What Is Your Diagnosis?

Patricia M. Kirby Oradell Animal Hospital, 580 Winters Ave, Paramus, NJ 07652.

Search for other papers by Patricia M. Kirby in
Current site
Google Scholar
PubMed
Close
 DVM
,
Jonathan M. Miller Oradell Animal Hospital, 580 Winters Ave, Paramus, NJ 07652.

Search for other papers by Jonathan M. Miller in
Current site
Google Scholar
PubMed
Close
 DVM
, and
Justin M. Goggin Metropolitan Veterinary Radiology Ltd, 85 Montclair Ave, Montclair, NJ 07042.

Search for other papers by Justin M. Goggin in
Current site
Google Scholar
PubMed
Close
 DVM

Click on author name to view affiliation information

History

A 10-year-old castrated male Airedale Terrier was referred for evaluation of intermittent lameness of the left hind limb that had progressed to continuous lameness of 4 days’ duration. The lameness did not resolve after treatment with NSAIDs.

Physical and orthopedic examinations revealed signs of severe hip joint pain in the left hind limb and muscle atrophy in both hind limbs. Results of a CBC were within reference ranges. Abnormalities detected on serum biochemical analysis included hyperproteinemia (protein, 7.6 g/dL; reference range, 5.0 to 7.4 g/dL) resulting from hyperglobulinemia (globulin, 4.8 g/dL; reference range, 1.6 to 3.6 g/dL), hypophosphatemia (phosphorus, 2.0 mg/dL; reference range, 2.5 to 6.0 mg/dL), and high amylase activity (1,391 U/L; reference range, 290 to 1,125 U/L). Orthogonal radiographs of the pelvis were obtained (Figure 1).

Figure 1—
Figure 1—

Lateral (A) and ventrodorsal (B) radiographic views of the pelvis of a 10-year-old castrated male Airedale Terrier evaluated because of lameness of the left hind limb.

Citation: Journal of the American Veterinary Medical Association 245, 11; 10.2460/javma.245.11.1221

Determine whether additional imaging studies are required, or make your diagnosis from Figure 1—then turn the page →

Diagnostic Imaging Findings and Interpretation

Multiple coalescing radiolucent cyst-like areas in the left ilium and left sacral wing bordering the left sacroiliac joint are evident (Figure 2). The left ilium adjacent to the cyst-like radiolucent areas is increased in opacity and sclerotic. The soft tissues of the thigh region are thin, compared with the right side. Differential diagnosis included primary neoplasia of the sacroiliac joint (chondrosarcoma, osteosarcoma, and fibrosarcoma) and, less likely, metastatic neoplasia (carcinoma).

Figure 2—
Figure 2—

Same radiographic images as in Figure 1. Notice the locally extensive radiolucent cyst-like areas centering on the sacroiliac joint (arrows). Incidental findings include small osteophytes at the margins of the left hip joint.

Citation: Journal of the American Veterinary Medical Association 245, 11; 10.2460/javma.245.11.1221

No signs of metastasis or other abnormalities were detected on 3-view thoracic radiography. Abdominal and pelvic ultrasonography revealed a thickened bladder wall; the sacroiliac region was ultrasonographically normal. Pelvic CT revealed an approximately 25-mm area of bone lysis with an epicenter in the left sacroiliac joint, consistent with a soft tissue sarcoma arising from the joint (Figure 3). No atypical cells or evidence of inflammation or infection was found on cytologic examination of a CT-guided biopsy specimen of the affected area.

Figure 3—
Figure 3—

Postcontrast transverse CT image (slice thickness, 3 mm) of the pelvis obtained at the level of the sacroiliac region and displayed in a bone window (window width, 2,500 Hounsfield units; window level, 480 Hounsfield units) of the same dog as in Figure 1. An area of bone lysis replaced by non–contrast-enhancing fluid-attenuating material centered at the left sacroiliac joint is evident (arrow).

Citation: Journal of the American Veterinary Medical Association 245, 11; 10.2460/javma.245.11.1221

Treatment and Outcome

Histologic evaluation (H&E stain) of an additional biopsy specimen of the left sacroiliac region obtained 1 month following the original lameness evaluation revealed sheets of loosely packed stellate to spindle-form neoplastic cells in pools of pale basophilic myxoid material. Histopathologic findings were consistent with a grade 2 myxosarcoma of the subcutis and bone. Because of the locally aggressive nature of the tumor, wide and complete excision of the tumor in the form of hemipelvectomy was advised, with a guarded prognosis that included possible further local destruction of soft tissue and bone. Radiation therapy was recommended for local tumor control if the tumor were to be incompletely resected or unresectable.

Further treatment was declined by the dog's owners. Radiographic evaluation of the sacroiliac region 10 months later revealed minimal progressive destruction and sclerotic bone reaction in the left ilium. Bone lysis of the ilium had not progressed radiographically. At last follow-up, the dog remained lame. The lameness was controlled by oral administration of pain medication. Although the tumor was expected to likely continue to invade the sacroiliac joint, it appeared to be slowly progressive, allowing for a better survival time than was originally expected.

Comments

Myxosarcomas are rare tumors of domestic animals.1 Myxosarcomas are malignant tumors of fibroblastic origin with an abundant myxoid matrix of mucopolysaccharides.1 They occur mostly in middle-aged or older dogs and have previously been reported to affect the skin, heart, brain, eyes, vertebral column, and jaw.1–8 To the authors’ knowledge, this is the first description of a case of myxosarcoma of the sacroiliac joint of a dog.

Radiography is typically the primary diagnostic tool when screening for tumors involving bone. Advanced imaging, such as CT or MRI, of the area is often required to evaluate tumor extent and invasiveness. Advanced imaging can also be useful for surgical planning purposes and as a method to monitor progression of the tumor. The use of MRI has been reported to be valuable in the diagnosis of myxosarcoma of the orbit.2 On MRI, lesions are typically well-defined communicating cystic areas, with contrast-enhancing fluid.2 Osteolysis of bones surrounding the tumor may also be evident in some cases.2 Although identification of fluid-filled cystic cavities in this case decreased the likelihood of certain tumor types, such as osteosarcoma, biopsy was ultimately required for diagnosis.

Histologically, these tumors can be composed of long spindle-shaped cells with homogeneously basophilic cytoplasm and spindle-shaped nuclei.3 Because of a large amount of hyaluronic acid within the mucopolysaccharide matrix, these tumors appear as a characteristic blue color when stained with Alcian blue.4 Surgical excision is the treatment of choice for myxosarcomas but can be complicated by their infiltrative nature, ill-defined margins, and likelihood of recurrence.1 Prognosis for myxosarcomas in dogs is usually good with complete excision, given that they rarely metastasize1; however, factors such as tumor location and histologic grade made prognosis guarded in this case.

  • 1. Goldschmidt MH, Hendrick MJ. Tumors of the skin and soft tissue. In: Meuten DJ, ed. Tumors in domestic animals. Iowa City, Iowa: Iowa State Press, 2002; 9192.

    • Search Google Scholar
    • Export Citation
  • 2. Dennis R. Imaging features of orbital myxosarcomas in dogs. Vet Radiol Ultrasound 2008; 49: 256263.

  • 3. Richter M, Stankeova S, Hauser B, et al. Myxosarcoma in the eye and brain in a dog. Vet Ophthalmol 2003; 6: 183189.

  • 4. Headley SA, Faria dos Reis AC, Fredrico RL, et al. Cutaneous myxosarcoma with pulmonary metastases in a dog. J Comp Pathol 2011; 145: 3134.

  • 5. Foale RD, White RA, Harley R, et al. Left ventricular myxosarcoma in a dog. J Small Anim Pract 2003; 44: 503507.

  • 6. Kunkel KAR, Palmisano MP, Stefanacci JD. Imaging diagnosis—spinal myxosarcoma in a dog. Vet Radiol Ultrasound 2007; 48: 557559.

  • 7. Galán A, Domínguez JM, Pérez J, et al. Odontogenic myxosarcoma of the jaw in a dog. Vet Rec 2007; 161: 663665.

  • 8. Craig LE, Julian ME, Ferracone JD. The diagnosis and prognosis of synovial tumors in dogs: 35 cases. Vet Pathol 2002; 39: 6673.

All Time Past Year Past 30 Days
Abstract Views 323 0 0
Full Text Views 1226 929 108
PDF Downloads 681 424 31
Advertisement