Liu Bella Lingjia, Mehrotra Meenakshi, Kowtha Lakshmi, Guan Michelle, Houldsworth Jane, Baskovich Brett, Harigopal Malini
Department of Pathology, Molecular and Cell-Based Medicine, Icahn School of Medicine at Mount Sinai, New York City, NY, USA.
Int J Surg Pathol. 2025 Feb;33(1):220-228. doi: 10.1177/10668969241256112. Epub 2024 Jun 5.
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.
叶状肿瘤是一种罕见的乳腺纤维上皮性肿瘤，主要见于中年患者，呈现从良性到恶性的形态学连续谱。青少年乳头状瘤病是一种罕见的良性增生性乳腺肿瘤，主要影响年轻个体，且后续发生乳腺癌的风险可能升高。青少年纤维腺瘤是一种边界清晰的双相性肿瘤，常发生于青春期女孩，其特征为具有普通型上皮增生的围管性生长模式和类似男性乳腺增生的微乳头增生。在此，我们报告一例不寻常的病例，一名26岁女性左乳房外下象限可触及肿块。超声检查发现一个5.9厘米的分叶状低回声实性肿块，伴有散在小囊肿。术前活检最初诊断为纤维上皮性病变，鉴别诊断考虑巨大细胞纤维腺瘤和叶状肿瘤。随后的完整切除显示，良性叶状肿瘤特征区域与独特成分紧密混合，如突出的多个囊肿表现为大汗腺化生和乳头状大汗腺化生、导管乳头状瘤病以及青少年乳头状瘤病特有的导管淤滞，还有增生的导管上皮伴有微乳头突起，呈现围管性生长模式，提示青少年纤维腺瘤。最终诊断为具有良性叶状肿瘤、青少年乳头状瘤病和青少年纤维腺瘤联合特征的纤维上皮性病变。进一步调查发现有乳腺癌家族史。分子分析揭示了这些不同组织病理学区域内独特且重叠的突变模式。本文首次在文献中描述了这种单个肿瘤内具有混合特征的不寻常表现以及各个成分的分子特征。
