The incidence of synchronous bilateral infiltrating breast cancer has been reported to be 2%. However, synchronous unilateral infiltrating ductal carcinoma and infiltrating lobular carcinoma (ILC) are very rarely reported. We present a woman with palpable ILC who was later found to have synchronous well-circumscribed ductal carcinoma on further imaging. We also discuss the use of diagnostic approaches such as ultrasonography, mammography and histopathology. This case highlights the importance of careful assessment of concurrent lesions in the breast in the presence of an existing carcinoma.