Extended Survival with Pancreatic Carcinosarcoma: A Case Report and Literature Review

Abstract

Pancreatic carcinosarcoma is a rare and aggressive malignancy that can mimic pancreatic adenocarcinomas in presentation but often has different disease biology and different responses to conventional treatment for pancreatic adenocarcinoma. Case reports have documented a 5-year overall survival of approximately 13% only if the disease is caught at an earlier stage and is amenable to multi-modality treatment, including surgery, chemotherapy, and radiation. In the advanced stage, treatments do not often provide benefit, and patients may decline rapidly. There are currently no studies demonstrating survival benefits with chemotherapy in patients with metastatic carcinosarcoma, owing to both the rarity and the often late diagnosis of this aggressive entity. We present a case of a 71-year-old male patient diagnosed with metastatic pancreatic carcinosarcoma who received four lines of palliative-intent treatment: gemcitabine and nab-paclitaxel, modified FOLFIRINOX, GTX, and doxorubicin. With careful selection of chemotherapeutic regimen as well as his ability to tolerate four lines of treatment, this resulted in an unprecedented 26-month survival. We also reviewed the literature on the histopathology, diagnosis, and treatment of this rare entity.

Keywords: chemotherapy; extended survival; multi-disciplinary; pancreatic carcinosarcoma; rare tumors.

Figure 1

IHC staining of the EUS-guided biopsy of the primary pancreatic head mass. (A) The tumor shows 2 distinct components, partially intermingling: the mesenchymal component (blue stars on the left side of the image) and the epithelial component, composed of moderately differentiated ductal adenocarcinoma (on the right side). The ductal adenocarcinoma is composed of angulated glands lined by low cuboidal epithelium. Hematoxylin and eosin, 20×. (B) The epithelial component (on the right side) shows strong keratin cytoplasmic staining of the tumor cells, while completely negative in the mesenchymal component (blue star). CK7 immunohistochemical stain, 20×. (C) The mesenchymal component is composed almost entirely of large, epithelioid cells, some with pleomorphic nuclei, prominent nucleoli, and numerous atypical mitotic figures. Focally, myxoid stroma is noted (left side of the image). Hematoxylin and eosin, 60×. (D) All the tumor cells in the mesenchymal component are strongly positive for vimentin (blue star), while the epithelial component is negative (arrows). Vimentin immunohistochemical stain, 60×.

Figure 2

Proposed theories for the pathogenesis of carcinosarcoma. (Left) Collision Tumor Theory: Two independent neoplastic clones arise in proximity and ultimately collide, forming a composite tumor mass. This model is supported when distinct histological or molecular profiles are observed in adjacent but genetically unrelated tumor components [11,17]. (Center) Combination Theory: A single progenitor cell gives rise to divergent tumor phenotypes through early lineage bifurcation. This theory is supported by shared driver mutations or clonal markers despite differing morphologies [12,13,18]. (Right) Epithelial-to-Mesenchymal Transition (EMT) Theory: Epithelial tumor cells undergo EMT, a biological process that enables them to acquire mesenchymal features associated with invasiveness, migration, and therapeutic resistance. Evidence for EMT includes morphological changes and differential expression of markers such as decreased E-cadherin and increased vimentin [19]. Understanding which of these mechanisms predominates in a given tumor can inform diagnostic interpretation and therapeutic decision-making.