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A Rock Alpine doe (Capra aegagrus hircus) was presented to the Colorado State University Veterinary Teaching Hospital because of scaling and ulceration over the withers, coronary bands, and dewclaws. The doe was euthanized because of poor prognosis associated with a radiographically identified cranial mediastinal mass, increased respiratory effort, and discomfort. Autopsy revealed a cranial mediastinal mass, and scaling-to-ulcerative lesions affecting the dorsum, ventrum, pinna, neck, teats, coronary bands, and dewclaws. Histologically, the mediastinal mass was an epithelial neoplasm with admixed non-neoplastic T lymphocytes, consistent with a lymphoepithelial (mixed) thymoma. Sections of affected skin were characterized by hyperkeratotic cell-rich interface dermatitis with transepidermal and follicular apoptosis. Thymoma-associated exfoliative dermatitis has been recognized in cats and a rabbit, but has not been reported previously in a goat, to our knowledge. Given that thymomas are not uncommon in goats, thymoma-associated exfoliative dermatitis should be considered a clinical differential in goats with dermatologic disease.

Assuntos

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Background: Thymomas are epithelial neoplasms of the thymus, although lymphocyte infiltration is common. Histological features are not sufficient to define its biological behaviour, which is dependent of clinical criteria of invasiveness and resectability. Myasthenia gravis may happen as a paraneoplastic syndrome in up to 47% of canine thymomas. This article aims at reporting a case of thymoma associated with myasthenia gravis in a dog, emphasizing the morphological, phenotypical and therapeutical aspects.Case: A 7-year-old, male Labrador, was presented with a history of acute dyspnea and exercise intolerance. The physical examination revealed a “red-brick” mucousa, tachycardia and cardiac and pulmonar hypofonese. Chest radiographs revealed an area of increased radiopacity in the cranial mediastinum without a plane of separation to the heart. The eccodopplercardiogram exam identified a poorly delimited mass adjacent to the base of the heart, measuring 9.5x6.8cm. Computed tomography demonstrated it as an expansive neoformation (9.5x6.5x7.8cm). Mass was removed through intercostal thoracotomy and the removed tissue was submitted to histopathology with a diagnosis compatible with type AB thymoma (mixed). Immunohistochemistry was positive for AE1/AE3 citokeratin in 90% of epithelial cells, confirming tumour origin. Tumour infiltrating lymphocytes were positive for CD79a (70%) and CD3 (20%). The proliferation index (Ki-67 imunolabeling) was 60%. About 45 days after surgery the patient was presented with generalized muscle weakness and regurgitation, with confirmed megaesophagus on chest X-ray. Treatment with pyridostigmine was initiated because of suspected myasthenia gravis, and complete remission of the neurological signs occurred within a month. A chemotherapeutic protocol with carboplatin was then instituted. After four sessions, a new thoracic radiograph revealed tumour recurrence in the cranial mediastinum.[...]

Assuntos

RESUMO

Background: Thymomas are epithelial neoplasms of the thymus, although lymphocyte infiltration is common. Histological features are not sufficient to define its biological behaviour, which is dependent of clinical criteria of invasiveness and resectability. Myasthenia gravis may happen as a paraneoplastic syndrome in up to 47% of canine thymomas. This article aims at reporting a case of thymoma associated with myasthenia gravis in a dog, emphasizing the morphological, phenotypical and therapeutical aspects.Case: A 7-year-old, male Labrador, was presented with a history of acute dyspnea and exercise intolerance. The physical examination revealed a “red-brick” mucousa, tachycardia and cardiac and pulmonar hypofonese. Chest radiographs revealed an area of increased radiopacity in the cranial mediastinum without a plane of separation to the heart. The eccodopplercardiogram exam identified a poorly delimited mass adjacent to the base of the heart, measuring 9.5x6.8cm. Computed tomography demonstrated it as an expansive neoformation (9.5x6.5x7.8cm). Mass was removed through intercostal thoracotomy and the removed tissue was submitted to histopathology with a diagnosis compatible with type AB thymoma (mixed). Immunohistochemistry was positive for AE1/AE3 citokeratin in 90% of epithelial cells, confirming tumour origin. Tumour infiltrating lymphocytes were positive for CD79a (70%) and CD3 (20%). The proliferation index (Ki-67 imunolabeling) was 60%. About 45 days after surgery the patient was presented with generalized muscle weakness and regurgitation, with confirmed megaesophagus on chest X-ray. Treatment with pyridostigmine was initiated because of suspected myasthenia gravis, and complete remission of the neurological signs occurred within a month. A chemotherapeutic protocol with carboplatin was then instituted. After four sessions, a new thoracic radiograph revealed tumour recurrence in the cranial mediastinum.[...](AU)

Assuntos

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Thymomas are uncommon neoplasms that are typically located in the cranioventral mediastinum in domestic species, which generally affects older animals. Medical records and sonograms of 50 animals diagnosed with either mediastinal thymoma (n = 35) or lymphoma (n = 15) between January 2005 and February 2012 were reviewed. Cases with definitive cytological and/or histological diagnoses of either thymoma or lymphoma were included in this study. Masses were characterized by echogenicity, presence or absence of cysts, shape, margination, vascularity, and presence of effusion. Many thymomas (57.1%) were sonographically cystic in appearance and nearly all were heterogeneous (94%) in echogenicity compared with lymphoma (P = .0028). Lymphomatous lymph nodes were more likely to be solid (80%) and were equally divided between hypoechoic (47%) and heterogeneous (53%) echogenicities. Sonographic findings of either internal cysts or a heterogeneous echogenicity in mediastinal masses may be suggestive of a thymoma.

Assuntos

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A 7-year-old, castrated male, domestic shorthair cat presented with generalized exfoliative dermatitis, lethargy, anorexia and weight loss. Multiple skin scrapings taken at the time did not reveal any abnormalities. Skin histopathological examination was consistent with sebaceous adenitis or exfoliative dermatitis caused by an underlying thymoma (thymoma-associated feline exfoliative dermatitis). Thoracic radiographs revealed a cranial mediastinal mass, which was removed surgically. Histopathological examinations indicated that it was a thymoma. Within 90 days of surgery, the cutaneous signs had resolved, suggesting a causal relationship between the thymoma and the skin disease. Recurrence of thymoma was detected 24 months after surgery.

Assuntos

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A neoplastic mass measuring 25 x 8 x 3 cm was found in the mediastinum of a 10-year-old Holstein cow. The neoplasm was encapsulated, multilobulated, and cystic. Several firm adhesions were present between the neoplasm and the right cranial lung lobe and the ipsilateral side of the pericardial sac. Under microscopic examination, the neoplasm was characterized by solid sheets of spindle epithelial cells (pancytokeratin and high molecular weight cytokeratin positive) subdivided by fibrous trabeculae. Numerous individualized or small aggregates of mature T-cell (CD3 positive) lymphocytes were scattered throughout the neoplastic cell population. Based on the gross, histologic, and immunohistochemical findings, the neoplasm was diagnosed as a mixed thymoma.

Assuntos

Assuntos