Hypercalcemia and high serum parathyroid hormone-related protein concentration in a horse with multiple myeloma.
A 13-year-old gelding was examined because of weight loss, hyperglobulinemia, and hypercalcemia. Possible causes of hypercalcemia that were considered included renal failure, primary hyperparathyroidism, vitamin D toxicosis, and malignancy. There was no history of vitamin D ingestion, and serum creatinine and parathyroid hormone concentrations were normal, making renal failure and primary hyperparathyroidism unlikely. The hypercalcemia was suspected to be a result of malignancy, but thorough testing did not reveal any neoplastic disease. Eight months later, serum parathyroid hormone-related protein (PTHrP) concentration was high, supporting the suggestion that hypercalcemia was a result of malignancy. In addition, radial immunodiffusion confirmed a selective 300-fold increase in serum IgA concentration. The horse was euthanatized, and postmortem examination revealed neoplastic infiltrates in the kidneys, lymph nodes, liver, and bone marrow. Neoplastic cells had morphologic characteristics of plasma cells, and immunohistochemical staining confirmed that neoplastic cells were expressing PTHrP and IgA. The final diagnosis was multiple myeloma with expression of IgA paraprotein.
Department of Large Animal Medicine, College of Veterinary Medicine, University of Georgia, Athens, GA 30628, USA.
Michelle Henry
MH
Barton
Prachi
P
Sharma
Bruce E
BE
LeRoy
Elizabeth W
EW
Howerth
D000818:Animals; D003937:Diagnosis, Differential; D017809:Fatal Outcome; D006734:Horse Diseases / Q000097:blood / Q000175:diagnosis* / Q000209:etiology; D006736:Horses; D006934:Hypercalcemia / Q000209:etiology / Q000662:veterinary*; D007150:Immunohistochemistry / Q000662:veterinary; D008297:Male; D009101:Multiple Myeloma / Q000097:blood / Q000150:complications / Q000175:diagnosis / Q000662:veterinary*; D010281:Parathyroid Hormone / Q000097:blood; D044162:Parathyroid Hormone-Related Protein / Q000097:blood*
D010281:Parathyroid Hormone; D044162:Parathyroid Hormone-Related Protein