Primary sarcoma of the breast is extremely rare and it is a diagnosis of exclusion, notably metaplastic carcinomas and malig-nant phyllodes tumors. We present a case of 53-year old Korean female with undifferentiated pleomorphic sarcoma with CD10 expression. It was a high grade tumor composed of spindle cells, and immunohistochemical analysis revealed negati- vity for cytokeratins and CD34, but focal positivity for actin, diffuse positivity for CD10 and vimentin. These results led to the diagnosis of undifferentiated pleomorphic sarcoma. This case represents a rare variant of primary breast sarcoma which imposes a diagnostic difficulty, and highlights the importance of CD10 expression.

Mixed adenoneuroendocrine carcinoma (MANEC) of the biliary tract is rare. Here, the authors report a case of MANEC of the gallbladder, in which neuroendocrine carcinoma (NEC) exhibited collision and sharp separation from a moderately differentiated adenocarcinoma; these two tumor components made up of more than 30% of the entire tumor, respectively. The tumor metastasized to liver and one lymph node, and the hepatic metastatic component was from an neuroendocrine tumor (NET), while the lymphovascular invasion and lymph node metastasis was attributed to adenocarcinoma. Ki-67 im-munostaining (>50%) and numerous mitotic counts showed the NET exhibited high proliferative activity. Because the neuroendocrine component in biliary MANEC defines prognosis, its identification is of considerable importance.

Calcifying fibrous tumor (CFT) is a rare benign soft tissue mass consisted of abundant densely hyalinized collagen with calcifications and patchy infiltration of lymphocytes and plasma cells. The etiology and pathogenesis of this entity are unknown. Recently we experienced a case of CFT of the peritoneum in 37-year-old man. Complete removal of this lesion was performed.

Primary adenocarcinoma is a rare neoplasm of the urinary bladder, constituting approximately 2.5% of all primary bladder malignancies. Signet ring cell variant is even rarer, constituting approximately 0.5% to 2.0% of all primary carcinoma of the urinary bladder. However, glandular differentiation in the urinary bladder is relatively more common than primary adenocarcinoma of the urinary bladder. Therefore, diagnosis of primary adenocarcinoma of the urinary bladder can be very challenging, but of significant clinical importance. We report on a case of adenocarcinoma with mucinous and signet ring cell differentiation in the bladder dome in a 49-year-old female.