Neuroendocrine Tumor (Paraganglioma) in an Adult Bovine

are derived from the neuroectodermaltissue, whereas the sustentacular cellsare related to satellite cells of the auto- nomic ganglia. The chief cellscontain neurosecretory gran- ules and may secrete catacholamines. These catacholamines may include serotonin and norepinephrine. The sustentac- ular cells lack granules and catacholamines. In human para- gangliomas, the chief cellscontain neuron-specific enolase, chromogranin, and leu-enkephalin. The sustentacular cellscontain S-100 protein and glial fibrillary acid protein 4 This report presents the histopathologic, immunohistochemical, and ultrastructural evidence of a chemoreceptortumor orig- inating from the heart of a dairy cow. The Wisconsin Central Animal Health Laboratory re- ceived an intact heart and liver specimens from an adult multiparous Holstein dairy cow. This cow had a good ap- petite but steadily lost weight and body condition. At 3-4 weeks postpartum, she had lost approximately 130-180 kg of body mass and ceased milk production. By 6 weeks post- partum, her appetite was still very good, but the weight loss continued, severe ventral edema extended from the cranial cervical to ventral thoracic area, and a terminal diarrhea developed. The heart had a large, firm, multilobulated expansile mass located at the right atrioventricular junction. This mass was approximately 15 x 15 x 10 cm and appeared to incorporate the right coronary artery(Fig. 1). The mass almost obliterated the right atria1 and ventricular lumens and was evenly dis- tributed between the chambers (Fig. 2). The mass further enveloped the right atrioventricular valve, including the chordae tendineaeand papillary muscles. The cut surface was a mottledtan-brown and contained multifocal hemor- rhages. The congested and enlarged liverwas a mottledred- tan and had a reticulated pattern on the cut surface. The representative areas of the tumor and liver were fixed