Case ReviewsUndifferentiated Carcinoma of the Pancreas With/Without Osteoclast-Like Giant CellsTanaka, Mariko MD*; Fukayama, Masashi MD, PhD*; Fukushima, Noriyoshi MD, PhD†Author Information From the *Department of Pathology, Graduate School of Medicine, The University of Tokyo, Tokyo; and †Department of Pathology, Jichi Medical University, Tochigi, Japan. Reprints: Noriyoshi Fukushima, MD, PhD, Department of Pathology, Jichi Medical University, 3311-1 Yakushiji, Shimotsuke-shi, Tochigi 329-0498, Japan. E-mail: [email protected]. Pathology Case Reviews: November-December 2010 - Volume 15 - Issue 6 - p 210-214 doi: 10.1097/PCR.0b013e3181ffb8ac Buy Metrics Abstract Undifferentiated carcinoma of the pancreas is a rare malignant epithelial neoplasm with a significant component showing no particular differentiation such as keratinization, glandular structure, or mucin production. Clinical recognition of this neoplasm is important because of its poor prognosis with a mean survival of 5 months. The primary diagnostic challenge for surgical pathologists is to distinguish undifferentiated carcinoma from poorly differentiated epithelial, mesenchymal, germ cell, hematopoietic, and other neoplasms. In addition to the morphological characteristics, immunohistochemical analyses are useful for differential diagnosis. In this article, we present a case of undifferentiated carcinoma of the pancreas, followed by a discussion focused on the differential diagnosis of undifferentiated carcinoma, as well as histomorphologic/cytomorphologic, ultrastructural, and immunophenotypic findings helpful for the diagnosis. © 2010 Lippincott Williams & Wilkins, Inc.