An African American male to female transgender patient treated with estrogen detected a breast lump that was confirmed by her primary care provider. The patient refused mammography and 14 months later she was diagnosed with metastatic breast cancer with spinal cord compression. We used ethnographic interviews and observations to elicit the patient's conceptions of her illness and actions. The patient identified herself as biologically male and socially female; she thought that the former protected her against breast cancer; she had fears that excision would make a breast tumor spread; and she believed injectable estrogens were less likely than oral estrogens to cause cancer. Analysis suggests dissociation between the patient's social and biological identities, fear and fatalism around cancer screening, and legitimization of injectable hormones. This case emphasizes the importance of eliciting and interpreting a patient's conceptions of health and illness when discordant understandings develop between patient and physician.