Pleomorphic rhabdomyosarcoma with pulmonary metastasis in a stranded Steller (northern) sea lion (Eumetopias jubatus).

Abstract

A Steller (northern) sea lion (SSL), stranded in northern California in July 2000 had an anaplastic pleomorphic rhabdomyosarcoma in the latissimus dorsi muscle, with pulmonary metastasis. Diagnosis was based on light and electron microscopy and immunohistochemistry. Death was attributed to multiple parasitic and bacterial lesions. The SSL is of special concern because, for unknown reasons, the global population has declined by 50% over the last decade. Published post-mortem data, however, are scarce. This case report highlights several disease conditions that affect this species and is the first report of a malignant neoplasm in a free-ranging SSL.