Case report: Osteolytic metastases from a pheochromocytoma presenting as multiple limb lameness and joint swelling in a dog

Madeleine Swindell¹Timothy A Bolton^2*Cassandra M Powers³Ladislav Novotny^3,4Jack Jarvis¹Masahiro Murakami²

• ¹College of Veterinary Medicine, Purdue University, West Lafayette, Indiana, United States
• ²Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Purdue University, West Lafayette, Indiana, United States
• ³Department of Comparative Pathobiology, College of Veterinary Medicine, Purdue University, West Lafayette, Indiana, United States
• ⁴Department of Veterinary Sciences, Faculty of Agrobiology, Food and Natural Resources, Czech University of Life Sciences Prague, Prague, Prague, Czechia

Clinical signs due to distant bony metastasis from a malignant pheochromocytoma are rare in the dog, with most reported cases manifesting as single limb lameness. This case report describes a 6-year-old male neutered mixed breed dog presenting with multiple limb lameness and joint swelling of 3-weeks' duration. Computed tomography revealed a right adrenal gland mass with extensive intrathoracic, intra-abdominal, and skeletal metastases. Because of the poor prognosis, the dog was humanely euthanized. Post-mortem examination revealed a primary right adrenal gland neoplasm with metastases affecting the contralateral adrenal gland, kidneys, lungs, liver, and bones of the appendicular and axial skeletons. Immunohistochemistry confirmed a metastatic neuroendocrine carcinoma of the right adrenal gland, consistent with a pheochromocytoma. This case is a unique presentation of the polyostotic metastases from a pheochromocytoma, emphasizing the importance of including this tumor in the differential diagnosis of a dog with a clinical presentation identical to polyarthritis.