Metaplastic breast carcinoma is very rare, and metaplastic carcinoma with chondroid differentiation is even rarer. Here, we report a case of metaplastic carcinoma with extensive chondroid differentiation mimicking chondrosarcoma that was challenging to diagnose. The tumor was characterized by an abundant chondromyxoid matrix. The definitive area of classic invasive ductal carcinoma was minimal. The peripheral portion of the tumor showed increased cellularity with pleomorphism and definitive invasive growth. Tumor cells in the chondrosarcomatous areas were diffusely immunoreactive for S-100 protein, patchy positive for cytokeratin, but negative for epithelial membrane antigen (EMA). Tumor cells in carcinomatous areas were diffusely positive for cytokeratin, S-100 protein, and patchy positive for EMA. In both areas, tumor cells were negative for smooth muscle actin (SMA) and CD34, while oncoprotein p53 was overexpressed. When pathologists encounter breast tumors with chondroid differentiation, careful sampling and immunohistochemistry for cytokeratin and SMA are most helpful to differentiate metaplastic carcinoma from malignant phyllodes tumor and malignant adenomyoepithelioma.
S100 Proteins/chemistry ; Neoplasm Metastasis ; Muscle, Smooth/pathology ; Middle Aged ; Metaplasia ; Keratins/metabolism ; Immunohistochemistry ; Humans ; Female ; Cell Differentiation ; Carcinoma/*complications/metabolism/pathology ; CA-15-3 Antigen/metabolism ; Breast Neoplasms/complications/metabolism/*pathology ; Antigens, CD34/biosynthesis ; Actins/metabolism

The term "chordoid meningioma" means meningioma, which is pathologically similar to chordoma, and previously reported that rarely associated with microcytic anemia and/or dysgammaglobulinemia especially in pediatric population. We present a case of this rare variant, which comprises less than 0.5% of all meningiomas. A 33-yr-old man visited our hospital, complaining visual field defect worsening over 7 yr. Neurological examination showed left homonymous hemianopsia. The brain magnetic resonance imaging revealed well enhancing right temporo-occipital mass with cystic portion. Histopathologic findings of resected tumor were compatible with chordoid meningioma which included trabeculae of eosinophilic, vacuolated cells in a myxoid matrix with prominent lymphoplasmacellular infiltration. The neoplastic cells were positive for vimentin and epithelial membrane antigen and negative for glial fibrillary acidic protein and cytokeratin. This is an adult case of chordoid meningioma without anemia or dysgammaglobulinemia.
Adult ; Antigens, CD20/biosynthesis ; Antigens, CD3/biosynthesis ; B-Lymphocytes/pathology ; Brain/pathology ; Brain Neoplasms/*diagnosis/*pathology ; CA-15-3 Antigen/biosynthesis ; Chordoma/*diagnosis/*pathology ; Human ; Magnetic Resonance Imaging ; Male ; Meningeal Neoplasms/*diagnosis ; Meningioma/*diagnosis ; T-Lymphocytes/pathology ; Vimentin/biosynthesis ; Visual Fields