Abstract Background The prognosis of ductal carcinoma in situ (DCIS) is reportedly well. Extremely rare patients with DCIS develop distant breast cancer metastasis without locoregional or contralateral recurrence. This is the first report of multiple bones and sigmoid colon metastases from DCIS after mastectomy. Case presentation A 43-year-old woman was diagnosed with DCIS, and she received mastectomy, followed by endocrine therapy and target therapy. During the following-up, convulsions and pain on the legs were complaint. Therefore, Computed Tomography (CT) on bones and positron emission tomography (PET) for whole body were examined in order. Multiple bones and sigmoid colon were under the suspect of metastases, which were then verified by biopsy in the left ilium and colonoscopy respectively. Conclusions This case reveals the heterogeneous behavior and the potential poor outcome of DCIS, regular examination and surveillance are necessary even though the distant metastasis rate in DCIS is low.
