Abstract：
Phyllodes tumor is an uncommon breast fibroepithelial neoplasm mainly found in middle-aged patients, presenting a morphologic continuum from benign to malignant. Juvenile papillomatosis represents a rare benign proliferative breast tumor primarily affecting young individuals and carries a potential elevated risk of subsequent breast cancer development. Juvenile fibroadenoma is a well-circumscribed biphasic neoplasm that often occurs in adolescent girls, characterized by a pericanalicular growth pattern with usual-type epithelial hyperplasia and gynaecomastia-like micropapillary proliferation. Herein, we present an unusual example of a 26-year-old woman with a left breast outer lower quadrant palpable mass. Ultrasonography identified a 5.9 cm lobulated hypoechoic solid mass with scattered small cysts. The preoperative biopsy initially diagnosed a fibroepithelial lesion, considering giant cellular fibroadenoma and phyllodes tumor in the differential. Subsequent complete excision revealed areas of benign phyllodes tumor features closely admixed with distinctive elements such as prominent multiple cysts exhibiting apocrine and papillary apocrine metaplasia, duct papillomatosis, and duct stasis characteristic of juvenile papillomatosis, and hyperplastic ductal epithelium with micropapillary projections demonstrating a pericanalicular growth pattern indicative of juvenile fibroadenoma. The diagnosis was conclusively established as a fibroepithelial lesion with combined features of benign phyllodes tumor, juvenile papillomatosis, and juvenile fibroadenoma. Further investigation uncovered a family history of breast cancer. Molecular analysis revealed a pattern of unique and overlapping mutations within these distinct histopathological areas. This unusual presentation with hybrid features within a single tumor is described for the first time in the literature along with the molecular signature of the individual components.
摘要：
叶状肿瘤是一种罕见的乳腺纤维上皮肿瘤，主要见于中年患者，呈现从良性到恶性的形态学连续体。青少年乳头状瘤病代表一种罕见的良性增生性乳腺肿瘤，主要影响年轻人，并具有随后发生乳腺癌的潜在高风险。青少年纤维腺瘤是一种界限清楚的双相肿瘤，通常发生在青春期女孩中，表现为窦周生长模式，伴有普通型上皮增生和妇科乳房发育样微乳头状增生。在这里，我们提供了一个不寻常的例子，一个26岁的女性，左乳房外下象限可触及肿块。超声检查发现5.9cm分叶状低回声实性肿块，散见小囊肿。术前活检最初诊断为纤维上皮病变，考虑巨大细胞纤维腺瘤和叶状肿瘤的差异。随后的完全切除显示良性叶状肿瘤的特征区域与独特的元素紧密混合，例如突出的多发性囊肿，表现出顶腺和乳头状顶腺的上皮化生，导管乳头状瘤病,和青少年乳头状瘤病的导管淤滞特征，和增生的导管上皮，具有微乳头状突起，表明膜周生长模式表明青少年纤维腺瘤。最终诊断为纤维上皮病变，并伴有良性叶状肿瘤的特征。青少年乳头状瘤病，和青少年纤维腺瘤.进一步的调查发现了乳腺癌的家族史。分子分析揭示了在这些不同的组织病理学区域内独特和重叠的突变模式。在文献中首次描述了这种在单个肿瘤中具有混合特征的不寻常表现以及单个成分的分子特征。
