Undifferentiated (anaplastic) carcinoma with osteoclast-like giant cells of the pancreas: a series of 5 cases with clinicopathologic correlation and cytomorphologic characterization

Introduction Undifferentiated carcinoma with osteoclast-like giant cells of the pancreas (UCOGCP) is a rare neoplasm involving the pancreas. Although typically diagnosed initially via endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA), cytomorphologic characterization of the neoplasm has been limited to individual cases in the literature. Materials and methods Five cases were identified in a retrospective review of our institution's records from 2006 to 2015. Cytomorphologic, immunophenotypic, and corresponding clinical features of the neoplasm are examined and described. Results UCOGCP accounted for 0.9% of all new pancreatic neoplastic diagnoses, had a median greatest dimension of 4.3 cm, were variably located within the pancreas, and had variable features by radiologic imaging. Patients were of a median age of 78 years old at diagnosis, and had a median length of survival of 10 months. Smear-based cytomorphology and histomorphology from cell block preparations show atypical/pleomorphic mononuclear carcinomatous and bland osteoclast-like giant cellular populations. The immunophenotype of the mononuclear carcinomatous component was CD68, CD99, CK7 (variably), CKAE1/AE3 (variably), and, rarely, p40-positive. The osteoclast-like giant cells positively expressed CD68 and CD99. Conclusions Initial diagnosis of UCOGCP is frequently made via EUS-FNA of pancreas tumors, with cytomorphologic features on smears and hematoxylin and eosin stained slides prepared from cell block material being characteristic for the diagnosis. Although the cellular constituents have a consistent immunophenotype, the diagnosis can be based on the morphologic features alone. UCOGCP is an important diagnosis as it may have a distinct clinical course from undifferentiated carcinomas of the pancreas lacking osteoclast-like giant cells.