对于进行乳房减少术或风险降低乳房切除术的患者来说，隐匿性乳腺癌的发病率分别为1％至约10％。发现偶然癌症通常需要随后进行乳房切除术，因为边界模糊不清。本研究旨在确定接受手术整形乳房保留手术（OBCS）并同时进行对称手术的患者中对侧恶性肿瘤的发病率。作者们回顾了他们机构的前瞻性数据库，该数据库中包含接受OBCS的单侧乳腺癌患者的信息。对于在对侧乳房上进行切除活检的患者，进行了单独的分析。评估了患者人口学特征、病理特征和随后的疾病管理。在2018年3月至2022年7月期间，共有289名患者接受了OBCS和对称手术，其中有100名患者获得了对侧乳房组织标本。对于其中14名患者，在进行对称手术时进行了计划的切除活检，其中5个病变（36％）被发现是恶性的。在其余的86名患者中，92％进行了术前乳房磁共振成像（MRI）。有4名患者（4.7％）在对侧乳房病理学检查中发现了隐匿性恶性肿瘤；其中三名患者为导管内癌症，一名患者为浸润性小叶癌。这三名患者都进行了术前MRI检查，但未发现可疑发现。没有患者需要进行对侧乳房癌的切除术治疗。OBCS对称手术中的隐匿性恶性肿瘤发病率接近5％。切除活检的最终病理学结果的升级率高于以前报道的结果。所有发现的恶性肿瘤为早期病变。这种人群中隐匿性乳腺癌的发病率更高，所以应该常规进行所有标本的定位，这使得患者在发现偶然的早期癌症时可以选择保留乳房的选项。© 2023年。外科肿瘤学协会。

The incidence of occult breast cancer among patients undergoing reduction mammoplasty or risk-reducing mastectomies ranges from 1% to approximately 10%, respectively. Identification of incidental cancer often mandates subsequent mastectomy due to ambiguous margins. This study aimed to determine the incidence of contralateral malignancy among patients undergoing oncoplastic breast-conserving surgery (OBCS) with concurrent symmetry procedures.The authors reviewed their prospectively maintained institutional database of patients with unilateral breast cancer who underwent OBCS. Patients who underwent excisional biopsy on the contralateral breast were analyzed separately. Patient demographics, pathologic features, and subsequent disease management were evaluated.Between March 2018 and July 2022, 289 patients underwent OBCS with a symmetry procedure, and 100 patients yielded contralateral breast tissue specimens. For 14 patients, a planned excisional biopsy was performed with their symmetry procedure, and five lesions (36%) were found to be malignant. Of the remaining 86 patients, 92% underwent preoperative breast magnetic resonance imaging (MRI). Four patients (4.7%) had occult malignancies identified on the contralateral breast pathology; three patients with ductal carcinoma in situ and one patient with invasive lobular carcinoma. Three patients had undergone preoperative MRI without suspicious findings. No patients required mastectomy for treatment of the contralateral breast cancer.The incidence of occult malignancy among OBCS symmetry procedures approaches 5%. The final pathology of excisional biopsies had a higher upgrade rate than previously reported. All identified malignancies were early-stage disease. The higher incidence of occult breast cancer in this population warrants the routine orientation of all specimens, which allows patients with incidental early-stage cancer the option of breast preservation.© 2023. Society of Surgical Oncology.