Nasal chondrosarcoma in a Simmental cow

The pathologic features of a nasal chondrosarcoma, a rare tumor of bovines, in a Simmental cow are described. Upon clinical examination, stertor, difficulty in breathing, poor body condition, and a nasal mass were found. Histopathologic examination revealed that the mass was composed mostly of numerous cartilaginous lobules surrounded by spindle-shaped cells, often showing mitotic figures, atypical chondrocytes, and lacunae containing 2 or more cells. On the basis of the histological features, the mass was diagnosed as a nasal chondrosarcoma.     

A mixed apocrine gland tumor with metastases to the bone and bone marrow in a miniature poodle

A 10-year-old female miniature poodle had a mass in its carpal joint of the left forelimb. The tumor was divided into small multiple lobules by delicate connective tissues, and necroses were found in some of the central lobules. In some connective stromal areas, chondroid and osteoid tissues were formed. The tumor cells were similar to the structure of apocrine gland epithelial cells with apical blebs resembling apocrine secretion and eosinophilic secretary materials within the luminal space, and spindle cells were sometimes found in the basal area of the glandular structure. In some areas, tumor cells invaded in the blood vessels, bone and bone marrow. Immunohistochemically, the tumor cells forming tubulo-acinar to solid structures were intensely positive for cytokeratin and keratin K8/K18, and the spindle cells were positive for vimentin and alpha-smooth muscle actin. This case was diagnosed as a malignant mixed apocrine gland tumor with metastases to the bone and bone marrow.     

Intra-abdominal mass aspirate from a cat in heat

A 3-year-old intact female domestic shorthair cat was presented for the evaluation of a palpable intra-abdominal mass in the left caudal abdomen. The cat had a history of anorexia, depression and prolonged estrus over a period of about 1 month. Smears prepared from a fine needle aspirate of the mass revealed large round to oval cells arranged individually or in loose clusters surrounded by pink, fibrillar matrix material. Cytoplasm was basophilic, with many variably-sized vacuoles and variable numbers of small purple granules. The vacuoles within the cells were strongly positive with Oil-Red-O stain. The cytologic features were most suggestive of a neoplasm of epithelial cell origin or inadvertent aspiration of a fatty liver. At laparotomy, the mass was found to involve the left ovary. Histologically, the tumor consisted of dense sheets and nests of irregular polyhedral, pleomorphic cells with abundant, finely vesiculated cytoplasm. The tumor cells were separated into lobules by strands of connective tissue. Based on histologic evaluation, a diagnosis of ovarian luteoma was made. In this report, we document the cytologic and histologic features of an uncommon feline tumor, a luteoma, and address its possible misdiagnosis as hepatic lipidosis when using cytology alone to make a diagnosis.     

Extraskeletal myxoid chondrosarcoma with systemic metastasis in a five-month-old irish setter dog

Extraskeletal myxoid chondrosarcoma was found in a five-month-old male Irish setter dog. At necropsy, the largest mass, measuring 15 × 13 × 13 cm, was found in the right caudal lobe of the lung, and metastatic small masses were observed in multiple organs. Microscopically, the tumor comprised mainly atypical mesenchymal cells and myxoid stroma, which stained positively with Alcian blue. Immunohistochemically, the tumor cells stained positively for vimentin, S-100 protein, neuron-specific enolase, calretinin, and chromogranin A. Ultrastructurally, the cytoplasm of the tumor cells was comprised abundant rough endoplasmic reticulum, mitochondria, Golgi complex, free ribosomes and short irregular microvillous processes extending from the cytoplasm. Based on these pathological findings, this tumor was diagnosed as extraskeletal myxoid chondrosarcoma.     

Primary splenic mesenchymal chondrosarcoma in a dog

A large splenic mass was found during exploratory celiotomy in a 12-year-old Labrador retriever. Histologic examination of the mass revealed a mesenchymal chondrosarcoma. The dog was euthanatized 7 wk postoperatively, due to suspected tumor recurrence. Extraskeletal mesenchymal chondrosarcomas are rare in dogs and are associated with a guarded prognosis.     

IMAGING DIAGNOSIS—SPINAL CORD CHONDROSARCOMA ASSOCIATED WITH SPIROCERCOSIS IN A DOG

A 7‐year‐old neutered female Boerboel cross was examined for progressive left pelvic limb lameness. There was no left patellar reflex but the remaining pelvic limb reflexes were hyperreflexic. Radiographically, there was a poorly mineralized opacity occupying the intervertebral foramen at L4–L5. On computed tomography images there was a hyperattenuating intramedullary lesion at L4–L5 that continued caudally, lateralized to the left and became extramedullary, terminating at L5–L6. In addition, well marginated, hyperattenuating lesions were noted at two muscular sites. The dog underwent euthanasia and a caudal esophageal mass was found at post mortem examination. The tumors in the spinal cord, the esophagus, and the skeletal muscles were diagnosed histologically as low‐grade chondrosarcoma undergoing endochondral ossification. Spirocerca lupi‐induced esophageal chondrosarcoma was believed to be the primary site from which the other, presumably metastatic, lesions originated.     

Hematogenous metastasis of embryonal rhabdomyosarcoma originating from skeletal muscle in a young dog.

An 8-month-old, intact male Golden Retriever with a history of left forelimb lameness for 2 months was presented to the Veterinary Medical Teaching Hospital of Konkuk University (Seoul, Korea). Results of a physical examination revealed a mass in the left axillary region. A thoracic radiography showed an osteolytic lesion in the scapula and the presence of a soft tissue density from the thoracic wall to the scapula. A computerized tomography revealed a mass invading into the scapula, and small nodules in the lung that suggested metastasis. At necropsy, a pale-yellow, irregular, firm, 8 x 10 x 5 cm mass extended from axillary region and destroyed the scapular. In addition, small nodules were noted in the lung. On microscopic examination, the mass consisted of round-to-oval cells, with eccentrically located hyperchromatic nuclei and eosinophilic cytoplasm in fibromyxoid stroma. Tumor cells were observed in blood vessels in the primary mass. Tumor cells strongly expressed vimentin, desmin, and myoglobin. In phosphotungstic acid-hematoxylin staining, cross-striations were detected in rhabdomyoblasts. In periodic acid-Schiff reaction, only a few cells were detected. The diagnosis was primary rhabdomyosarcoma of the appendicular muscle of a young dog. The tumor presumably originated in the skeletal muscle of the limb, invaded into the adjacent scapular bone, and metastasized to the lung.     

Primary chondrosarcoma in the skull of a dog

Chondrosarcoma of the skull is a rare primary malignant tumor that is slow-growing, but locally aggressive. A 5-year-old, golden retriever was presented to our hospital with a swelling in the left side of her head, and the swelling had slowly enlarged over the previous month. There were no significant changes on the neurological examination. A computed tomography scan revealed a large mass involving bone destruction and prominent matrix mineralization. T1-weighted magnetic resonance imaging showed a slightly low-signal intensity area and a T2-weighted image revealed marked, high-signal intensity. There was compression of the adjacent brain parenchyma. Histopathological examination confirmed the lesion to be a chondrosarcoma.     

Chondrosarcoma Associated With the Appendicular Skeleton of 2 Domestic Ferrets

A 5-year-old male neutered ferret (Mustela putorius) and a 2-year-old male neutered ferret were evaluated for fast growing immobile swellings involving the left hock and the right scapula, respectively. In both cases, serum chemistry was unremarkable and a complete blood count demonstrated mild anemia. In case 1, radiographic evaluation demonstrated increased soft tissue density in the region of the distal tibia and fibular tarsal bone. A fine-needle aspirate demonstrated atypical mesenchymal cells, and an incisional biopsy revealed irregular partly mineralized proliferations of cartilage consistent with chondrosarcoma. Computed tomography was performed, demonstrating attachment of the mass to the distolateral tibial epiphysis. A limb-sparing surgery was performed; however, 5 months following resection local reoccurrence was noted. At 18 months, the ferret underwent a left hind limb amputation. No sign of metastatic disease was reported at 27 months. In case 2, radiographic evaluation demonstrated a poorly organized mineralized soft tissue mass extending from the right acromion to the area surrounding the neck of the scapula. Microscopic evaluation of an incisional biopsy revealed a chondrosarcoma. A forequarter amputation was performed. The ferret died 4 years later with no evidence of local recurrence or the development of metastatic disease. These 2 cases represent the first reports of chondrosarcoma in the appendicular skeleton of 2 ferrets. Based on these 2 cases, local recurrence may be expected unless adequate surgical margins are achieved. The metastatic potential of chondrosarcoma in this species appears to be low.     

Primary chondrosarcoma in the liver of a dog

Primary chondrosarcoma was found in the quadrate lobe of the liver of a 6-year-old, intact, male Golden Retriever. At 6 months after partial hepatectomy, recurrence in the liver occurred. The dog died of its systemic metastases 10 months thereafter. Histologically, the hepatic mass revealed neoplastic chondrocytes with abundant chondroid matrix, and there were few myxoid areas where the cellularity and pleomorphism of the neoplastic cells were more prominent. The neoplastic cells were positive for periodic acid-Schiff and were immunohistochemically positive for vimentin and S-100 protein; the matrix was deeply stained for alcian blue and was metachromatic for toluidine blue stain. This tumor might be derived from pluripotent mesenchymal cells in the connective tissue of the liver. To the best of our knowledge, in all mammalians, including humans, this is the first report of extraskeletal chondrosarcoma primarily arising in the liver.     

Thyroid c-cell carcinoma in an African pygmy hedgehog (Atelerix albiventris).

A 3-yr-old African pygmy hedgehog (Atelerix albiventris) was submitted with dysphagia, weight loss, and tetraparesis. A palpable mass was found on the ventral neck. Histologic examination revealed replacement of the thyroid gland by a highly cellular, expansile, and infiltrative mass composed of lobules of polygonal cells separated by fine fibrovascular septa. Examination of ultrathin sections revealed tumor cells with few to many dense-core neuroendocrine granules, approximately 100-200 nm in diameter, and stromal amyloid. Immunohistochemical stains were positive for neuron-specific enolase. Only rare cells had positive immunohistochemical staining for calcitonin. Findings are consistent with a neuroendocrine tumor of C-cell origin. This is the first report of a C-cell carcinoma in a hedgehog.     

COCCYGEAL VERTEBRAL CHONDROSARCOMA IN A SAINT BERNARD DOG: A CASE REPORT

A 6-year-old male Saint Bernard dog was examined because of a firm nonpainful tail-base mass. Radiographs revealed an expansile heterogeneous bony mass of the sixth coccygeal vertebra. The tail was amputated. The histologic diagnosis was coccygeal vertebral chondrosarcoma. Chondrosarcomas account for ten to eleven percent of all skeletal tumors and occur commonly in the flat bones in large-breed dogs. Radiographically chondrosarcomas appear predominantly osteolytic but may contain mottled mineralized densities. In the dog described here the radiographic signs were typical of a malignant cartilaginous tumor: cortical destruction, mottled mineralized densities, ill-defined margins, and continued but relatively slow growth. However, there was no periosteal reaction and the chondrosarcoma was at an unusual site.     

Metastatic osteosarcoma tumor thrombus in a Cavalier King Charles Spaniel presenting with dyspnea

A six-year-seven-month-old female neutered Cavalier King Charles Spaniel was referred for the investigation of progressive dyspnea and hyphema in the right eye with secondary glaucoma. Previous medical history included a high-grade soft tissue spindle cell sarcoma removed from the cranial sternal region one year before.On presentation at the referral hospital, the dog was tachypneic and dyspneic. The heart rhythm was regular and there was a soft left-sided systolic murmur. Echocardiography identified the presence of a mass significantly occluding left heart inflow, with no other lesions identified. Thoracic radiographs documented a localized alveolar pattern within the left caudal lung lobe. The size of the heart and pulmonary vessels were within normal limits, indicating a non-cardiogenic alveolar pattern.Given the clinical presentation of dyspnea and high index of suspicion of intra-cardiac neoplasia, the dog was considered to have a grave prognosis and therefore euthanized. Post-mortem gross and histopathologic examination revealed the presence of a metastatic osteosarcoma tumor thrombus in the left atrium and pulmonary vein, metastatic osteosarcoma infiltrating the myocardium, lungs, the uveal tract of the right eye, and both adrenal glands. Whitney grade II myxomatous changes were noted on the mitral and tricuspid valve leaflets.This report describes an unusual intra-cardiac tumor thrombus in a dog presenting with dyspnea. Cavalier King Charles Spaniels presenting with dyspnea often raise suspicion for myxomatous mitral valve disease. However, as demonstrated in this case, other more unusual causes of dyspnea should also be considered in the absence of classic clinical findings.     

Benign peripheral nerve sheath tumor of the perianal region in a young pony.

A 20 x 10 cm, lobulated mass was present in the perianal region of a 4-year-old Dales pony. Histopathology revealed an unencapsulated, loose arrangement of sheets and whorls of narrow mesenchymal cells, situated in the deep dermis. Intervening areas had a myxomatous appearance. The whorls were often arranged around a central structure resembling an axon or a vascular structure. Immunohistochemistry revealed that the elongated mesenchymal cells and central axon-like structures expressed vimentin, S-100, and neuron-specific enolase, but not pancytokeratin, glial fibrillary acid protein, and the neurofilament markers, NR4 and 2F11. On the basis of the histopathology and immunohistochemistry, a diagnosis of benign peripheral nerve sheath tumor (schwannoma type) was made. This case was unusual in that the concentric laminations of Schwann cells were very loosely arranged, with an intervening myxomatous stroma (Antoni type B appearance) and despite its benign histological appearance, the mass extended deeply to the proximal sacral vertebrae. Its exact origin was unclear; it may have arisen from cutaneous nerves with deep extension or from neural structures in the sacral region. Due to the incomplete surgical removal, regrowth of the mass occurred.     

A subcutaneous mass on the neck of a horse

A 25-year-old Arabian gelding was presented for investigation of a subcutaneous neck mass. Fine-needle aspirates and impression smears revealed mast cells with widely varying degrees of cytoplasmic granulation and scattered eosinophils. Histopathology revealed a poorly circumscribed mass composed of sheets and bundles of mast cells with a large population of eosinophils. The mast cells were separated into numerous lobules by a heavy collagenous stroma, and multifocal collagen necrosis was present. Strong reactivity of the tumor cells for both Giemsa and toluidine blue stains confirmed the diagnosis of a mast cell tumor, and a Luna stain accentuated the eosinophilic infiltrates. Cutaneous mast cell tumors are found in many domestic animals but are uncommonly encountered in horses. Equine cutaneous mast cell tumors are usually benign, and there are no reports of visceral metastasis. Surgical excision is thought to be curative.     

Squamous cell carcinoma in a digit of the hind limb with systemic metastasis in a 17-year-old female koala

We encountered a case of cutaneous squamous cell carcinoma (SCC) in a 17-year-old female koala at a zoo. A fragile, papillary, elevated mass was found on the third digit of the right hind limb. SCC was identified histopathologically: squamous cell-like polygonal tumor cells showed a nest-like growth pattern with epidermal down growth, central keratinization and necrotic foci, and invaded dermal connective tissues. Metastatic lesions were observed in various organs, including the lung and axillary lymph node: in the lung, multiple metastatic foci similar to the primary lesion, and in the axillary lymph node, individual polygonal tumor cells infiltrated the sinusoids. Immunohistochemistry revealed that the tumor cells were positive for proliferating cell nuclear antigen, which exhibited 32–33% of labeling indices in the tumor cells. To our knowledge, this is the first report of a case of SCC in a digit of a koala.     

Suture exostosis with concurrent nasal septum chondrosarcoma in a horse

A 15‐year‐old Hanoverian mare presented with a 10‐day history of facial swelling in the right maxillary and frontal regions, left epiphora and intermittent right epistaxis. Radiographs revealed suture exostosis of both nasofrontal sutures and a deviated and thickened nasal septum. Computed tomography (CT) of the skull revealed exostosis of the nasolacrimal sutures and ducts bilaterally of both nasofrontal sutures and of the right zygomatocomaxillary and lacrimomaxillary sutures. The mid‐to‐caudal aspect of the nasal septum was thickened and had multiple well demarcated hypoattenuated regions within the septum. Histological examination of biopsies taken from the right nasofrontal suture and the nasal septal mass revealed suture exostosis and nasal septum chondrosarcoma. The horse was treated with rest and anti‐inflammatories. The facial swelling and left epiphora were improved at 7 months telephone follow‐up. This report is the first to describe a nasal septum chondrosarcoma in a horse. Additionally, we suggest that the suture exostosis may have developed due to an alteration of the biomechanics of the skull sutures secondary to the septal tumour.     

A PROTRACTED CASE OF CRYPTOCOCCAL NASAL GRANULOMA IN A STALLION

SUMMARY A 13-year-old Standardbred stallion presented with a unilateral mucopurulent nasal discharge and airway obstruction was found to have an extensive cryptococcal nasal granuloma. Treatment was not attempted. The stallion was destroyed 26 months later having completed 2 successful breeding seasons. The granuloma had gradually increased in size and almost completely occupied the left nasal cavity and paranasal sinuses. It was characterised histologically by fibrous and myxomatous tissue and masses of yeasts. A cryptococcal granuloma found within the wall of the jejunum could represent evidence of dissemination, and organisms were seen within alveoli, bronchioles and the intestinal lumen.     

Successful management of an arytenoid chondrosarcoma in a dog

An eight‐year‐old Doberman pinscher was presented with a four‐week history of inspiratory stridor, dysphonia, inappetence and weight loss. Inspiratory stridor was apparent and became more pronounced during gentle compression of the larynx. Previous investigations, including laryngoscopy, had revealed the presence of a left‐sided arytenoid mass. Histological examination of pinch biopsies was not diagnostic. The mass was removed by resection of the arytenoid cartilage through a ventral laryngotomy allowing salvage of the cuneiform process. Histological examination of the laryngeal mass was consistent with a chondrosarcoma, grade I, infiltrating the arytenoid cartilage. Re‐examination at 12 months showed complete resolution of the clinical signs and no signs of metastatic disease. To the authors’ knowledge this is the first report of successful surgical intervention for laryngeal chondrosarcoma. This case demonstrates that resection via a ventral laryngotomy may be a viable and curative therapeutic option for some sarcomas of the larynx.     

Mammary adenocarcinoma in a male squirrel monkey (Saimiri sciureus)

A nodule was identified within the right mammary gland of a 16-year-old male squirrel monkey (Saimiri sciureus). The mass was excised and diagnosed as a mammary adenocarcinoma. The monkey developed congestive heart failure 1.5 years later and was euthanatized. At necropsy, a subcutaneous mass was found in the right axillary region. Histologically, the mass was identified as a lymph node whose architecture was effaced by neoplastic cells resembling those of the mammary tumor. Metastasis to internal organs was not observed. This is the first reported case of a mammary tumor in a New World primate and the only known case of mammary cancer in a male nonhuman primate.