目的探讨乳腺原发性腺泡细胞癌(ACCA)的临床病理学特点、免疫表型、特殊染色特征及鉴别诊断。方法对1例乳腺原发性腺泡细胞癌进行分析,观察其组织学、免疫组化及特殊染色特征,并复习相关文献,探讨其临床病理学特征及预后。结果癌组织由2种细胞构成,一种为大的多边形腺泡样细胞,实性片状排列,细胞界限清楚,胞质丰富呈粗颗粒状,嗜双色性,核呈圆形或卵圆形,染色质稍粗糙,核仁不明显或伴有单个小核仁;另一种为小的闰管样细胞,胞质嗜酸性、细颗粒状,核圆形,核仁不明显或伴单个小核仁;腺泡样细胞和闰管样细胞之间有移行,肿瘤细胞核分裂象少见。免疫组化:CK、α-抗糜蛋白酶和EMA(+),溶菌酶、ER、PR和HER-2(-);PAS染色(抗淀粉酶后)(+)。结论乳腺腺泡细胞癌罕见,但具有特异的组织学特征和免疫表型,需要与乳腺分泌性癌、伴大汗腺分化的癌、富于脂质的癌和颗粒细胞瘤等相鉴别。该肿瘤有一定的复发及转移率,术后需密切随诊。 Objective To investigate the clinicopathological features, immunophenotypes, special staining features and differential diagnosis of primary acinar cell carcinoma of the breast (ACCA). Methods One case of primary acinar cell carcinoma of the breast was analyzed. The histological, immunohistochemical and special staining characteristics were observed. Relevant literatures were reviewed to explore the clinicopathological characteristics and prognosis. Results The cancerous tissue consisted of two kinds of cells, one was a large polygonal acinar-like cell, which was arranged in a solid sheet shape with clear cell boundaries and abundant cytoplasm with coarse granularity, hyperchromaticity and round or oval nucleus , A little rough chromatin, nucleolus is not obvious or accompanied by a single small nucleolus; the other is a small intercalated tube-like cells, cytoplasm eosinophilic, fine granular, nuclear round, nucleolus is not obvious or with a single small Nucleolus; acinar-like cells and between the intercostal tube-like cell migration, rare as mitosis of tumor cells. Immunohistochemistry: CK, alpha-antichymotrypsin and EMA (+), lysozyme, ER, PR and HER-2 (-); PAS staining (after antiamylase) (+). Conclusions Breast acinar cell carcinoma is rare, but has specific histological features and immunophenotypes. It needs differentiating from breast secreting carcinoma, cancer with apocrine gland differentiation, lipid-rich carcinoma and granulosa cell tumor. The tumor has a certain recurrence and metastasis rate, follow-up should be closely followed.