History
A 9-year-old 27-kg (59-lb) neutered male Dalmatian was evaluated because of non-weight-bearing lameness and swelling of the proximal portion of the right pelvic limb of 2 weeks' duration. The dog had had a similar episode 6 weeks previously, which had resolved over a period of 2 weeks when treated with an NSAID and cold-packing of the limb.
Clinical and Gross Findings
The caudal aspect of the right thigh was swollen and firm; palpation elicited signs of pain. Serum biochemical analyses revealed high alkaline phosphatase activity (304 U/L; reference range, 20 to 157 U/L). Ultrasonography of the right pelvic limb revealed a 9-cm-long, oval, cavitated mass of mixed echogenicity in the caudal aspect of the thigh, but fine-needle aspiration of the mass yielded only blood. Thoracic radiographic and abdominal ultrasonographic findings were unremarkable. In the following 3 weeks after treatment with NSAIDs, the limb regained its normal size; however, the dog was returned 28 days later with recurrence of the swelling (Figure 1). At this time, the intracompartmental pressures in the lateral and caudal right thigh musculature, measured by use of a technique previously described,1 were 23 and 70 mm Hg (reference range,2 −2 to 8 mm Hg), respectively, consistent with compartment syndrome (CS). Concurrently, an automated blood pressure monitor was used to measure blood pressure; the mean systolic arterial blood pressure was 168 mm Hg, and the mean diastolic arterial blood pressure was 100 mm Hg.
Photographs of the caudal aspect of the right pelvic limb (A) and cross-sectional view of the right thigh musculature (as seen at necropsy [B]) of a Dalmatian that had non-weight-bearing lameness and swelling of the proximal portion of the right pelvic limb of 2 weeks' duration. In the antemortem view, notice the large swelling of the caudal thigh musculature of the right pelvic limb. In the cross-sectional view of the right thigh musculature, notice the large, cavitated mass that has compressed and incorporated caudal thigh muscle tissue. The mass was composed of a cranial cavitated area filled with clotted blood and fibrin (hematoma [1]) and a caudal yellow-tan, gelatinous area (necrotic adipose tissue [2]). Lat = Lateral aspect. Med = Medial aspect. a = Adductor muscle. b = Biceps femoris muscle. f = Femur. g = Gracilis muscle. q = Quadriceps femoris muscles. Bar in panel B = 1 cm.
Citation: Journal of the American Veterinary Medical Association 253, 7; 10.2460/javma.253.7.861
Photographs of the caudal aspect of the right pelvic limb (A) and cross-sectional view of the right thigh musculature (as seen at necropsy [B]) of a Dalmatian that had non-weight-bearing lameness and swelling of the proximal portion of the right pelvic limb of 2 weeks' duration. In the antemortem view, notice the large swelling of the caudal thigh musculature of the right pelvic limb. In the cross-sectional view of the right thigh musculature, notice the large, cavitated mass that has compressed and incorporated caudal thigh muscle tissue. The mass was composed of a cranial cavitated area filled with clotted blood and fibrin (hematoma [1]) and a caudal yellow-tan, gelatinous area (necrotic adipose tissue [2]). Lat = Lateral aspect. Med = Medial aspect. a = Adductor muscle. b = Biceps femoris muscle. f = Femur. g = Gracilis muscle. q = Quadriceps femoris muscles. Bar in panel B = 1 cm.
Citation: Journal of the American Veterinary Medical Association 253, 7; 10.2460/javma.253.7.861
Photographs of the caudal aspect of the right pelvic limb (A) and cross-sectional view of the right thigh musculature (as seen at necropsy [B]) of a Dalmatian that had non-weight-bearing lameness and swelling of the proximal portion of the right pelvic limb of 2 weeks' duration. In the antemortem view, notice the large swelling of the caudal thigh musculature of the right pelvic limb. In the cross-sectional view of the right thigh musculature, notice the large, cavitated mass that has compressed and incorporated caudal thigh muscle tissue. The mass was composed of a cranial cavitated area filled with clotted blood and fibrin (hematoma [1]) and a caudal yellow-tan, gelatinous area (necrotic adipose tissue [2]). Lat = Lateral aspect. Med = Medial aspect. a = Adductor muscle. b = Biceps femoris muscle. f = Femur. g = Gracilis muscle. q = Quadriceps femoris muscles. Bar in panel B = 1 cm.
Citation: Journal of the American Veterinary Medical Association 253, 7; 10.2460/javma.253.7.861
Computed tomography of the right pelvic limb revealed no evidence of bone lysis. Under anesthesia, multiple incisional biopsies were performed; examination of the collected specimens yielded a definitive diagnosis. Given the dog's poor prognosis, hind limb amputation was declined and euthanasia (by means of IV administration of euthanasia solution) was elected; permission for a necropsy was granted. The right caudal thigh semimembranosus and semitendinosus musculature was compressed by and incorporated into a heterogeneous mass. The mass was composed of a cranial cavitated area filled with clotted blood and fibrin and a caudal yellow-tan, gelatinous area. The lungs had multiple, dark red, slightly raised, spherical (1- to 2-mm-diameter) nodules scattered throughout all lobes. No other organs were involved.
Formulate differential diagnoses from the history, clinical findings, and Figure 1—then turn the page →
Histopathologic Findings
Histologically, the biopsy and necropsy samples of the right thigh muscle mass consisted of large areas of fibrin and hemorrhage (hematoma) variably mixed with hemosiderin-laden macrophages and necrotic cell debris and marginated by neoplastic mesenchymal cells lining irregular vascular clefts and channels interspersed by solid aggregates. Neoplastic cells were spindle shaped to polygonal and had scant eosinophilic cytoplasm and round to oval, moderately pleomorphic nuclei with 1 to 3 nucleoli (Figure 2). Adjacent muscle fascicles had increased amounts of fibrous connective tissue and muscle fibers with reduced size, consistent with atrophy. The histologic features of the muscle mass were consistent with primary hemangiosarcoma, and the lung nodules were confirmed histologically as metastatic hemangiosarcoma. No other organs were involved.
Photomicrograph of a section of a biopsy specimen collected from the affected portion of the right pelvic limb of the dog in Figure 1. Notice the irregular vascular clefts and channels lined by plump neoplastic mesenchymal cells, which also form solid aggregates (arrow). Skeletal muscle, variably dissected and replaced by neoplastic cells, is present in the periphery (asterisk). H&E stain; bar = 50 μm.
Citation: Journal of the American Veterinary Medical Association 253, 7; 10.2460/javma.253.7.861
Photomicrograph of a section of a biopsy specimen collected from the affected portion of the right pelvic limb of the dog in Figure 1. Notice the irregular vascular clefts and channels lined by plump neoplastic mesenchymal cells, which also form solid aggregates (arrow). Skeletal muscle, variably dissected and replaced by neoplastic cells, is present in the periphery (asterisk). H&E stain; bar = 50 μm.
Citation: Journal of the American Veterinary Medical Association 253, 7; 10.2460/javma.253.7.861
Photomicrograph of a section of a biopsy specimen collected from the affected portion of the right pelvic limb of the dog in Figure 1. Notice the irregular vascular clefts and channels lined by plump neoplastic mesenchymal cells, which also form solid aggregates (arrow). Skeletal muscle, variably dissected and replaced by neoplastic cells, is present in the periphery (asterisk). H&E stain; bar = 50 μm.
Citation: Journal of the American Veterinary Medical Association 253, 7; 10.2460/javma.253.7.861
Morphologic Diagnosis and Case Summary
Morphologic diagnosis: intramuscular hemangiosarcoma with myositis, necrosis, atrophy, and fibrosis of the right caudal thigh region.
Case summary: femoral CS and recurrent pelvic limb swelling secondary to intramuscular hemangiosarcoma in a dog.
Comments
The dog of the present report had primary muscle hemangiosarcoma that resulted in recurrent episodes of muscle swelling and CS. These episodes were presumed to be associated with episodic hemorrhage and subsequent blood resorption, as seen in cases of visceral hemangiosarcoma.3
Osteofascial CS is defined as increased pressure within an anatomic space limited by bone and fascia, resulting in local neuromuscular ischemia.2 The femoral compartment, which was affected in the dog of the present report, is a complex structure comprised of multiple fascial planes separately incorporating the quadriceps femoris, hamstring (biceps femoris, semitendinosus, and semimembranosus), and adductor muscles. The increase in intracompartmental pressure is believed to be a consequence of increased interstitial hydrostatic fluid pressure, usually as a result of hemorrhage or edema fluid accumulation. Ischemic necrosis of intracompartmental and adjacent tissues ensues, resulting in permanent neuromuscular dysfunction if left unchecked. In the case described in the present report, necrosis of intralesional tissues was apparent and surrounding tissues were compressed and atrophied.
In dogs, muscle tissue has been shown to undergo ischemic necrosis at pressures 20 mm Hg lower than diastolic arterial blood pressure.4 In general, however, absolute pressures > 30 mm Hg sustained for 8 hours correspond with a reduced prognosis for return to function without emergency fasciotomy.5 The compartment pressure of 70 mm Hg in the caudal thigh musculature of the dog of the present report was 30 mm Hg lower than the concurrent mean diastolic arterial blood pressure, yet was higher than values previously described for clinical cases of CS in dogs.1,2,6,7 Abnormal intracompartmental pressures of 25 to 28 mm Hg6 and 30 mm Hg6 in dogs with intramuscular hemangiosarcoma have been documented, and pressures of 15 to 30 mm Hg7 and 41 mm Hg2 in dogs with traumatic injuries have been detected. Compartment syndrome has also been diagnosed without adjunctive intracompartmental pressure measurement.8,9
Primary hemangiosarcoma of skeletal muscle in dogs is sporadically reported,1,2,6,7–12 and only 2 reports5,6 specifically describe CS in association with this neoplasm. A third report13 describes CS in 2 dogs as a consequence of a mast cell tumor or presumptive sarcoma. Intramuscular hemangiosarcoma therefore appears to be uncommon in dogs. Other differential diagnoses for intramuscular mass-like lesions would include rhabdomyosarcoma, rhabdomyoma, fibrosarcoma, lymphoma, infiltrative lipoma, hematoma, and pseudotumor.14
References
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4. Matava MJ, Whitesides TE Jr, Seiler JG, et al. Determination of the compartment pressure threshold of muscle ischemia in a canine model. J Trauma 1994;37:50–58.
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6. Bar-Am Y, Anug AM, Shahar R. Femoral compartment syndrome due to haemangiosarcoma in the semimembranosus muscle in a dog. J Small Anim Pract 2006;47:286–289.
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10. Tucker DW, Olsen D, Kraft SL, et al. Primary hemangiosarcoma of the iliopsoas muscle eliciting a peripheral neuropathy. J Am Anim Hosp Assoc 2000;36:163–167.
11. Wray JD, Bestbier M, Miller J, et al. Aortic and iliac thrombosis associated with angiosarcoma of skeletal muscle in a dog. J Small Anim Pract 2006;47:272–277.
12. Pearson GR, Head KW. Malignant haemangioendothelioma (angiosarcoma) in the dog. J Small Anim Pract 1976;17:737–745.
13. Maki LC, Kim SE, Winter MD, et al. Compartment syndrome associated with expansile antebrachial tumors in two dogs. J Am Vet Med Assoc 2014;244:346–351.
14. Van Vleet JF, Valentine BA. Muscle and tendon. In: Maxie MG, ed. Jubb, Kennedy, and Palmer's pathology of domestic animals. Volume 1. 5th ed. Edinburgh: Elsevier Saunders, 2007;185–280.
