### Overview - **Rare, aggressive pancreatic malignancies** characterized by spindle-cell or pleomorphic morphology resembling mesenchymal tumors. - Most represent variants of **pancreatic ductal adenocarcinoma (PDAC)** with sarcomatoid differentiation. - Thought to arise through epithelial–mesenchymal transition (EMT). ### Pathology - **Sarcomatoid carcinoma:** Malignant spindle-cell morphology with epithelial differentiation, often demonstrated by cytokeratin expression. - **Carcinosarcoma:** Distinct malignant epithelial and mesenchymal components; considerable overlap exists with sarcomatoid carcinoma. - **Focal sarcomatoid features:** Limited sarcomatoid differentiation within an otherwise conventional carcinoma; does not independently alter TNM stage. - Immunohistochemistry may demonstrate cytokeratin positivity and vimentin expression. Exclude other spindle-cell neoplasms, including GIST. ### Clinical Significance - Generally associated with **aggressive biology and poor prognosis**, although evidence is limited to small retrospective series and case reports. - Prognostic significance of _focal_ sarcomatoid differentiation is poorly established. - No validated sarcomatoid-specific staging system or treatment algorithm. ### Management - **Resectable disease:** Surgical resection when oncologically appropriate. - **Systemic therapy:** Generally follows PDAC paradigms, including FOLFIRINOX-based or gemcitabine-based regimens. - **Surveillance:** Follow standard PDAC postoperative surveillance practices. **Surgical Pearl:** Focal sarcomatoid differentiation on a Whipple specimen is an adverse histologic observation, but does not independently change staging or mandate a different adjuvant regimen. Interpret alongside margins, nodal status, grade, and treatment response.