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CT/MRI

7-year-old intact male English Bulldog

February 12, 2023
Talwinderjeet Dhanjal, BVSc, rotating/general intern The Veterinary Specialty Center of Seattle-Thrive Pet Health Care
Tori McKlveen, DVM, MS, DACVR, The Veterinary Specialty Center of Seattle-Thrive Pet Healthcare
Emily D. French, DVM, DACVS-SA, The Veterinary Specialty Center of Seattle-Thrive Pet Healthcare

Two week history of left forelimb lameness

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  • A 7-year-old male intact English Bulldog presented for suspected acute trauma to his left elbow. He had a two-week history of left forelimb lameness which was first noticed after the dog fell while playing with a ball. Prescribed medications included carprofen and gabapentin.
  • On the physical exam, the dog had a grade 3/4 lameness in the left forelimb. Substantial swelling was present over the distal caudolateral humerus, to a degree such that the lateral epicondyle of the humerus was not palpable. Normal range of motion was present and while there was an occasional response to deep palpation at the caudal aspect of elbow, the dog did not appear to be overtly painful during evaluation.
  • Radiographic findings for the elbow included soft tissue swelling, joint effusion, mild chronic degenerative changes, a smooth ovoid mineralized opacity at the cranial aspect of the joint, and a focal mild periosteal reaction at the distal humeral condyles.
  • Due to the acute nature of clinical signs and the initial suspicion for a soft tissue or orthopedic injury, MRI was performed. MRI study of the left elbow included: Sagittal, axial, and dorsal T2, T1 pre and post gadolinium and FATSAT.
  • Due to the acute nature of clinical signs and the initial suspicion for a soft tissue or orthopedic injury, MRI was performed. MRI study of the left elbow included: Sagittal, axial, and dorsal T2, T1 pre and post gadolinium and FATSAT.
  • T2 hyperintense moderate joint effusion within the left elbow joint.
  • Markedly thickened and irregular, T2 hyperintense, and strongly contrast-enhancing joint capsule.
  • Ill-defined T2 hyperintense, strongly contrast-enhancing periarticular tissue.
  • T2 hyperintense, contrast enhancing signal in the regional musculature near the joint.
  • Contrast enhancing lobulated mass arising from the joint capsule at the caudal and medial aspect of the elbow joint measuring approximately 2 cm in the medial to lateral dimension-width by 3 cm in the proximal to distal dimension-height.
  • T2 and T1 very hypointense 4 mm in width by 7 mm in length elliptical foci of mineralization at the cranial aspect of the elbow joint.
  • No subchondral bone lysis.
  • Few small osteophytes on the distal humerus and proximal radius.

Moderate joint effusion, thickened and irregular joint capsule with medial mass effect, periarticular tissue enhancement and regional swelling is most suggestive of a neoplastic process. The primary differential is synovial cell sarcoma. A non-neoplastic synovitis or other inflammatory including immune-mediated or infectious process is unlikely.

  •  Synovial fluid cytology revealed neutrophilic inflammation with no neoplastic cells present. Periarticular tissue cytology was consistent with neoplasia. Cell morphology indicated synovial cell sarcoma, soft tissue sarcoma, or synovial histiocytic sarcoma.
  • Amputation was considered, however, was not elected due to breed conformation. Consultation with an oncologist was declined. The owner elected to monitor the dog’s quality of life and the dog was prescribed continued analgesics.

Based on cytology, the most likely diagnosis was sarcoma; the imaging and cytology suggest a synovial origin. Although it is rare in occurrence, synovial cell sarcoma is reported to be one of the most common neoplasms of the canine synovium. It most frequently occurs in middle-aged to older male dogs. It is a malignant mesenchymal tumor occurring at weight-bearing joints, predominantly the stifle joint followed by the elbow joint (1).  The differential diagnosis for synovial-origin tumors in dogs include histocytic sarcoma, synovial cell sarcoma, and myxoma/myxosarcoma (1).

Reference:

1. Craig, L. E., Julian, M. E., & Ferracone, J. D. (2002). The Diagnosis and Prognosis of Synovial Tumors in Dogs: 35 Cases. Veterinary Pathology, 39(1), 66-73. doi:10.1354/vp.39-1-66

 

Additional articles for review provided by CT/MRI Society-

Bedos L, Dennis R, Aertsens A. What is your diagnosis? Can Vet J. 2018 Oct;59(10):1115-1117. PMID: 30510320; PMCID: PMC6135308.

Jones BC, Sundaram M, Kransdorf MJ. Synovial sarcoma: MR imaging findings in 34 patients. AJR Am J Roentgenol. 1993 Oct;161(4):827-30. doi: 10.2214/ajr.161.4.8396848. PMID: 8396848.