An Extremely Rare Variant of Pancreatic Ductal Adenocarcinoma Masquerading as Chronic Pancreatitis

Abstract Introduction/Objective Primary Pancreatic signet-ring cell carcinoma (PPSRCC) is an extremely rare histologic variant with sparse literature. Herein, we describe a case of PPSRCC in a 75-year-old female with positive family history of pancreatic cancer (47y/o brother). The diagnosis was delayed secondary to diagnostic challenges on initial fine-needle aspiration (FNA). Methods/Case Report Diagnosing PPSRCC on FNA can be extremely difficult. Primary, and metastatic neoplasms to the pancreas may exhibit cytomorphological similarities to signet-ring cells, posing diagnostic challenges. Further, sampling of abundant background inflammatory cells during a biopsy can result in incorrect diagnosis of pancreatitis. Given the strong clinical suspicion based on imaging findings, a second FNA was performed which showed few atypical cells suspicious for carcinoma. Subsequently, the patient underwent neoadjuvant chemotherapy and Whipple resection. The tumor morphology is characterized by infiltrating cells with large mucin vacuoles and peripheric nucleus comprising > 50% of the mass lesion with perineural invasion, in a background of chronic inflammation and pancreatic intraepithelial neoplasia, grade III. A diagnosis of PPSRCC was rendered. Notably, lymph nodes (LN) showed no evidence of metastasis. Results (if a Case Study enter NA) NA. Conclusion Based on limited literature, PPSRCC is considered an aggressive malignancy with low survival rate, because of a high rate of metastasis. However, our case was rather unique given the lack of LN metastasis and the neodjuvant treatment strategy. As of February 2022, <10 cases have been reported with ill-defined characteristics and treatment guidelines.