Fetus in Fetu in a Harbor Seal ( Phoca vitulina richardi): Histopathologic, Genetic, and Toxicologic Analysis

• Published in: Veterinary Pathology
• Main Authors: Buckles, E. L., Gulland, F. M. D., Aldridge, B. M., Gelatt, T. S., Ross, P. S., Haulena, M., Lowenstine, L. J.
• Format: Article in Journal/Newspaper
• Language: English
• Published: SAGE Publications 2006
• Subjects: harbor seal; Phoca vitulina
• Online Access: http://dx.doi.org/10.1354/vp.43-4-541; https://journals.sagepub.com/doi/pdf/10.1354/vp.43-4-541; https://journals.sagepub.com/doi/full-xml/10.1354/vp.43-4-541

A young harbor seal (Phoca vitulina richardi), stranded on the coast of California, was found to have a 20-cm-diameter cranial cervical mass. Surgical excision revealed the subcutaneous mass to be covered in haired skin with multiple glabrous areas and structures resembling a jaw with tooth buds, eyelids, and a tail. The mass deformed the host pup's skull. Histologic examination revealed a complete vertebra in the tail, teeth in the jaw, and areas resembling tongue and larynx. Class 1 MHC sequences amplified by polymerase chain reaction from the mass and the host twin were identical. The mass was diagnosed as a fetus in fetu, a rare congenital anomaly in which 1 conjoined twin is completely enclosed in the body of the other twin. The host pup died, and no additional defects were found; however, blubber levels of persistent organic pollutants were high. The cause of the congenital anomaly in this pup is uncertain.