Feline inductive odontogenic tumour in a Burmese cat

A 7-month-old, male, Burmese cat was presented with an oral mass that had rapidly regrown following excisional biopsy 3 weeks earlier. The tumour was identified by histological examination as a feline inductive odontogenic tumour. A unilateral segmental mandibulectomy was performed. Although dental malocclusion resulted from mandibular drift to the operated side, the cat displayed minimal dysphagia post-operatively and there was no evidence of tumour regrowth 8 months after surgery. Feline inductive odontogenic tumour is a rare dental tumour described exclusively in cats under 3-years-of-age. Although histopathologically benign, feline inductive odontogenic tumour grows by expansion and can infiltrate underlying bone to cause considerable local destruction. This article is intended to increase awareness of this unusual tumour which, with complete surgical excision, carries a good prognosis. It also emphasises the importance of obtaining a histological diagnosis from oral mass lesions to direct appropriate therapy and to provide an accurate prognosis.     

Radioactive gold-198 seeds for the treatment of squamous cell carcinoma in the eyelid of a cat

A 19-year-old, speyed, domestic short-hair cat was presented with an eyelid tumour of 3 months duration. Ophthalmic examination revealed a large, raised, ulcerated and bleeding mass affecting the left lower eyelid. The mass was 12 mm x 10 mm in size, extended to the medial canthus and had eroded 10 mm of eyelid margin. Mandibular lymph nodes were not palpably enlarged. A diagnosis of squamous cell carcinoma was confirmed by histologic examination. Due to involvement of more than half the lower eyelid, it was decided that treatment with radioactive gold-198 seeds was appropriate. Nine radioactive gold-198 seeds were implanted, delivering a minimum tumour dose of 65 Gy. Three weeks postoperatively the mass had resolved, with only a small scab remaining. After a further 3 weeks, there was no evidence of the eyelid tumour. Although approximately 7 mm of eyelid margin was absent, this did not cause any clinical signs other than mild conjunctivitis. There was no evidence of the tumour 10 months postoperatively, when the cat was euthanased for unrelated disease.     

A case of feline primary inflammatory mammary carcinoma: clinicopathological and immunohistochemical findings

The clinicopathological and immunohistochemical findings of a primary feline mammary tumour with features similar to human and canine primary inflammatory carcinoma are described for the first time. The cat presented to the clinic for the rapid onset of oedema, severe erythema, local pain and warmth of the inguinal region, with a pustular-to-nodular cutaneous lesion in association with an ill-defined underlying mass. An epithelial malignant tumour was diagnosed by cytological investigation. Necropsy revealed a thickening of the skin with oedema of the subcutis in the right inguinal area, and regional and distant metastases. Histology showed an unencapsulated tubulopapillary proliferation of malignant epithelial cells, with a massive embolisation in the dermal lymphatics and a mild inflammatory infiltrate. Through immunohistochemistry, the tumour was found to be oestrogen (ER)-alpha-, androgen (AR)- and progesterone (PR)-negative; neoplastic cells were ER-alpha, AR-negative and focally PR-positive. An irregular, mild and focal HER-2 immunoreactivity was present (score +1, non-HER-2 overexpressing). The neoplastic cells were cyclo-oxygenase-2 and vascular endothelial growth factor positive.     

Chondrosarcoma of the proximal humerus in a cat

Chondrosarcoma of the proximal humerus was diagnosed in a four-year-old, castrated male, domestic shorthair cat that was presented with a slowly growing solid mass in the region of the proximal humerus. Forequarter amputation was advised, but declined by the owners. Following surgical debulking clinical signs resolved, but two months after surgery the cat was readmitted because the mass had recurred in the same region. The forequarter was amputated. Histopathological evaluation of the tumour confirmed the diagnosis of chondrosarcoma. Follow-up examinations performed over a period of 15 months from initial presentation revealed that the cat was doing well and had no signs of metastatic disease. To the authors' knowledge, this is the first reported case of chondrosarcoma of the proximal humerus in a cat to be diagnosed and surgically treated. This case demonstrates that animals with such tumours may recover well after complete excision.     

Cutaneous haemangiosarcoma of the lower eyelid in an elderly white cat

A case of cutaneous haemangiosarcoma of the left lower eyelid in a 15-year-old white domestic shorthair cat is reported. A protuberant red mass occupying one-third of the lower eyelid margin length was present. Intermittent haemorrhage occurred from the mass surface. Surgical biopsy had revealed a locally invasive tumour composed of numerous irregular blood-filled spaces lined by a single layer of plump endothelial cells and separated by thin fibrous septa. Mitotic activity was rare and the appearance was consistent with a low-grade haemangiosarcoma. The mass continued to enlarge and referral was sought. Due to financial constraints and the owner's wish for a single procedure, enucleation with an axial pattern flap based on the superficial temporal artery was undertaken. Histopathology of the excised tissue confirmed the presence of a well-differentiated haemangiosarcoma. Tumour-free excisional margins were confirmed, the surgical area healed uneventfully, and there has been no recurrence during the subsequent 16 months.     

Darier's sign associated with a cutaneous mast cell tumour in a cat with multiple neoplasms

A cutaneous mast cell tumour associated with Darier's sign in a cat with multiple neoplasms is described. A 14-year-old cat with multiple neoplasms, one of which was a mast cell tumour developed marked subcutaneous oedema and erythema following palpation. The phenomenon is similar to Darier's sign described in people with mast cell tumours. The pathology of the Darier's sign is discussed.     

Cryohypophysectomy used in the treatment of a case of feline acromegaly

A 10-year-old female spayed cat was diagnosed with acromegaly secondary to a pituitary tumour. At the time of diagnosis, the cat had insulin-resistant diabetes mellitus and its insulin-like growth factor-I levels were elevated. Clinical signs included polyuria, polydipsia and weight gain. Persistent hyperglycaemia and glucosuria were identified, and fructosamine levels remained elevated. Magnetic resonance imaging of the brain showed a pituitary tumour. Transsphenoidal cryohypophysectomy was used to treat the pituitary tumour. Postoperatively, the serum insulin-like growth factor-I levels decreased and the diabetes mellitus was controlled with routine levels of insulin. To the authors' knowledge, this is the second reported case of acromegaly treated with cryohypophysectomy, and the first that reports a favourable long-term outcome. Cryohypophysectomy may be a safe and effective treatment for cats with a pituitary mass resulting in acromegaly.     

Rectal prolapse of an ileocaecal neoplasm associated with intussusception in a cat

Intussusception associated with lymphoma of the ileocaecocolic junction was diagnosed in a 12-year-old female domestic short-haired cat that presented with a 3-week history of diarrhoea and a protruding anal mass. Surgical exploration revealed an ileocolonic intussusception proximal to the mass at the ileocaecal junction which was excised. A diagnosis of ileocaecocolic lymphosarcoma was made and euthanasia was later performed. This is an unusual case of an ileocaecal junction tumour that manifested as a rectal prolapse associated with intussusception in a cat.     

Feline cutaneous neuroendocrine carcinoma (Merkel cell tumour): clinical and pathological findings

A case of a feline Merkel cell tumour is described. An 8-year-old, female cat developed a round, alopecic, reddish mass on the nose. Wide excisional surgery was performed with cartilage resection. Histologically the mass was composed of solid islands of mostly basophilic densely packed cells with a scant cytoplasm, which was suggestive of a neuroendocrine origin. Results of immunohistochemical studies using antibodies against neurone-specific enolase, chromogranin, synaptophysin and pan-cytokeratin allowed classification of the lesion as a Merkel cell tumour. Ultrastructurally, dense core granules were identified in the cytoplasm. In a 2-year follow-up no relapses or metastases were observed. The clinical course recorded is in contrast with the malignant nature of a Merkel cell tumour recently described in a cat and of the human Merkel cell tumour, but is similar to the course of the canine Merkel cell tumour which is often benign. Early diagnosis along with the use of wide surgical excision might be considered an important factor in preventing relapse of this tumour.     

Anal sac adenocarcinoma in a Siamese cat

A 12-year-old male neutered Siamese cat presented with a history of inappetance and lethargy and an enlarged left anal sac. The anal sac was surgically excised and histopathology confirmed the diagnosis of anal sac adenocarcinoma. Perianal tumours are rare in the cat and anal sac adenocarcinoma has not been previously reported. This is in contrast to the dog where anal sac adenocarcinoma is a well recognised albeit uncommon tumour.     

Microchip-associated fibrosarcoma in a cat

A 9-year-old, neutered male cat was presented for a subcutaneous mass on the neck. After surgical removal of the mass, a pet identification microchip was found within the tumour. Histological examination of the mass revealed typical features of the feline postinjection sarcoma. The cat had never received injections at the tumour site; all routine vaccinations were administered in the hindlimbs. Few cases of sarcomas developing at the site of microchip application have been reported in animals, although the contributory role of vaccine administrations has not been ruled out. This is the first report of a microchip-associated fibrosarcoma in a cat. Adherence to American Association of Feline Practitioners vaccination guidelines, avoiding the interscapular area, enabled confirmation of the definitive aetiology of the neoplasia.     

Metastatic synovial cell sarcoma in two cats

Synovial cell sarcoma (SCS) with metastasis to the regional lymph node was diagnosed in two cats. Synovial cell sarcomas are rare in cats and metastatic SCS has not previously been reported. In both cases, treatment consisted of limb amputation and adjuvant doxorubicin. Local tumour recurrence and pulmonary metastases were diagnosed in one cat 316 days postoperatively. This cat died of chronic renal failure 444 days after limb amputation. The second cat died of an acute pulmonary thromboembolism 41 days postoperatively without evidence of local tumour recurrence or metastatic disease.     

Intrathoracic lipoma in a cat

A 10 yr old female cat presented for an acute onset of back arching, regurgitation, and open mouth breathing. Radiographs indicated the presence of a large intrathoracic mass. Computed tomography confirmed the presence of a large mass of fatty density in the dorso-caudal mediastinum. The mass was removed via right intercostal thoracotomy, and histopathology confirmed the mass as a lipoma. The cat was continuing to recover well as of 21 mo after surgery. This is the first reported case of an intrathoracic lipoma in a cat.     

Surgical management of a recurrent spinal meningioma in a cat

A 13-year-old male neutered Persian crossbred cat was evaluated for hindlimb paresis, ataxia and urinary incontinence that had been progressing over the previous 3 months. Neurologically, the cat had thoracolumbar spinal cord deficits and a myelogram detected the presence of a mass compressing the thoracic spinal cord. A hemilaminectomy was performed to excise the soft tissue mass, subsequently identified histologically as a psammomatous meningioma. The cat regained ambulatory function and continence following surgery until a recurrence of paresis and ataxia 36 months later. A second myelogram suggested local recurrence of the tumour, which was confirmed by histological examination of the tumour after its removal at a second laminectomy. The cat again regained normal neurological function, until a further recurrence 16 months after the second surgery. The meningioma was surgically debulked a third time and the cat regained ambulation and continence postoperatively. This case demonstrates the successful use of repeated surgical resection in the management of a recurrent spinal meningioma in a cat. The cat was ambulatory and continent at a follow-up examination 63 months after the initial presentation.     

Atypical thymoma in a horse: Diagnostic approach and application of an alternative histological classification system

Thymoma is a rare condition in horses. This case of a 24-year-old Warmblood gelding that was presented with oedema and signs of vascular congestion of the left forelimb caused by a thoracic mass is described. The diagnostic work-up included blood chemistry, cytology of pleural effusion, ultrasonography, radiography and the visualisation and collection of a tissue sample by thoracoscopy. Finally, post-mortem findings and histopathology revealed thymic epithelial neoplasia with histomorphologic features previously unreported in horses. The unique mixture of spindle-shaped and epithelioid tumour cells in combination with clear features of malignancy suggested the application of the Moran and Suster histological classification system for thymomas in humans (Moran and Suster, 2008, Curr. Treat. Options Oncol., 9, 288), which has not been reported in an equine case before and fits well to the present case.     

Central hemimaxillectomy and reconstruction using a superficial temporal artery axial pattern flap in a domestic short hair cat

A 2-year-old, neutered male domestic short hair cat presented with a large mass involving the right upper lip and underlying gingiva. A previous attempt at mass excision had failed, and the histopathological diagnosis was reported to be a fibrosarcoma. The cat was otherwise in good health.A central hemimaxillectomy was performed with extensive soft-tissue dissection and maxillofacial reconstruction achieved using an axial pattern flap based on the superficial temporal artery. This is the first reported clinical case of the use of the superficial temporal artery axial pattern flap in the cat. Histopathology identified a periodontal fibromatous epulis.     

Cutaneous T-cell-rich B-cell lymphoma in a horse

Cutaneous malignant lymphomas are rare in horses and comprise predominantly T-cell-rich B-cell lymphomas. They are characterized by multiple tumour nodules affecting predominantly female horses with a survival rate of months to years. At the final stage, metastases to regional lymph nodes occur, whereas widespread organ involvement is rarely reported. In this case report, a cutaneous T-cell-rich B-cell lymphoma in a 7-year-old standardbred gelding with metastases is described. Clinically, multiple cutaneous and subcutaneous nodules, enlarged superficial lymph nodes, rapid weight loss, and ventral oedema were observed. In addition to the clinical findings, necropsy revealed tumour infiltration in multiple body lymph nodes, a solitary pleural mass, and few pulmonary and intestinal tumour nodules. Microscopically, all neoplasms were composed of a densely packed cell population consisting of large lymphoblastic cells expressing CD79a, and numerous small, round, CD3-positive T lymphocytes. With respect to these findings the diagnosis of a cutaneous T-cell-rich B-cell lymphoma with metastases was made.     

Successful treatment of pulmonary aspergillosis in a cat

A 7-year-old, spayed female Domestic Longhair cat was evaluated for a 6-week history of coughing. Thoracic radiography revealed a pleural effusion. Thoracic ultrasound revealed a pleural effusion and a focal lung mass. The cat underwent exploratory thoracotomy and a total left pneumonectomy was performed. Histopathology and cultures revealed fungal pneumonia and pyothorax caused by Aspergillus fumigatus. Abdominal ultrasound, repeat thoracic radiography, urinalysis with culture, and retroviral screening failed to detect evidence of systemic disease. The cat's poorly regulated diabetes mellitus is suspected to be the predisposing factor allowing a fungal pulmonary infection to become established. At 18 months after surgery the cat was still disease-free. To our knowledge this is the first reported case of successful treatment of pulmonary aspergillosis in the cat.     

Intraocular extramedullary plasmacytoma in a cat

An 8-year-old, castrated male Domestic Short-haired cat was referred for evaluation of a possible intraocular neoplasm following previous ocular trauma. The eye was blind, and uveitis and an iridal mass were noted on examination. An enucleation was performed and the mandibular lymph node excised. Histopathologic examination revealed neoplastic proliferation of plasma cells in the iris and lymph node. No other evidence of disseminated disease was detected. This is the first case reported of an intraocular extramedullary plasmacytoma in the cat. The variation in clinical manifestations and potential association with multiple myeloma are not known at this time. Disseminated metastasis from a primary plasmacytoma of the uveal tract could also involve the bone marrow and be indistinguishable from multiple myeloma. Early enucleation, as in trauma-associated sarcomas, may be indicated to prevent metastasis. Periodic systemic evaluation for evidence of multiple myeloma should be performed.     

Extraskeletal osteoma in a cat

This paper describes a case of a benign osseous lesion which arose in the right front leg of an 8-year-old spayed female cat. The growth was situated in the dermal tissue above the olecranon, but not attached to it, and shelled out easily at surgery.
While certain non-neoplastic lesions, such as hamartomas or cases of heterotopic ossification, may appear histologically similar, the present case was considered to be a true tumour on the basis of the clinical, macroscopic and histological findings, and was termed an osteoma. The cat is remaining under observation, but there had been no recurrence 3½ months after surgery.