Concurrent chronic lymphocytic leukemia and primary hyperparathyroidism in a mule

Area of Science:

• Veterinary Medicine
• Equine Internal Medicine
• Hematology
• Oncology

Background:

• Chronic weight loss and decreased appetite are common presenting complaints in aged equids.
• Hypercalcemia and lymphocytosis can indicate various underlying pathologies.

Observation:

• A 26-year-old mule gelding presented with a 7-month history of weight loss and intermittent hypophagia.
• Laboratory findings included severe hypercalcemia, hypophosphatemia, elevated parathyroid hormone, and marked lymphocytosis.

Findings:

• Flow cytometry and PCR for antigen receptor rearrangement (PARR) results were indicative of a B cell lymphoproliferative disorder, consistent with chronic lymphocytic leukemia (CLL).
• A sestimibi scan to localize parathyroid tissue was nondiagnostic.

Implications:

• This case highlights the concurrent presentation of hypercalcemia and chronic lymphocytic leukemia (CLL) in an aged equid, a combination not previously well-described.
• The co-occurrence of these conditions complicates the determination of the primary cause for weight loss and hypercalcemia in this patient.
• Further investigation into the interplay between lymphoproliferative disorders and metabolic derangements like hypercalcemia in equids is warranted.