The good news is this is only a hypothetical case. The bad news is this a hard one. The outpatient medical record says the Nature of Illness. The Nature of Illness is breast cancer. Patient is here for MRI of left breast. Patient had a biopsy which was apparently malignant according to the MRI report. She is to have another mammogram in six months for stability. I am looking at neoplasm, primary, malignant for the codes. Code 174.9 appears for breast cancer, unspecified. Code 174.8 also seems like it could be relevant especially the part "malignant neoplasm of contiguous or overlapping sites of breast whose point of origin cannot be determined". What do you think? Thanks for your help with this. I am confused.