需化疗。