A Case Report of Carcinoma of Mammary Gland with Systemic Metastases in a Captive California Sea Lion (Zalophus californianus)

Abstract

Invasive carcinoma of the mammary gland with systemic metastases was found in a captive nulliparous female California sea lion, over 17 years old. Numerous yellowish white masses of various sizes were discovered in the mammary region and many organs. Microscopically, all the masses consisted of epithelial tumor cells that were irregular in size and shape. Epithelial tumor cells had often invaded adjacent tissues and vessels, especially lymphatics. The tumor cells were arranged mainly in tubular to papillary formations with some solid sheets in the mammary region, whereas principally solid formations were found in the metastatic regions. We diagnosed this as a case of simple tubulopapillary to solid carcinoma of mammary gland with systemic metastases.