A Rare Pancreatic Tumor with Adenomatoid Tumor-like Findings

Abstract

A 74-year-old woman was referred to our hospital for the evaluation of slightly elevated tumor marker levels. Computed tomography revealed a well-demarcated tumor, approximately 15 mm in diameter, in the pancreatic tail. Endoscopic ultrasound-guided fine-needle aspiration findings suggested poorly differentiated cancer. The tumor was surgically resected, but postoperative pathologic confirmation was not possible. After one year without treatment and no recurrence, an evaluation by a specialized facility was requested for a definitive diagnosis. Adenomatoid tumor was deemed most likely based on the histopathology and immunostaining findings; however, a definitive diagnosis was difficult because of atypical findings. The patient was recurrence-free for 36 months at the last follow-up.

Keywords: adenomatoid; diagnosis; pancreas; poorly differentiated.

Figure 1.

Abdominal dynamic contrast-enhanced computed tomography image showing a tumor, 15 mm in diameter, with a relatively clear boundary in the pancreatic tail (arrow). The tumor has a cyst-like morphology, which is atypical for normal pancreatic cancer. The tumor exhibits a slow contrast effect but with a poor blood flow.

Figure 2.

Abdominal magnetic resonance image showing a hypointense signal at the edge and a hyperintense signal at the center on T2-weighted images (arrow). The mass has a fibrous component at the margin, and the center appears to be necrotic. The mass exhibits mild diffusion restriction and does not exhibit hypercellularity.

Figure 3.

Endoscopic ultrasound imaging showing a well-demarcated hypoechoic mass, 14 mm×16 mm in dimensions, in the pancreatic tail.

Figure 4.

Pathological findings of the specimen collected with endoscopic ultrasound-guided fine-needle aspiration. Hematoxylin and Eosin staining showing atypical cells with a high nucleus/cytoplasm ratio, chromatin-rich macronuclei, and acidophilic vesicles that are mixed with blood clots in the interstitium with exfoliation and vitrification. (a) ×200. (b) ×400.

Figure 5.

Macroscopic findings of the resected specimen, approximately 15 mm in diameter, in the pancreatic tail. (a) Pancreatic body and tail, (b) tumor split plane (arrow).

Figure 6.

Histopathologic and immunohistochemical findings. Atypical cells with different-sized nuclei, vacuolar-like structure, and proliferation with epithelial-like intercellular connections. (a) Hematoxylin and Eosin (H&E) staining, ×100. (b) H&E staining, ×400. c) Immunostaining for cytokeratin AE1/AE3 showing positivity, ×400. (d) Immunostaining for D2-40 showing positivity, ×400. (e) Immunostaining for calretinin showing limited positivity, ×400. (f) Note that there is no loss of methylthioadenosine phosphorylase, ×400.