Morphological and Immunohistochemical Characterization of Spontaneous Mammary Tumours in European Hedgehogs (Erinaceus europaeus)

SummaryMammary tumour samples (11 surgical and five post-mortem) from 16 adult European hedgehogs submitted between 1980 and 2004 were examined. Histologically, the tumours were classified as simple tubulo-papillary carcinomas with local invasive growth. In six cases, tumour cell emboli were present in blood vessels or lymphatic vessels, or both. However, metastasis to regional lymph nodes was found only in one hedgehog. Malignant neoplastic epithelial cells were immunolabelled by antibodies specific for various cytokeratins (CKs), including CK1–8, 10, 13–16, 19 and 20. CK expression did not differ from that in normal mammary gland tissue. CK20 was expressed in the mammary tissue of hedgehogs, in contrast to that of dogs and cats; CK7 immunolabelling, however, which commonly occurs in mammary epithelial cells, was negative. CK20 expression, together with the lack of CK7 as determined by a protein-specific antibody, represented an important difference from the CK profile shown by mammary epithelial cells of other mammalian species, including the dog and cat.