Osteosarcoma masked by osteomyelitis and cellulitis in a dog

Summary

Case description: This clinical report describes a 10-year-old female spayed German Shepherd dog cross that was presented with cellulitis of the left proximal forelimb and osteomyelitis of the left proximal humerus, and was ultimately diagnosed with metastatic osteosarcoma.

Clinical findings: The diagnosis of cellulitis and osteomyelitis was made using ultra-sound, radiography, cytology and histopathology, all of which were consistent with cellulitis and osteomyelitis. Cultures were negative.

Treatment: The patient was treated using two surgical debridements and long-term broad-spectrum antibiotic drugs. Despite surgical and medical treatment, the dog’s condition progressed. A lytic lesion of the left proximal humerus was identified radiographically.

Outcome: One hundred forty-one days after initial presentation, the dog was presented with a non-weight bearing lameness of the left forelimb. An amputation was scheduled. Preoperative computed tomography scan of the thorax revealed gross metastatic disease to the lungs. The patient was euthanatized and a post-mortem examination revealed osteosarcoma of the left proximal humerus with widespread metastasis.

Clinical relevance: To our knowledge, this case is the first reported case of osteomyelitis masking osteosarcoma in a dog. It serves as a reminder to maintain a high index of suspicion when managing cases with a signalment, history and radiographic lesion that are consistent with a primary bone tumour.

Keywords

Osteosarcoma - osteomyelitis - bone cancer

• References

• 1 Durbin M, Lor Randall R, James M. et al. Ewing’s sarcoma masquerading as osteomyelitis. Clin Orthop Relat Res 1998; 357: 176-185
• 2 Lyall HA, Constant CR, Wraight EP. Ewing’s sarcoma in distal tibial metaphysis mimicking osteomyelitis. Clin Radiol 1993; 48: 140-142
• 3 Jordanov I M, Block JJ, Gonzalez AL. et al. Transarticular spread of Ewing sarcoma mimicking septic arthritis. Pediatr Radiol 2009; 39: 381-384
• 4 Willis RB, Rozencwaig R. Pediatric osteomyelitis masquerading as skeletal neoplasia. Orthop Clin North Am 1996; 27: 625-634
• 5 Seybold U, Talati NJ, Kizilbash Q. et al. Hematogenous osteomyelitis mimicking osteosarcoma due to a community associated methicillin-resistant staphylococcus aureus. Infection 2007; 35: 190-193
• 6 McGuinness B, Wilson N, Doyle AJ. The “penumbra sign” on T1–weighted MRI for differentiating musculoskeletal infection from tumour. Skeletal Radiol 2007; 36: 417-441
• 7 Shimose S, Sugita T, Kubo T. et al. Differential diagnosis between osteomyelitis and bone tumors. Acta Radiologica 2008; 49: 928-933
• 8 Puri A, Parasnis AS, Udupa KV. et al. Fibroblastic osteosarcoma arising in chronic osteomyelitis. Clin Radiol 2003; 58: 169-171
• 9 Keel SB, Jaffe KA, Petur Neilsen G. et al. Orthopaedic implant-related sarcoma: a study of twelve cases. Mod Pathol 2001; 10: 969-977
• 10 Roe SC, DeYoung D, Weinstock D. et al. Osteosarcoma eight years after total hip arthroplasty. Vet Surg 1996; 25: 70-74
• 11 Stevenson S. Fracture-associated sarcomas. Vet Clin North Am Small Anim Pract 1991; 21: 859-872
• 12 Stevenson S, Hohn RB, Pohler OE. et al. Fracture-associated sarcoma in the dog. J Am Vet Med Assoc 1982; 180: 1189-1196
• 13 Bubenik LJ. Infections of the skeletal system. Vet Clin Small Anim 2005; 35: 1093-1109
• 14 Lascelles BDX, Dernell WS, Correa MT. et al. Improved survival associated with postoperative wound infection in dogs treated with limb-salvage surgery for osteosarcoma. Ann Surg Oncol 2005; 12: 1073-1083
• 15 Jeys LM, Grimer RJ, Carter SR. et al. Post operative infection and increased survival in osteosarcoma patients: Are they associated?. Ann Surg Oncol 2007; 14: 2887-2895.
• 16 Lee AJ, Kim MS, Kim DH. et al. Postoperative infection and survival in osteosarcoma patients. Ann Surg Oncol 2009; 16: 147-151.
• 17 Powers BE, LaRue SM, Withrow SJ. et al. Jamshidi needle biopsy for diagnosis of bone lesions in small animals. J Am Vet Med Assoc 1988; 193: 205-210.
• 18 Kim MS, Lee SY, Cho WH. et al. Prognostic effects of doctor-associated diagnostic delays in osteosarcoma. Arch Orthop Trauma Surg 2009; 129: 1421-1425.