Surgical excision of a malignant metastatic melanoma located in a skeletal muscle of the lateral thorax of a horse

BACKGROUND

A 20-year-old grey Warmblood gelding that had history of dermal melanomatosis.

OBJECTIVE

To report surgical treatment of a 6-cm large malignant metastatic melanoma located in the cutaneous trunci muscle of the left lateral thorax of a horse.

METHODS

A 20-year-old grey Warmblood gelding was referred for evaluation of a large, rapidly growing, thoracic mass. Clinical examination revealed an ovoid, firm, non-painful, movable mass, approximately 6 cm in diameter, located in the cutaneous trunci muscle of the left lateral thorax. Multiple melanocytic nodules were also found at the perianal region and ventral tail. Rectal examination, ultrasonography and endoscopy of the respiratory tract revealed no melanomas internally. Haematological and biochemical values were within normal limits. Surgical excision of both the thoracic mass and perianal nodules was the treatment of choice. Histopathology of the distant thoracic mass confirmed the diagnosis of malignant metastatic melanoma secondary to the perineal lesions that were confirmed as dermal melanomatosis.

RESULTS

The horse recovered uneventfully. Up until 3 years post surgery there was no tumour regrowth at the excision sites.

CONCLUSION

Surgical excision of the metastatic melanoma was performed and considered successful, with no gross evidence of tumour reoccurrence. Despite the fact that surgical excision is considered a treatment option regarding equine dermal melanomatosis, there is no previously published study proposing surgical removal of distant malignant metastatic melanocytic masses. This is the first report of a successful surgical excision of a large (6 cm) metastatic melanocytic tumour from the skeletal muscle of the lateral thorax of a horse.

Kilovoltage radiotherapy for companion animals: dosimetric comparison of 300 kV, 450 kV, and 6 MV X-ray beams

Radiotherapy for the treatment of cancer in companion animals is currently administered by using megavoltage X-ray machines. Because these machines are expensive, most animal hospitals do not perform radiotherapy. This study evaluated the ability of relatively inexpensive kilovoltage X-ray machines to treat companion animals. A simulation study based on a commercial treatment-planning system was performed for tumors of the brain (non-infectious meningoencephalitis), nasal cavity (malignant nasal tumors), forefoot (malignant muscular tumors), and abdomen (malignant intestinal tumors). The results of kilovoltage (300 kV and 450 kV) and megavoltage (6 MV) X-ray beams were compared. Whereas the 300 kV and 6 MV X-ray beams provided optimal radiation dose homogeneity and conformity, respectively, for brain tumors, the 6 MV X-rays provided optimal homogeneity and radiation conformity for nasal cavity, forefoot, and abdominal tumors. Although megavoltage X-ray beams provided better radiation dose distribution in most treated animals, the differences between megavoltage and kilovoltage X-ray beams were relatively small. The similar therapeutic effects of the kilovoltage and 6 MV X-ray beams suggest that kilovoltage X-ray beams may be effective alternatives to megavoltage X-ray beams in treating cancers in companion animals.

Rhabdomyosarcoma in a Silver Carp

Rhabdomyosarcoma is a primitive neoplasm that originates from skeletal muscle progenitor cells. In a routine inspection of a cyprinid farm in southwestern Iran, an approximately 2-year-old female Silver Carp was observed to have a raised mass located on the dorsolateral surface just caudal to the head. Macroscopic examination revealed a firm irregular fleshy pink mass (5 × 4 cm, depth = 3 cm) that appeared to arise from the subcutaneous musculature. Histologic sections were prepared using routine methods and separate sections were stained with hematoxylin-eosin and Massons' trichrome. Microscopically, the tumor mass was composed of spindle cells that were densely packed and arranged in long interwoven bundles. The nuclei were vesicular and oval to elongated or cigar-shaped. Nuclear pleomorphism and multinucleate tumor giant cells were clearly evident. The neoplastic cell cytoplasm was eosinophilic with indistinct cell margins, and clear cross striations were observed in fibrils. The striated fibrils stained diffusely red with Masson's trichrome. This account represents the first reported occurrence of rhabdomyosarcoma in Silver Carp Hypophthalmichthys molitrix. Received July 10, 2015; accepted February 4, 2016.

Metastasized Leydig cell tumor in a dog

We present the clinical findings, diagnosis and treatment of an 11-year old intact male Fox Terrier with a malignant Leydig cell tumor of the right testicle, which metastasized to the skeletal musculature of the left hind limb. The primary tumor and the metastasis were resected with narrow margins. The dog was treated with metronomic chemotherapy using thalidomid and dyclophosphamide. Local recurrence at the site of the metastasis and a pulmonary metastasis were present 30 months after surgery. The dog was euthanized.

Spontaneous osteoblastic osteosarcoma in a Mongolian gerbil (Meriones unguiculatus)

Spontaneous neoplasms in Mongolian gerbils have an incidence of 20% to 26.8%, but osteosarcomas occur at a much lower rate. Here we report a 1-y-old Mongolian gerbil with a spontaneous osteosarcoma at the level of the proximal tibia, with metastases to the pectoral muscles and lungs. Grossly, the tibial mass obliterated the tibia and adjacent muscles, and an axillary mass with a bloody, cavitary center expanded the pectoral muscles. Microscopically, the tibial mass was an infiltrative, osteoblastic mesenchymal neoplasm, and the axillary mass was an anaplastic mesenchymal neoplasm with hemorrhage. The lung contained multiple metastatic foci. Immunohistochemistry for osteonectin was strongly positive in the tibial, axillary, and pulmonary metastases. Although osteosarcoma is the most common primary malignant bone neoplasm that occurs spontaneously in all laboratory and domestic animal species and humans, it arises less frequently than does other neoplasms. The current case of spontaneous osteoblastic osteosarcoma of the proximal tibia and metastases to the pectoral muscles and lung in a Mongolian gerbil is similar in presentation, histology, and predilection site of both osteoblastic and telangiectatic osteosarcomas in humans. In addition, this case is an unusual manifestation of osteosarcoma in the appendicular skeleton of a Mongolian gerbil.

Chemotherapy and radiation therapy in 4 dogs with muscle-invasive transitional cell carcinoma of the urinary tract

Four dogs with T(2)N(0)M(0) transitional cell carcinoma of the lower urinary tract underwent multimodal treatment consisting of neoadjuvant chemotherapy, external-beam radiotherapy, and adjuvant chemotherapy. No significant toxicity was documented. All dogs showed clinical improvement and reduction of tumor volume based on computed tomography (CT).

Preclinical evaluation of oncolytic vaccinia virus for therapy of canine soft tissue sarcoma

Virotherapy using oncolytic vaccinia virus (VACV) strains is one promising new strategy for canine cancer therapy. In this study we describe the establishment of an in vivo model of canine soft tissue sarcoma (CSTS) using the new isolated cell line STSA-1 and the analysis of the virus-mediated oncolytic and immunological effects of two different Lister VACV LIVP1.1.1 and GLV-1h68 strains against CSTS. Cell culture data demonstrated that both tested VACV strains efficiently infected and destroyed cells of the canine soft tissue sarcoma line STSA-1. In addition, in our new canine sarcoma tumor xenograft mouse model, systemic administration of LIVP1.1.1 or GLV-1h68 viruses led to significant inhibition of tumor growth compared to control mice. Furthermore, LIVP1.1.1 mediated therapy resulted in almost complete tumor regression and resulted in long-term survival of sarcoma-bearing mice. The replication of the tested VACV strains in tumor tissues led to strong oncolytic effects accompanied by an intense intratumoral infiltration of host immune cells, mainly neutrophils. These findings suggest that the direct viral oncolysis of tumor cells and the virus-dependent activation of tumor-associated host immune cells could be crucial parts of anti-tumor mechanism in STSA-1 xenografts. In summary, the data showed that both tested vaccinia virus strains and especially LIVP1.1.1 have great potential for effective treatment of CSTS.

Microchip-associated leiomyosarcoma in an Egyptian fruit bat (Rousettus aegyptiacus)

Microchips are commonly used in companion, research, and zoo animal medicine for easy, reliable, and cost-effective identification with relatively low risk of side effects. This report describes development of a metastatic leiomyosarcoma associated with a microchip in an Egyptian fruit bat (Rousettus aegyptiacus).

Reclassification of Small Intestinal and Cecal Smooth Muscle Tumors in 72 Dogs: Clinical, Histologic, and Immunohistochemical Evaluation

OBJECTIVES

To reclassify canine small intestinal and cecal leiomyoma (LM) and leiomyosarcoma (LMS) into smooth muscle and gastrointestinal stromal tumors (GIST) using histologic and immunohistochemical (IH) analysis and to report clinical findings and survival data.

STUDY DESIGN

Retrospective review of cases.

ANIMALS

Dogs (n=47) with small intestinal (40 LMS; 7 LM) and 25 dogs with cecal tumors (23 LMS; 2 LM).

METHODS

Clinical and survival data were reviewed. Tissue sections were reevaluated for light-microscopic malignancy criteria and examined for expression of SMA, desmin, vimentin, S-100, and CD117 (KIT) by immunohistochemistry.

RESULTS

Reclassification resulted in 2 LM, 9 LMS, 19 GIST, and 17 GIST-like tumors in the small intestine and 23 GIST and 2 GIST-like tumors in the cecum. GIST-like tumors were morphologic and IH identical to GIST but lacked KIT expression. No significant difference in survival was observed for tumor type, location, histologic, or IH characteristics; however, dogs with cecal tumors were significantly older in age, presented more commonly with intestinal perforation and peritonitis, and less commonly with weight loss. Cecal tumors had more histologic malignancy criteria than small intestinal tumors. After excision, 1 and 2 year recurrence-free periods were 80.1% and 67.2% for small intestinal and 83.3% and 61.9% for cecal tumors.

CONCLUSION

Prognosis for intestinal tumors with histologic smooth muscle appearance is good after excision and not related to tumor type, location, histologic, or IH characteristics.

CLINICAL RELEVANCE

Clinical importance could not be demonstrated for reclassification, but may be for future treatment, of intestinal smooth muscle or stromal tumors.

Adenocarcinoma metastasis of the intertransversarius cervicis muscle eliciting a right forelimb lameness in a dog

This article describes identification of a metastatic adenocarcinoma to the intertransversarius cervicis muscle using magnetic resonance imaging (MRI) in a dog that presented with chronic lameness of the right forelimb. Magnetic resonance imaging revealed a right sided, ovoid signal abnormality within the intertransversarius cervicis muscle lateral to the sixth cervical (C6) vertebra. The lesion was uniform, hyperintense on T2- and isointense on T1-weighted images to muscle and exhibited uniform contrast enhancement on T1-weighted images. The MRI findings were consistent with a neoplasia. Surgical excision was performed. Histopathological diagnosis was metastatic fibrous adenocarcinoma. The dog recovered rapidly but 6 months post-operatively he was killed because of lung metastases. Necropsy was declined and the primary tumour could not be identified.

Hemidiaphragmatic reconstruction with a transversus abdominis muscle flap after resection of a solitary diaphragmatic mesothelioma in a dog

CASE DESCRIPTION

A 2-year-old Siberian Husky was evaluated because of a 2-week history of coughing and gagging and decreased appetite and activity level.

CLINICAL FINDINGS

Radiography, surgery, and immunohistochemical examination revealed a solitary sclerosing mesothelioma extending from the left thoracic diaphragmatic surface that was adherent to the pericardium and the caudal mediastinum.

TREATMENT AND OUTCOME

The tumor was resected along with most of the left hemidiaphragm, and the left transversus abdominis muscle was used to reconstruct the diaphragm. The 13th rib formed the base of the muscle flap. The muscle flap was transposed into the defect so that the mesothelium-lined surface faced the thoracic cavity and the deep aspect of the muscle formed the abdominal surface of the diaphragm. To minimize risk of adhesions, the exposed raw aspect of the abdominal surface was covered with porcine small intestinal submucosa. Recovery was uncomplicated, and the dog's appetite and activity level soon returned to normal. Evaluation 54 days after surgery revealed 2 subcutaneous masses on the thorax and masses in the liver and both kidneys; histologic and immunohistochemical analyses revealed metastasis of the original tumor. The dog was euthanatized.

CLINICAL RELEVANCE

Hemidiaphragmatic reconstruction with a transversus abdominis muscle flap after resection of a diaphragmatic tumor was successful. The muscle flap was easily harvested and transposed into the diaphragmatic defect.

Acute compartment syndrome complicating an intramuscular haemangiosarcoma in a dog

Acute compartment syndrome in dogs is a rare complication of muscle trauma, but it has not been previously reported as a consequence of neoplasia in dogs. This case report describes the occurrence of a compartment syndrome of the femoral compartment in an 11-year-old, male, mixed-breed dog caused by acute bleeding of an intramuscular haemangiosarcoma. The compartment syndrome was relieved by immediate fasciotomy. The dog was euthanased following acute recurrence of clinical signs seven weeks after surgery.

Femoral compartment syndrome due to haemangiosarcoma in the semimembranosus muscle in a dog

A five-year-old, entire male German shepherd dog was presented to the Veterinary Teaching Hospital-Koret School of Veterinary Medicine because of an acute, painful swelling of the right thigh and severe lameness of two-weeks duration. On physical examination, a firm and painful mass was detected in the hamstring region. Radiography and ultrasonography revealed a soft tissue mass, with a 250 cc fluid accumulation craniomedial to it. Intracompartmental pressure measurement with a Wick catheter demonstrated significantly elevated pressure within the right caudal femoral compartment (25 to 28 mmHg compared with 5 to 7 mmHg in the unaffected leg). Surgical exploration of the area was undertaken, fasciotomy and mass excision were performed, and resolution of the clinical signs was achieved. The mass was identified by histopathology results as haemangiosarcoma. Two and a half months after surgery, which was followed by adjunct chemotherapy (doxorubicin), the dog was readmitted with a subcutaneous mass in the same area, although he was not lame at this time. Radiographs of the thoracic cavity demonstrated widely disseminated metastases in the lungs. At that point, the owner elected to have the dog euthanased.

Aortic and iliac thrombosis associated with angiosarcoma of skeletal muscle in a dog

A seven-year-old, neutered male greyhound was presented with a history of episodic shifting hindlimb lameness and pain. Ischaemic necrosis of areas of the hindlimb digits and skin and a firm swelling within the medial right thigh musculature were found on physical examination. Investigation demonstrated thrombosis of the terminal aorta and right external iliac artery with ischaemic necrosis of muscular and dermal tissue distal to the sites of thrombosis. The dog was euthanased due to poor prognosis. Necropsy findings were of a poorly differentiated invasive sarcoma of the skeletal muscle of the proximal right hindlimb, thrombosis of the aorta and right external iliac artery and secondary renal glomerulopathy. Immunohistochemistry of the neoplastic tissue indicated angiosarcoma based on expression of CD31 and factor VIII-related antigen. Thrombosis was considered likely to be due to systemic hypercoagulability because of the presence of altered flow characteristics and endothelial damage in the vascular tumour bed. Aortoiliac thrombosis, paraparesis and hindlimb ischaemia are unusual sequelae of angiosarcoma in the dog.

Common malignant musculoskeletal neoplasms of dogs and cats

Malignancies of the musculoskeletal system in dogs and cats can be categorized as either primary or metastatic within the bony or soft structures that comprise the musculoskeletal system. By far, the most common tumor that affects the musculoskeletal system in dogs is osteosarcoma. The most common tumors that affect the musculoskeletal system in cats are injection site sarcomas. These tumors are locally infiltrative; whereas up to 25% metastasize, most animals die from our inability to control local disease. The aim of this article is to provide a brief review of the biologic behavior of and treatment recommendations for common tumors of the musculoskeletal system, excluding the oral and nasal cavities.

Canine transmissible venereal tumor: a large-animal transplantable tumor model

The canine transplantable venereal tumor is a naturally occurring transplantable round-cell tumor in dogs. Although experimental transplantable tumor models in rodents and rabbits are readily available, a reliable transplantable tumor model in a large animal that more closely resembles the physical dimensions of humans has not been available. A tumor model in a large animal would have a wide range of biomedical research applications, including the study of various interventional imaging techniques. In this report, we characterize the experimental transplantation of the canine transmissible venereal tumor in the brain, skin, muscle, prostate, lung, liver, and bone of dogs and provide X-ray computed tomographic and magnetic resonance imaging characteristics of the tumors in the brain, muscle, lung, and prostate.

Embedded weapons-grade tungsten alloy shrapnel rapidly induces metastatic high-grade rhabdomyosarcomas in F344 rats

Continuing concern regarding the potential health and environmental effects of depleted uranium and lead has resulted in many countries adding tungsten alloy (WA)-based munitions to their battlefield arsenals as replacements for these metals. Because the alloys used in many munitions are relatively recent additions to the list of militarily relevant metals, very little is known about the health effects of these metals after internalization as embedded shrapnel. Previous work in this laboratory developed a rodent model system that mimicked shrapnel loads seen in wounded personnel from the 1991 Persian Gulf War. In the present study, we used that system and male F344 rats, implanted intramuscularly with pellets (1 mm times 2 mm cylinders) of weapons-grade WA, to simulate shrapnel wounds. Rats were implanted with 4 (low dose) or 20 pellets (high dose) of WA. Tantalum (20 pellets) and nickel (20 pellets) served as negative and positive controls, respectively. The high-dose WA-implanted rats (n = 46) developed extremely aggressive tumors surrounding the pellets within 4-5 months after implantation. The low-dose WA-implanted rats (n = 46) and nickel-implanted rats (n = 36) also developed tumors surrounding the pellets but at a slower rate. Rats implanted with tantalum (n = 46), an inert control metal, did not develop tumors. Tumor yield was 100% in both the low- and high-dose WA groups. The tumors, characterized as high-grade pleomorphic rhabdomyosarcomas by histopathology and immunohistochemical examination, rapidly metastasized to the lung and necessitated euthanasia of the animal. Significant hematologic changes, indicative of polycythemia, were also observed in the high-dose WA-implanted rats. These changes were apparent as early as 1 month postimplantation in the high-dose WA rats, well before any overt signs of tumor development. These results point out the need for further studies investigating the health effects of tungsten and tungsten-based alloys.

Osteosarcoma with multiple metastases and subcutaneous involvement in a rabbit (Oryctolagus cuniculus)

BACKGROUND

Osteogenic sarcomas are rare in rabbits, but cases involving the mandible, ribs, frontal bones, and tibia have been reported.

OBJECTIVE

The purpose of this study was to describe the clinical and pathologic findings in a rabbit with osteosarcoma and multiple metastases with subcutaneous involvement.

METHODS

A 1-year-old female Polish rabbit was evaluated for dysorexia, lameness, gait difficulties with the hind limbs, and the presence of 2 subcutaneous nodules, on the left thigh and in the dorsal region. A hard swelling was also present at the base of the tail. Radiographic findings revealed multiple abnormalities in several bones, which were more severe in the sacrococcygeal region and femur. Several areas of calcification involving the thorax and abdomen as well as skeletal muscles, also were noted. The thigh nodule was surgically removed, and cytologic and histologic evaluations were performed. Following the rabbit's death, postmortem radiographs were taken and necropsy was performed. Samples of tissues and organs, involved bone segments, and other subcutaneous nodules were collected and examined by cytology and histology.

RESULTS

Both the subcutaneous nodules and the majority of tissues and organs contained neoplastic cells whose appearance was consistent with osteogenic sarcoma.

CONCLUSION

Clinical, radiologic, and pathologic data supported a diagnosis of osteosarcoma with multiple metastases and subcutaneous involvement.

Metastatic squamous cell carcinoma in two loggerhead sea turtles Caretta caretta

We received 2 stranded loggerhead sea turtles (Caretta caretta) with squamous cell carcinomas to necropsy. The dead turtles had been collected in Gran Canaria and Fuerteventura in April 1994 and May 1997, respectively to determine the cause of death. One turtle had 3 ulcerated lesions in the dorsal part of the neck and several irregular masses in the lungs and kidneys. Histologic examination of lesions in the skin, lungs, kidneys, and ventricular myocardium revealed neoplastic proliferation of abnormal keratinocytes. Ultrastructural examination identified the tumoral cells as epithelial cells. The second turtle had 4 lesions in the skin of the head and flippers, and several irregular masses in the lungs, liver, and kidneys. Histological examination revealed a squamous cell carcinoma with metastases to muscle tissue, liver, lungs, and kidneys. Attempts to characterize the tumoral cells by immunohistochemistry using several monoclonal and polyclonal antisera against high and low molecular weight cytokeratins from mammals, as well as vimentin and desmin, failed. Differences between reptilian keratins (mainly beta-keratins) and mammalian keratins (mainly alpha-keratins) could explain this absence of immunoreactivity. This is the first description of squamous cell carcinoma in sea turtles.

Pleomorphic rhabdomyosarcoma with pulmonary metastasis in a stranded Steller (northern) sea lion (Eumetopias jubatus)

A Steller (northern) sea lion (SSL), stranded in northern California in July 2000 had an anaplastic pleomorphic rhabdomyosarcoma in the latissimus dorsi muscle, with pulmonary metastasis. Diagnosis was based on light and electron microscopy and immunohistochemistry. Death was attributed to multiple parasitic and bacterial lesions. The SSL is of special concern because, for unknown reasons, the global population has declined by 50% over the last decade. Published post-mortem data, however, are scarce. This case report highlights several disease conditions that affect this species and is the first report of a malignant neoplasm in a free-ranging SSL.

A Malar Granular Cell Tumor in a Djungarian Hamster

'Granular cell' tumor observed in the malar subcutis of a Djungarian hamster was examined to determine its cellular origin. Histologically, the tumor consisted of a solid growth of oval or spindle-shaped large cells with abundant cytoplasm filled with eosinophilic granules that were periodic acid-Schiff-positive and diastase-resistant. Immunohistochemically, the tumor cells were positive to anti-vimentin and anti-desmin antibodies and a few cells showed positivity to anti-actin antibody as well. They did not react to myoglobin, S-100 protein, and glial fibrillary acidic protein (GFAP). Electron microscopic studies revealed that the tumor cells had pinocytotic vesicles, dense plaque and microfilaments. The first granular cell variant of myogenic tumor reported here in Djungarian hamsters was differentiated from granular cell tumor of Schwann cell origin.

Evaluation of porfimer sodium in dogs and cats with spontaneous tumors

The effect of photodynamic therapy is a function of several variables, including selective retention of the drug in tumor tissue with reduced drug concentration in surrounding normal tissue. A study was designed to determine the pharmacokinetic profile and variability of porfimer sodium in dogs and cats with spontaneous tumors and to thereby determine the optimal timing of its photoactivation in these species. The results of this study indicate that there is marked variability among species in the distribution of porfimer sodium between highly proliferating tissues, which requires careful attention in the design of human and veterinary application of photodynamic therapy with porfimer sodium, as determined in rodent models.

Congenital melanoma in a heifer

The clinical, intra-operative and pathological findings taken from a case of melanoma in a 9-month-old female Holstein Friesian heifer are reported here. The tumor, hanging on the right side of the thorax, was present at birth and increased in size with time. Muscular invasion by tumoral tissue was detected during surgery. Histological and cytological data indicated that the neoplasia (melanocytoma) was benign but the prognosis, related to the invasiveness of this neoplasm, was considered reserved. Melanoma is a rare tumor in cattle, often congenital, although already reported in pigs and in horses.

Surgical management of haemangiopericytoma involving the biceps femoris muscle in four dogs

Four dogs with haemangiopericytoma of the subcutaneous tissue overlying and infiltrating the biceps femoris muscle were successfully managed using complete resection of the involved muscle with 2 to 3 cm skin margins. Postoperatively, no local recurrence was noted in any of the dogs in a follow-up period of four to 33 months (mean 22 months). Wound dehiscence, attributed to increased tension and inadequate exercise restriction, occurred in two of the four cases. Closure of the large cutaneous deficit in the craniolateral thigh and stifle was achieved by rotation of a flank-fold skin flap in one case. Strict exercise restriction and the use of a Robert Jones dressing may prevent muscle suture disruption. These measures should enable primary wound healing in the region to progress without complication.

Angiographic study and therapeutic embolization of soft-tissue fibrosarcoma in a dog: case report and literature

A case of soft-tissue fibrosarcoma with pulmonary metastases in a dog is reported. Although three attempts of fine-needle aspiration (FNA) biopsy failed to provide definitive tumor diagnosis, results of angiography strongly indicated a soft-tissue sarcoma. Transcatheter arterial embolization (TAE) using particles of gelatin sponge was performed following selective angiography. The mass was decreased in size on reevaluation 2 weeks after embolization. The dog was euthanized on the request of the owners due to overall failing health. Necropsy and pathological study confirmed the diagnosis of soft-tissue fibrosarcoma with pulmonary metastases. In a review of the literature, angiographic findings of soft-tissue sarcoma in the dog of this report were similar to those in human beings, suggesting a potential role for angiography in the differential diagnosis of suspect soft-tissue fibrosarcomas and for guiding FNA or surgical biopsy. Previous reports have also shown therapeutic embolization to be an effective treatment both in experimental animal study and in clinical practice in the human; therefore, TAE could be an effective adjunctive treatment of soft-tissue fibrosarcoma in the dog.

Metastatic pulmonary adenocarcinoma in a llama (Lama glama)

An adult female llama with a comminuted fracture of the left femoral head was necropsied. A firm multinodular mass infiltrated skeletal muscle adjacent to the fracture. Multiple, firm, white nodules were in the pulmonary parenchyma and pleura. A single nodule was in the liver. Microscopically, transition from nonneoplastic bronchiolar epithelium to neoplastic epithelium that formed acinar structures was evident at bronchioloalveolar junctions. A diagnosis of pulmonary adenocarcinoma was made. Similar neoplastic tissue was in the liver and in the perifemoral mass. Immunohistochemically, neoplastic cells were positive for pan-cytokeratin, cytokeratin 7, and cytokeratin 5/6 antibodies and negative for vimentin and cytokeratins 8/18 and 20.

Radical lateral body-wall resection for fibrosarcoma with reconstruction using polypropylene mesh and a caudal superficial epigastric axial pattern flap: a prospective clinical study of the technique and results in 6 cats

OBJECTIVE

To describe and evaluate a technique for radical resection of the lateral body wall for treatment of fibrosarcoma with reconstruction using polypropylene mesh and a caudal superficial epigastric axial pattern flap in cats.

STUDY DESIGN

Prospective, clinical study.

ANIMALS OR SAMPLE POPULATION

Six client-owned cats with fibrosarcoma.

METHODS

Six cats with histologically confirmed fibrosarcoma of the lateral body wall were staged using radiography and/or computer tomography scanning. Preoperative radiotherapy was used in 3 cats. All cats had the lateral abdominal wall resected and reconstructed with polypropylene mesh. A caudal superficial epigastric flap was mobilized and rotated to close the skin deficit. The animals were evaluated after surgery for wound complications, tumor recurrence, and metastasis. Outcome was assessed by patient examination and client consultation.

RESULTS

Minor dehiscence of the skin flaps occurred in 2 cats, and 1 other cat was successfully resuscitated from respiratory and cardiac arrest after surgery. All tissue specimens were tumor-free at the surgical margins. Follow-up times ranged from 12 to 21 months, with a mean time of 17.2 months. None of the cats had evidence of local tumor recurrence or metastasis; outcome was judged good to excellent in all cats.

CONCLUSIONS AND CLINICAL RELEVANCE

Radical lateral body-wall resection and reconstruction is an effective technique for achieving local tumor control with acceptable patient morbidity. Further studies are needed to assess whether the technique will result in improved tumor-free intervals and survival times.

A lipoma of the extensor tendon sheaths in a horse

This report describes the identification and surgical removal of a lipoma from the extensor tendon sheaths of a horse. To the authors' knowledge, this is the first report of a lipoma of the extensor tendon sheaths of a horse. Ultrasonographic evaluation was crucial to patient management, providing information regarding the soft tissue mass characteristics, tumor margins and synovial involvement prior to surgical exploration. Surgical removal was performed and was curative.

Piloleiomyosarcoma in seven ferrets

In each of seven ferrets (Mustela putorius furo) with leiomyosarcoma, a single dermal mass was identified and biopsied. Each mass consisted of a well-demarcated but nonencapsulated proliferation of large spindle- to strap-shaped cells arranged in interwoven bundles. The cells resembled the smooth muscle cells of the adjacent arrector pili muscles, but with marked nuclear pleomorphism. Immunohistochemical staining for smooth muscle actin, desmin, and vimentin was positive and staining for myoglobin and cytokeratin was negative. Follow-up on three of the ferrets indicates that the prognosis is good following complete surgical excision.

Alveolar rhabdomyosarcoma of the limb in a sheep

Tumor mass was detected in the skeletal musculature of the tibia in a sheep slaughtered at abattoir. Histologically, the tumor cells were in a typical alveolar pattern, and showed a cartilaginous tissue differentiation in some areas of the tumor mass. This tumor examined by avidin-biotin-peroxidase method was found to be positive for myoglobin. The diagnosis of undifferentiated alveolar rhabdomyosarcoma was based on the results of histopathology and immunohistochemistry.

The use of a latissimus dorsi muscle flap for scapular reconstruction in a cat following fibrosarcoma excision

A latissimus dorsi muscle flap was used to reconstruct a proximal scapular defect in a cat after excision of a fibrosarcoma that had recurred after eight surgeries, radiation therapy, and chemotherapy. To obtain appropriate surgical margins, infraspinatus and supraspinatus myectomy and scapular spinous ostectomy were performed. The latissimus dorsi muscle flap was rotated into the defect and anchored to four holes placed in the cranial border of the scapula. The cat showed no lameness at 6, 21, 42, and 147 days after surgery. The latissimus dorsi muscle flap was successful for proximal scapular reconstruction in this cat.

Pleomorphic rhabdomyosarcoma in a cow

In a 5-year-old Holstein cow, a neoplasm composed of a large intramuscular mass and multiple metastases in the lungs and lymph nodes was diagnosed as a pleomorphic rhabdomyosarcoma. This neoplasm was characterized by marked variation in tumor cell size and giant cells with single bizarre nuclei. Although the presence of cross striations and myoglobin could be confirmed, expression of alpha-smooth muscle actin (SMA) was also recognized in a few cells. Neoplastic cells showing intense staining for desmin, vimentin and proliferating cell nuclear antigen irrespective of their size differed from those in an embryonal rhabdomyosarcoma that exhibited a wide spectrum of differentiation, reminiscent of normal skeletal myogenesis. The cellular pleomorphism and SMA expression seemed to be characteristic of deviation from normal muscle cells or satellite cells in adult muscle.

Primary hemangiosarcoma of the iliopsoas muscle eliciting a peripheral neuropathy

An eight-year-old, male castrated bullmastiff presented to the Kansas State University Veterinary Medical Teaching Hospital with left hind-limb paralysis. A mass was identified in the left paralumbar soft tissue adjacent to the fourth (L4) to sixth (L6) lumbar vertebrae by magnetic resonance imaging. The iliopsoas muscle contained the mass which was identified as a hemangiosarcoma on histopathological examination. Hemangiosarcoma is rarely reported as a primary tumor arising from muscle vascular endothelium.

Epitheliotropic T-cell gastrointestinal tract lymphosarcoma with metastases to lung and skeletal muscle in a cat

An Abyssinian cat examined because of hypoproteinemia and weight loss was found to have epitheliotropic T-cell lymphosarcoma of the gastrointestinal tract. Neoplastic lymphocytes infiltrated the epithelium and lamina propria of the stomach, small intestine, and large intestine. Metastatic foci were found in the lungs and the musculature of the right hind limb. Chemotherapy resulted in transient shrinkage of the lung and limb masses; however, these masses grew to approximately their original size within 2 weeks after initiation of treatment, and the cat was euthanatized.

Skeletal muscle lymphoma in a bullmastiff

A 16-month-old, neutered male bullmastiff was presented for acute onset of massive swelling of the right hind limb. Primary skeletal muscle lymphoma was diagnosed based on cytopathology, surgical biopsy, and necropsy findings. Cutaneous metastases developed during the hospitalization, and additional metastases were found in the heart and thoracic wall. Primary skeletal muscle lymphoma is a rare form of lymphoma in dogs and should be considered as a differential diagnosis for acute, soft-tissue swelling of the limb.

Disseminated hemangiosarcoma in the horse: 35 cases

Thirty-five cases of disseminated hemangiosarcoma (21 clinical cases and 14 previously reported cases) were reviewed to describe the disease in horses. Hemangiosarcoma occurred in mature, particularly middle-aged horses, with no apparent sex predilection. Thoroughbreds seemed to be overrepresented (13 cases) but a true breed predilection could not be established. The respiratory and musculoskeletal systems were most commonly affected and presenting complaints included dyspnea (26%), subcutaneous or muscular swelling (24%), epistaxis (17%), and lameness (12%). Heart and respiratory rates were usually increased and mucous membrane color was frequently pale or icteric. Capillary refill time and rectal temperature were often normal. Anemia (88%), neutrophilic leukocytosis (62%), and thrombocytopenia (48%) were common. Examination of tissue samples collected by fine-needle aspirate or biopsy established an antemortem diagnosis in 4 horses. The diagnosis was made during postmortem examination in the remaining 31 horses. The lung and pleura (77%), skeletal muscle (46%), and spleen (43%) were most commonly affected. A primary site of tumor involvement could be identified in 22 horses. Hemangiosarcoma should be included as a differential diagnosis for horses with evidence of hemorrhage into body cavities, skeletal muscle, or subcutaneous locations.

Intramuscular desmoid tumor (musculoaponeurotic fibromatosis) in two horses

Intramuscular desmoid tumors (musculoaponeurotic fibromatosis) were discovered in two young adult horses. The tumor in one horse was in the lateral cervical musculature, and that in the second horse occurred in the pectoral musculature. Histopathologic features were similar in both horses and included proliferation of fibroblasts and cells expressing muscle actin (myofibroblasts), with extensive dissecting fibrosis within muscle. These features are similar to those of desmoid tumors in humans, particularly those also known as musculoaponeurotic fibromatosis. Dissection of these lesions revealed a single central (horse No. 1) or multiple central (horse No. 2) fluid-filled cavities with associated sterile inflammation. The presence of these cavities supports the hypothesis that equine desmoid tumors are traumatic in origin, possibly occurring at sites of injections or bursal rupture. Surgical excision of the tumor in horse No. 1 was apparently curative, but the extent of the tumor in horse No. 2 precluded surgical excision.

Lymphangiosarcomas in cats: a retrospective study of 12 cases

Clinical, macroscopic, and histologic features of 12 lymphangiosarcomas in cats are described. Nine tumors were located in the subcutaneous tissue at the caudoventral abdominal wall (eight cats) or in the neck (one cat). The remaining three cats had lymphangiosarcomas around the cranial mesenteric artery (two cats) or precardial in the mediastinum (one cat). Macroscopically, the tumors were noncircumscribed, white, edematous, and intermixed with fat tissue. Histologic features varied from cleft-forming and cavernous growth to papilliform and solid patterns. Follow-up data were available for seven cats with subcutaneous lymphangiosarcomas. All these cats died or were euthanatized within 6 months after surgery because of poor wound healing, local recurrence, or distant metastases. The cats with abdominal or thoracic masses were either euthanatized at surgery or within 6 months after the first surgery because of recurrent chylothorax, chyloperitoneum, or distant metastases.

Musculoskeletal system neoplasia

Tumors of the musculoskeletal system are rare in horses; however, they must be taken seriously. Diagnosis requires observation of clinical signs, radiographic findings, and histological examination. Veterinarians must realize prognosis is not favorable for most tumors; however, some of these tumors can be treated or at least ameliorated. Tumors discussed in this article include: osteoma and osteosarcoma; osteoblastoma; chondrosarcoma; fibroma and fibrosarcoma; plasma cell myeloma; synovioma; rhabdomyosarcoma and tumors metastatic to the musculoskeletal system.

Infantile desmoid-type fibromatosis in an Akita puppy

A 10-week-old Akita puppy was evaluated for a reported umbilical hernia. Repair of the hernia had been attempted three times prior to referral. A defect in the ventral abdominal wall with an associated soft-tissue mass was identified on abdominal radiographs. Exploratory surgery was performed; the mass was resected and the abdominal wall defect was repaired. Histopathological evaluation of the mass was consistent with infantile desmoid-type fibromatosis.

Metastatic multicentric neurofibrosarcoma of the lumbosacral plexus in a cow

A metastatic multicentric neurofibrosarcoma of the lumbosacral plexus in an adult cow is described. The left lumbosacral plexus was obliterated by a mass which extended through the intervertebral foramen into the spinal canal and between the dorsal arches of the fifth and sixth lumbar vertebrae. A closely associated (possibly contiguous) mass extended into and separated the left sacroiliac joint. Multiple similar masses involved peripheral nerves and skeletal muscles of the pelvis, pelvic limbs, and abdominal wall. Metastatic lesions were scattered throughout the lungs. The lumbosacral lesion and all other masses consisted of interwoven bundles of loosely cohesive, elongated cells separated by variable collagenous matrix. Many neoplastic cells were positive for S-100 protein. Ultrastructurally, fibroblastic cells were mixed with scattered cells possessing schwannian characteristics.

Spontaneous rhabdomyosarcomas in aged Mastomys (Praomys coucha)

Two spontaneous tumours in the hind leg of 2 aged Mastomys were diagnosed as poorly differentiated rhabdomyosarcomas. In both cases, the neoplastic cells had no evidence of cross-striation, but had a positive reaction for muscle-specific proteins. This is the second report of rhabdomyosarcomas in Mastomys, and the first described in detail.