Pancreatic mixed acinar‐neuroendocrine carcinoma, a unique diagnostic challenge on FNA cytology: A small series of two cases with literature review

Abstract

Mixed acinar‐neuroendocrine carcinoma (MANEC) of the pancreas is a rare tumor. We present two cases of MANEC diagnosed on endoscopic ultrasound (EUS) guided fine‐needle aspiration (FNA). The first patient is a 33‐year‐old male who had a 3.6 cm mass in the uncinate process and liver metastasis. The second patient is a 66‐year‐old male with a 10 cm mass in the pancreatic tail. The FNA smears from both cases were hypercellular with neoplastic cells in loosely cohesive clusters and many naked nuclei. In both cases, the tumor cells were positive for CKAE1/3, synaptophysin, chromogranin, and trypsin by immunohistochemistry. Final diagnoses of MANEC were rendered based on cytological features and immunohistochemical profiles. To date, 44 cases of MANEC have been reported in the English literature, only three of which were diagnosed on cytopathology specimens before surgical resection. Our report adds two more cases diagnosed on cytopathology alone. Herein, we discuss the various cytomorphologic and clinical features of MANEC and present a brief review of the literature. Diagn. Cytopathol.

The cytologic and immunohistochemical findings of pancreatic mixed acinar‐endocrine carcinoma

“…Most patients presented with weight loss, nausea, and abdominal pain. Three patients did present with liver metastases at the time of diagnosis, which is consistent with what has been noted previously 17 …”

“…MAECs, by definition, express acinar antigens, for example, trypsin and chymotrypsin, with neuroendocrine antigens. Individual cells can however demonstrate dual expression of both acinar and neuroendocrine makers 15,17 . Our case review supports the use of a small immunohistochemical panel when a MAEC is suspected.…”

“…There was also discrepancy between the chromogranin performed on the surgical specimen and the FNA specimen, suggesting that use of multiple neuroendocrine markers is necessary to accurately identify neuroendocrine features. The Ki67 index in the literature has been reported to be between 7%‐50%, with more cases in the 30%‐50% range 13,15,17,19 . Our cases demonstrated Ki67 indices between 10% and 48%, with the majority of cases between 20% and 40%.…”

Primary signet ring cell carcinoma of the pancreas: Cytopathology review of a rare entity

“…Mixed acinar and neuroendocrine carcinoma (MANEC) is a rare entity that has been described in the pancreas . The diagnosis of MANEC is made when acinar and neuroendocrine components exceed 25% to 30% of the tumor, each .…”

“…Mixed acinar and neuroendocrine carcinoma (MANEC) is a rare entity that has been described in the pancreas . The diagnosis of MANEC is made when acinar and neuroendocrine components exceed 25% to 30% of the tumor, each . MANEC with signet ring cells is an extremely rare diagnosis that has been reported in the ampulla and pancreas .…”