Combined hepatocellular-cholangiocarcinoma in a Yellow-headed Amazon (Amazona oratrix)

Abstract

A 9-year-old male Yellow-headed Amazon (Amazona oratrix) with a history of anorexia and vomiting died of a liver tumor. The tumor consisted of neoplastic cells with hepatocellular and cholangiocellular differentiations and their intermingled areas. Neoplastic hepatocytes showed islands or trabecular growth with vacuolated eosinophilic cytoplasm. Cells showing biliary differentiation formed ducts or tubules lined by cytokeratin AE1/AE3-positive epithelia, accompanied by desmoplasia consisting of myofibroblasts reacting to α-smooth muscle actin and desmin. The tumor was diagnosed as a combined hepatocellular-cholangiocarcinoma, which is very rare in the avian.

Fig. 1.

Gross finding. The liver shows pale brown color; and has irregular surface and nodular masses of 1-3 cm in diameter (asterisks). Inset shows the cut surface after formalin fixation. Bar=1 cm.

Fig. 2.

Area consisting of islands of cells with hepatocellular differentiation with vacuolated eosinophilic cytoplasm (arrows) and areas with trabecular growth (arrowhead). HE stain. Bar=50 µm. Inset shows cytoplasmic vacuoles stained red by oil red O stain. Bar=20 µm.

Fig. 3.

Biliary differentiation area consisting of ducts or tubules lined by monolayered columnar epithelial cells (arrows) and abundant collagen (desmoplastic stroma). HE stain. Bar=20 µm. An arrowhead indicates neoplastic hepatocytes.

Fig. 4.

Intermediate differentiation area composed of an admixture of hepatocellular (arrowheads) and cholangiocellular components (asterisks). HE stain. Bar=50 µm.

Fig. 5.

Desmoplastic stroma in the cholangiocellular differentiation area; the stroma is stained blue by the azan-Mallory stain among ducts or tubules formed by neoplastic cholangiocytes. Azan-Mallory stain. Bar=50 µm.

Fig. 6.

The desmoplastic stroma in the cholangiocellular differentiation area consisting of α-smooth muscle actin-positive myofibroblasts (arrows). Immunohistochemistry, counterstained with hematoxylin. Bar=20 µm.

Fig. 7.

The desmoplastic stroma in the cholangiocellular differentiation area consisting of desmin-positive myofibroblasts (arrows). Immunohistochemistry, counterstained with hematoxylin. Bar=20 µm.

Fig. 8.

Cells forming ducts or tubules (arrows) in the cholangiocellular differentiation area react to cytokeratin AE1/AE3. Some AE1/AE3-positive cells are present without forming cavity (asterisks) or as a single cell (arrowhead). Immunohistochemistry, counterstained with hematoxylin. Bar=20 µm.

Fig. 9.

Neoplastic cells showing the proliferating activity, demonstrated by the PCNA immunolabeling in the cholangiocellular differentiation area (short arrows) and in hepatocellular differentiation area (arrowheads). Some interstitial cells (long arrows) show a PCNA positivity. Immunohistochemistry, counterstained with hematoxylin. Bar=50 µm.

Fig. 10.

PCNA-positive, proliferating biliary epithelial cells react to AE1/AE3 (arrows). Double immunolabeling for AE1/AE3 (red in cytoplasm) and PCNA (brown in nuclei). Cells reacting to PCNA, but negative to AE1/AE3 are neoplastic hepatocytes (arrowheads). Bar=20 µm.