Clinicopathologic and electron microscopic study of cutaneous neuroendocrine (Merkel cell) carcinoma in a cat with comparisons to human and canine tumors

Malignant neuroendocrine carcinoma of the skin (Merkel cell tumor) was diag nosed in an 18-year-old spayed female Maine Coon Cat. The diagnosis was mad e on the basis of morphologic and electron microscopic findings. The cat wa s euthanatized 321 days after surgical excision of the tumor. The tumor's m alignancy contrasted with the benign nature of Merkel cell tumors reported in dogs and was consistent with the malignancy of Merkel cell tumors report ed in humans.