Fine needle aspiration cytology of acinar cell carcinoma of the pancreas: a report of two cases.

BACKGROUND: Fine needle aspiration in lieu of needle biopsy is widely used for the diagnosis of pancreatic neoplasms. The cytologic features of ductal carcinomas are well characterized, but the appearances of less common pancreatic neoplasms, such as acinar cell carcinoma (ACC), are not well described.

CASES: We present the cytologic, histologic, immunocytochemical and ultrastructural features of two cases of ACC. The tumors occurred in a 36-year-old woman and 43-year-old man. The aspirate from one case contained neoplastic cells with smooth-contoured nuclei containing one or two prominent nucleoli. The aspirated material from the second case was necrotic, with numerous neutrophils and scattered nests of tumor cells similar to those present in the first case. Histologically, both tumors manifested solid and acinar patterns, and each contained some cells with periodic acid-Schiff-positive granules that were resistant to diastase. The neoplasms were immunochemically positive for trypsin and negative for neuroendocrine markers. Ultrastructurally, the aspirate from one case demonstrated apical microvilli, zymogenlike granules and abundant rough endoplasmic reticulum.

CONCLUSION: Uncommon pancreatic neoplasms may be difficult to diagnose due to their cytologic and histologic subtleties. Supplemental studies including immunocytochemistry, cytochemistry and electron microscopy are important in facilitating their identification.