also present an overview of our patient's proposed treatment in the context of the 16 other reported lelc cases. CASE PRESENTATIONA 55-year-old postmenopausal woman originally from Ghana presented with a 4-week history of left breast tenderness and an upper outer quadrant mobile breast mass. She had been mammographically screened, with the most recent mammogram (performed 1 year before her presentation) having demonstrated no abnormalities. Her past medical history was unremarkable, with a surgical history of Cesarean section, tubal ligation, and hernia repair. She was gravida 2, para 2, with menopause having occurred at age 53. On systems review, she denied fevers, chills, or night sweats. No weight loss was reported, and she was asymptomatic but for left breast tenderness.Physical examination revealed no cervical or axillary adenopathy, but was significant for a diffusely swollen left breast with a discrete, mobile 4-cm mass. The exam was otherwise noncontributory.Mammography revealed a 3-to 4-cm upper outer quadrant density with spot compression views showing lobulated margins. No evidence of calcifications was noted. Breast ultrasonography showed a 4.3×3.5×2.6-cm lobulated, poorly marginated, hypoechoic solid mass. Computed tomography of the thorax, abdomen, and pelvis showed no evidence of distant metastases and the presence of an 8-cm left breast mass with a uniform low-density component (Figure 1).Fine-needle aspirate yielded a cellular specimen noteworthy for single and groups of abnormal elongated cells with visible nucleoli presenting together with lymphocytes and plasma cells. A bone marrow biopsy revealed normocellular marrow with no evidence of lymphoproliferative disorder.An excisional biopsy was followed by 3 successive pathology reviews. The initial consultant ABSTRACTWe present a patient with lymphoepithelioma-like carcinoma (lelc) of the breast whose diagnosis is illustrative of the pathology nuances that must be taken into account to successfully reach correct identification of the disease. We also present an overview of our patient's proposed treatment in the context of 16 other reported lelc cases. Although lelc cases are rare, a sufficient number have been reported to discern the natural history of this pathologic entity and to undertake a review of those cases and of the application of oncologic first principles in their management. Given the potential for locoregional spread and distant metastases in lelc, adjuvant therapy has a role in the treatment of this entity.

Undifferentiated carcinoma of the endometrium is a rare neoplasm, which, when involving the cervix, raises a question about its origin. Diffuse p16 positivity of uterine cancers is usually interpreted as a surrogate marker for high-risk human papilloma virus and favors cervical origin. In this study, we investigated the expression of cytokeratin 7 (CK7), monoclonal carcinoembryonic antigen (mCEA), estrogen receptor (ER), vimentin, and p16 in 28 cases of undifferentiated endometrial carcinoma, 20 high-grade endometrioid adenocarcinomas, and 50 cervical adenocarcinomas. Staining was considered positive when it was cytoplasmic for CK7, mCEA, and vimentin, nuclear for ER, and both nuclear and cytoplasmic for p16. Percentages of cells staining were recorded as follows: negative (0%-5%), 1+ (6%-25%), 2+ (26%-50%), 3+ (51%-75%), and 4+ (>75%). P16 was considered positive if it stained more than 75% of the tumor cells. Diffuse/strongly positive staining for p16 was seen in 40/50 (80%) cases of cervical adenocarcinoma and 14/28 (50%) cases of undifferentiated endometrial carcinoma. In high-grade endometrioid adenocarcinoma, staining was mainly patchy. CK7, mCEA, ER, progesterone receptor, and vimentin staining in undifferentiated endometrial carcinoma was as follows: 10/28 (36%), 4/28 (14%), 21/28 (75%), 23/28 (82%), and 26/28 (93%), respectively; for high-grade endometrioid carcinoma: 20/20 (100%), 1/20 (5%), 17/20 (85%), 18/20 (90%), and 19/20 (95%); for endocervical adenocarcinoma: 50/50 (100%), 45/50 (90%), 9/50 (18%), 8/50 (16%), and 6/50 (12%), respectively. Our data indicate that p16 may play a role in the tumorigenesis of a subset of undifferentiated endometrial carcinoma. In the setting of p16 positivity, undifferentiated endometrial carcinomas are more likely to be ER, progesterone receptor, and vimentin positive and mCEA negative when compared with endocervical adenocarcinomas. Distinction between undifferentiated endometrial carcinoma and endocervical adenocarcinoma, both of which can share diffuse p16 expression, should rely on detection of human papilloma virus in the latter.