What Is Your Diagnosis?

HistoryA 5-year-old neutered male Golden Retriever was evaluated because of lameness of the right forelimb of

approximately 2 months’ duration. Radiography of the right shoulder joint and forelimb revealed mild degenera-tive joint disease of the right elbow joint. The only abnormality detected on serum biochemical analyses was a highcholesterol concentration (420 mg/dL; reference range, 114 to 330 mg/dL). The dog had been treated with aspirin,carprofen, an intra-articular injection of methylprednisolone administered into the right shoulder joint, polysul-fated glycosaminoglycans, and doxycycline with no improvement in the lameness.

Physical examination revealed a weight-bearing, persistent lameness of the right forelimb, with signs of painon hyperflexion of the right shoulder joint and moderate muscle atrophy of the affected limb. Results of a CBCwere within reference limits. Results of assays for antibodies against Borrelia burgdorferi, Ehrlichia equi, andRickettsia rickettsii were negative. Results of serum biochemical analyses indicated a high cholesterol concentra-tion (435 mg/dL). Synovial fluid obtained from the right shoulder joint was submitted for cytologic examination;the cytologic diagnosis was mild degenerative joint disease. Computed tomography with contrast-mediumenhancement of the right shoulder joint and surrounding area was performed (Figure 1).

Determine whether additional imaging studies are required, or make your diagnosis from Figure 1—then turnthe page **

VETERINARY MEDICINE TODAY

Figure 1—Computed tomographic axial (A) and coronal (B) images of the right shoulder joint in a 5-year-old neutered male GoldenRetriever evaluated for lameness of the right forelimb of approximately 2 months’ duration.

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This report was submitted by Milan Milovancev, BSVS, DVM, and Ann F. Valenti, DVM; from Inver Grove Heights Animal Hospital, 7131 CahillAve, Inver Grove Heights, MN 55076. Dr. Milovancev’s present address is Veterinary Referral & Emergency Center, 123 W Cedar St, Norwalk,CT 06850.

Address correspondence to Dr. Valenti.

In cooperation with

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Diagnostic Imaging Findings and Interpretation

An irregularly shaped, irregularly contrast-enhancedmass on the craniomedial aspect of the right humerus,extending into the right axillary region, is evident (Figure2). The location of the mass is consistent with a brachialplexus tumor; however, it does not appear to continuealong the paths of the nerves of the brachial plexus.

CommentsIn this dog, diagnostic evaluation of persistent fore-

limb lameness included physical examination, radiogra-phy, CBC, serum biochemical analyses, cytologicevaluation of synovial fluid, and serum antibody assays.Results of radiography and cytologic examination of syn-ovial fluid indicated mild degenerative joint disease,which was not considered to be severe enough to causethe lameness in this dog. There was no clinical responseto treatment with carprofen, methylprednisolone, or poly-sulfated glycosaminoglycans. Chronic, persistent forelimblameness is often diagnostically challenging, and comput-ed tomography with contrast-medium enhancement ofthe affected axillary region was performed to further local-ize and define the underlying cause.

Computed tomography revealed a contrast-enhancing mass on the craniomedial aspect of the righthumerus, extending into the right axillary region.Computed tomography is useful in the preoperativediagnosis of tumors of the brachial plexus1 and is con-sidered to be superior to clinical assessment by con-ventional radiography in detecting tumor boundaries,especially with contrast-medium enhancement.2 Otherimaging modalities that are useful in localizing anddiagnosing neoplasms in dogs include magnetic reso-nance imaging3 and ultrasonography.4

Because of the high suspicion of neoplasia, theowner chose amputation of the limb with en bloc exci-sion of the associated regional lymph nodes. Histologic

evaluation of the mass revealed complete excision of alow-grade fibrosarcoma.

In dogs, the efficacy of surgical removal offibrosarcomas is affected by tumor location and mitot-ic index. Fibrosarcomas developing on a limb, such asin the dog of this report, have been associated with amedian survival time of 82 weeks and a low (7%)recurrence rate within 3 years. In dogs, fibrous tissuesarcomas with low mitotic indices are less likely toreoccur.5 Results of 1 study6 indicate that 90%, 82%,and 75% of dogs with soft tissue sarcomas were tumorfree 1, 2, and 3 years, respectively, after surgery alone.In that study, development of metastasis in dogs withlow-grade soft tissue sarcomas was low (13%), withrecurrence being most common in the lungs andregional lymph nodes.

Radiation therapy can decrease recurrence ratesfor incompletely excised lesions.7 Because of the appar-ently complete excision of the lesion and low tumorgrade, radiation therapy was not pursued in the dog ofthis report.

1. McCarthy RJ, Feeny DA, Lipowitz AJ. Preoperative diagno-sis of tumors of the brachial plexus by use of computed tomographyin three dogs. J Am Vet Med Assoc 1993;202:291–294.

2. Marincek B, Young SW. Computed tomography of sponta-neous canine neoplasms. Vet Radiol 1980;21:181–184.

3. Kippenes H, Gavin PR, Bagley RS, et al. Magnetic reso-nance imaging features of tumors of the spine and spinal cord indogs. Vet Radiol Ultrasound 1999;40:627–633.

4. Platt SR, Graham J, Chrisman CL, et al. Magnetic resonanceimaging and ultrasonography in the diagnosis of a malignant peripher-al nerve sheath tumor in a dog. Vet Radiol Ultrasound 1999;40:367–371.

5. Bostock DE, Dye MT. Prognosis after surgical excision ofcanine fibrous connective tissue sarcomas. Vet Pathol 1980;17:581–588.

6. Kuntz CA, Dernell WS, Powers BE, et al. Prognostic fac-tors for surgical treatment of soft-tissue sarcomas in dogs: 75 cases.J Am Vet Med Assoc 1997;211:1147–1151.

7. Dernell WS, Withrow SJ, Kuntz CA, et al. Principles of treat-ment for soft tissue sarcoma. Clin Tech Small Anim Pract 1998;13:59–64.

Figure 2—Same computed tomographic images as in Figure 1. Notice a contrast-enhancing mass in the right axilla (white arrows).

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