探讨少见部位转移性乳腺浸润性小叶癌(ILC)的临床病理特征。

回顾性收集2018年1月至2021年12月武汉大学人民医院病理科诊断的少见部位转移性ILC 4例的临床资料，观察其临床特点、组织学形态、免疫组织化学表型及预后。

少见部位转移性ILC 4例，确诊年龄为42～53岁，从确诊ILC到初次转移的间隔时间分别为5、1、11、3年；分别记录了3、3、2、2个不同的转移部位，包括子宫、附件、胃肠道和腹膜；组织学类型包括3例经典型及1例多形性型；转移灶分子分型包括3例Luminal B型及1例三阴性乳腺癌；临床治疗方案为手术＋化疗＋免疫治疗，Luminal B型患者还包括内分泌治疗。

乳腺ILC具有独特的转移模式，当转移至女性生殖系统、消化道及腹膜等器官时，容易误诊为原发肿瘤而导致过度手术治疗，需要充分结合病史及临床病理特征来诊断及鉴别诊断。

To explore the clinicopathological characteristics of invasive lobular carcinoma (ILC) of the breast with metastases to rare sites.

This study collected clinical data of four patients with rare-site metastatic breast ILC diagnosed in the Department of Pathology, Renmin Hospital of Wuhan University from January 2018 to December 2021. Observations were made on their clinical characteristics, histological morphology, immunohistochemical phenotype and prognosis.

The four cases of rare-site metastatic ILC were diagnosed at the age of 42 to 53 years. The intervals from ILC diagnosis to the first metastasis were 5, 1, 11 and 3 years, respectively. Each case had metastases to different locations (3, 3, 2, 2), including the uterus, adnexa, gastrointestinal tract and peritoneum. Histologically, three cases were classified as classic type and one as pleomorphic type. Based on molecular subtypes, there were three cases of luminal B subtypes and one case of triple negative breast cancer. The clinical treatment strategies involved surgery, chemotherapy and immunotherapy, with endocrine therapy also included for patients with luminal B subtypes.

ILC of the breast has a unique pattern of metastasis. When the metastasis occurs on the organs of the female reproductive system, gastrointestinal tract and peritoneum, there is high risk of misdiagnosis as primary tumors, leading to overtreatment with surgery. The clinicians should pay attention to case history and clinicopathological characteristics in order to make an accurate diagnosis and differential diagnosis.