Paget's disease of the breast is an uncommon disorder that accounts for 1% to 3% of all mammary tumors. The incidence of underlying carcinoma associated with Paget's disease has been reported in 82% to 100% of cases. The finding of underlying carcinoma reaches almost 100% when a palpable lump is also present. In this rare case, we described a patient presenting with Paget's disease but no palpable lump. However, we found 11 independent regions which were all invasive ductal carcinoma after the operation. Considering this patient, we should pay more attention to a multifocal and multicentric breast carcinoma associated with Paget's disease. Furthermore, we believe the mammography examination and a modified radical mastectomy are the most appropriate treatments for this population in clinical practice.