The biopsy specimens revealed that there was an infiltrate in the lower dermis, with tumor cells forming strands and cords and dissecting collagen bundles. The cells were forming glandularlike structures. The epidermis was unremarkable. Immunohistochemical analysis showed that the tumor cells were positive for cytokeratin 7 and gross cystic disease fluid protein and negative for prostate-specific antigen, S100 protein, and cytokeratin 20. In this case, the tumor cells were also highlighted by cytokeratin AE1/AE3 and CAM 5.2. This immunohistochemical profile was consistent with breast tissue as being the primary site of the malignancy. Immunostains for the estrogen and progesterone receptors revealed a positivity of less than 10%. A computed tomograpic scan revealed an infiltrating tumor in the breast, with gynecomastia but no pulmonary invasion. A computed tomographic scan of the abdomen and pelvis revealed no abnormalities. The patient was referred to oncology for treatment. He completed radiation therapy and was to begin a regimen of systemic chemotherapy.
Large Plaque on the Chest Extending to the Back—Diagnosis. Arch Dermatol. 2003;139(11):1497–1502. doi:10.1001/archderm.139.11.1497-a
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