Objective:　Cases　of　phyllodes　tumors　(PTs)　of　the　breast　with　a　malignant　epithelial　component　are　rare.　The　pathogenesis　and　optimal　treatment　of　patients　with　carcinoma　within　PT　are　still　not　clear.　Methods:　We　collected　five　cases　of　carcinoma　arising　within　PT　of　the　breast　between　2007　and　2018,　and　performed　morphological　observations　and　immunohistochemistry　using　the　EnVision　method.　Results:　Four　cases　arose　from　benign　PT,　including　two　cases　of　low-grade　ductal　carcinoma　in　situ　(DCIS),　and　two　cases　from　classical　lobular　carcinoma　in　situ　(LCIS).　One　case　with　squamous　cell　carcinoma　(SCC)　arose　from　malignant　PT.　Immunohistochemistry　revealed　that　the　LCIS　and　DCIS　cases　were　diffusely　positive　for　ER　and　PR,　while　the　single　case　of　SCC　was　negative.　After　15-64　months　of　follow-up,　all　patients　were　alive.　Conclusion:To　date,　there　has　been　no　standard　treatment　for　this　disease.　Thorough　sampling　is　needed　to　avoid　a　missed　diagnosis.　Sentinel　lymph　node　biopsy　should　be　performed　if　invasive　cancer　is　present.