Abstract
Mammary adenocarcinomas showing positive reactivity for estrogen receptor (ER), which were found in two female Western European hedgehogs (Erinaceus europaeus) over 5 years old, were successfully treated with surgical excision, but other malignant tumors occurred subsequently. In case 1 (cribriform carcinoma), the neoplastic tissue was characterized by formation of tubular spaces. In the majority of the tissue, there were large numbers of remaining myoepithelial cells, which were demonstrated distinctly by immunohistochemistry for alpha smooth muscle actin (SMA) and cytokeratin. A forearm tumor, which occurred 9 months after surgery, was diagnosed as myofibroblastic sarcoma, because the neoplastic spindle-shaped cells showed an SMA-positive and desmin-negative immunophenotype. In case 2 (comedo carcinoma), tumor cell nests showed central comedo necrosis, and lacked SMA-positive myoepithelial cells. Approximately 13 months after surgery, the animal died. Necropsy examination revealed that the animal had renal cell carcinoma, which was judged to be of proximal tubule origin on the basis of immunohistochemistry and electron microscopy.
