A 25-year-old woman sought a second opinion following initial assessment of a lump in the right breast, which was erroneously diagnosed as a sebaceous cyst. No preliminary investigations such as breast imaging had been undertaken, and the patient was scheduled for excision of the lump under local anesthetic as a day case. At the time of her attendance for surgery it was noted that the breast lesion was clinically more ominous than a simple sebaceous cyst and formal breast assessment was arranged. The lump had been present for approximately two months and had progressively increased in size. There was no fluctuation in size with the menstrual cycle, and no associated nipple discharge. The patient had no previous history of breast problems and no family history of breast or ovarian carcinoma. She was nulliparous and had used the oral contraceptive pill continuously since the age of 18 years. The patient's general health was otherwise good, and she reported no unusual cough, back pain, or weight loss. Interestingly, she had been treated for a Wilm's tumor of the right kidney at the age of four years and received adjuvant treatment with both radiotherapy and chemotherapy. There was no evidence of any disease recurrence at a recent routine follow-up.