A current knowledge of the undifferentiated carcinoma of the pancreas with osteoclast-like giant cells: a narrative review.

Background and Objective: Undifferentiated carcinoma of the pancreas with osteoclast-like giant cells (UCOGC) is a rare variant of malignant pancreatic tumor. There is still no standardized treatment for this uncommon subtype, as surgical resection with lymphadenectomy is the only potentially curative treatment so far. In this paper, we describe the current knowledge of this very rare specific subtype of pancreatic cancer (PC) as a narrative review. Methods: For this review, we did not specify the time range of studies referred to due to limited data availability. Our inclusion criteria comprised previous studies, which specifically focused on the rare UCOGC subtype of PC as a confirmed histopathology, either pure or present together with other subtypes. We disregarded the studies involving any other PC subtype but not UCOGC, including undifferentiated and anaplastic carcinomas without osteoclast-like giant cell components. Key Content and Findings: The limited available data precludes a definitive assessment of the efficacy of both neoadjuvant and adjuvant chemotherapy in the treatment of UCOGC. Monoclonal antibody pembrolizumab has been proven to be effective in metastatic cases. Multiple cases demonstrate a better overall survival rate for patients with UCOGC only versus those having UCOGC as a component with a pancreatic ductal adenocarcinoma (PDAC) histopathological subtype. The same conclusion can be also drawn comparing the survival rate of patients having pure UCOGC versus UCOGC with associated PDAC. Programmed cell death ligand-1 expression has been shown to be an important determinant, which shortens the survival period of patients diagnosed with UCOGC. Conclusions: The rarity of UCOGC limits data for clinical courses and treatment plans. We need more data to better understand the relationship between pathogenic mutations, histological subtypes, and prognosis in PC, including UCOGC. Understanding UCOGC's molecular, clinical, radiological, and pathological characteristics can lead to earlier, more accurate diagnoses and better management.