Osteochondromatosis in a Rhesus macaque (Macaca mulatta)

Area of Science:

• Veterinary Pathology
• Primate Medicine
• Skeletal Biology

Background:

• Osteochondromas are benign cartilage-capped bone tumors that typically occur near growth plates.
• Rhesus macaques (Macaca mulatta) are valuable models in biomedical research, and understanding spontaneous conditions is crucial.

Observation:

• A 5-year-old male rhesus macaque presented with multiple radiopaque masses on the femur.
• Radiographs revealed exophytic masses with mild bony reaction on the proximal tibia.
• Histological examination of biopsy tissue showed woven and lamellar bone with granulation tissue.

Findings:

• Necropsy confirmed cartilage-capped lesions near the distal femur and midshaft of the femur and tibia.
• Histology revealed chondro-osseous exophytic growths consistent with multiple osteochondromas.
• The lesions were well-integrated with the host bone, arising near the growth plate.

Implications:

• This case highlights the importance of recognizing spontaneous skeletal abnormalities in non-human primates.
• Accurate diagnosis of osteochondromas in macaques aids in research study design and animal welfare.
• Understanding the presentation and histology of these lesions contributes to comparative pathology knowledge.