A case of mixed adenoneuroendocrine carcinoma of the pancreas: Immunohistochemical analysis for histogenesis

Abstract

Rationale: Tumors with multiple histological features, such as adenocarcinomas and neuroendocrine carcinomas, were included as a new category of neuroendocrine carcinomas in the 2010 World Health Organization classification. We recently experienced a rare case of a pancreatic carcinoma with both adenocarcinoma and neuroendocrine carcinoma components, a so-called mixed adenoneuroendocrine carcinoma.

Patient concerns and diagnosis: A 66-year-old man was referred to our hospital with obstructive jaundice. Contrast-enhanced computed tomography images indicated a tumor located at the pancreatic head measuring 3.0 × 2.5 cm in diameter and invading the common bile duct. Cytological examination of the bile juice obtained by endoscopic retrograde cholangiopancreatography revealed adenocarcinoma cells. Pancreaticoduodenectomy was performed safely as radical resection.

Interventions: Microscopically, the resected tumor consisted of tightly intermingled adenocarcinoma and neuroendocrine carcinoma components. On the immunohistochemical examination, p53 was ubiquitously positive in both components, whereas chromogranin A, synaptophysin and neuron-specific enolase, neuroendocrine markers, were limited to the neuroendocrine carcinoma component.

Outcomes: Thus, such features of both adenocarcinoma and neuroendocrine carcinoma observed microscopically and immunohistochemically seemed to indicate a composite tumor.

Lessons: The findings of this case suggest that adenocarcinoma and neuroendocrine carcinoma may be derived from a single cancer stem cell.

Figure 1

Contrast-enhanced computed tomography images showing a tumor in the pancreatic head measuring 3.0 × 2.5 cm in diameter and invading the common bile duct (indicated by a blue arrow). Lymphadenopathy was observed posterior to the pancreatic head (red arrow).

Figure 2

Microscopic and immunohistochemical appearance of the tumor. (A) Primary tumor (hematoxylin and eosin staining, original magnification ×20). The primary lesion was composed of a well-differentiated adenocarcinoma component and a poorly differentiated NEC component, each tightly intermingled. (B) Immunohistochemical staining of the primary lesion for CEA (original magnification ×20). CEA was limited to the well-differentiated adenocarcinoma component of the primary lesion. (C) LN no. 12 exclusively contained the well-differentiated adenocarcinoma component (original magnification ×20). (D) LN no. 13 exclusively contained the poorly differentiated NEC component (original magnification ×20). (E) Immunohistochemical staining of the primary lesion for chromogranin A (original magnification ×20). Chromogranin was limited to the poorly differentiated NEC component of the primary lesion. (F) Immunohistochemical staining of the primary lesion for synaptophysin (original magnification ×20). Synaptophysin was limited to the poorly differentiated NEC component of the primary lesion. (G) Immunohistochemical staining of the primary lesion for NSE (original magnification ×20). NSE was limited to the poorly differentiated NEC component of the primary lesion. (H) Immunohistochemical staining of the primary lesion for p53 (original magnification ×20). p53 was ubiquitously expressed in both the well-differentiated adenocarcinoma and poorly differentiated NEC components of the primary lesion. The well-differentiated adenocarcinoma component can be seen on the right sides and the poorly differentiated NEC component can be seen on the left (E, F, G, and H). CEA = carcinoembryonic antigen, LN = lymph node, NEC = neuroendocrine carcinoma, NSE = neuron-specific enolase.