Myasthenia gravis associated with cutaneous lymphoma in a dog

A middle-aged golden retriever presenting with exercise intolerance and multifocal cutaneous nodules was diagnosed as having non-epitheliotropic cutaneous lymphoma with concurrent myasthenia gravis. Treatment with corticosteroids induced short-term remission of the lymphoma and alleviation of myasthenic signs.     

Cervical thymoma originating in ectopic thymic tissue in a cat

Abstract: An 11‐year‐old female spayed domestic shorthair cat was referred to The Ohio State University Veterinary Teaching Hospital (OSU‐VTH) for evaluation of a 6 × 4 × 3.5 cm mass in the left midcervical region causing increased respiratory sounds and lateral deviation of the trachea. A fine needle aspirate of the mass was obtained before referral and the cytology results were compatible with a reactive lymph node. Immunocytochemistry showed increased numbers of CD3+ T lymphocytes and small numbers of CD20+ and CD79a+ medium to large lymphocytes. Differential diagnoses from the referral pathologist were T‐cell‐rich B‐cell lymphoma and feline Hodgkin's‐like lymphoma. A subsequent fine needle aspirate performed at the OSU‐VTH showed similar results. On flow cytometry the majority of cells were CD3+ T lymphocytes that were double positive for CD4 and CD8 (73%), compatible with either a double‐positive (CD4+CD8+) T‐cell lymphoma or lymphocytes from ectopic thymic tissue. The mass was surgically removed. Histopathology and immunohistochemistry of the mass revealed a predominant population of CD3+ small lymphocytes and small numbers of medium to large lymphocytes with moderate anisocytosis and anysokaryosis. A population of cytokeratin‐positive epithelial cells surrounded small microcystic structures filled with eosinophilic material and structures interpreted as Hassall's corpuscles. These findings were consistent with thymic tissue and a diagnosis of ectopic thymoma was made. PCR results for lymphocyte antigen receptor rearrangement (PARR) were negative. The cat had no evidence of disease 16 months after removal of the mass. To our knowledge this is the first report of an ectopic cervical thymoma in a cat. The clinical and diagnostic features of this unusual case will be useful in helping veterinarians and pathologists obtain a presurgical diagnosis and establish a prognosis for similar lesions.     

Acquired myasthenia gravis associated with a non-invasive thymic carcinoma in a dog

An 8 1/2-year-old neutered male Beagle was diagnosed with acquired myasthenia gravis associated with a non-invasive thymic carcinoma. The thymic mass was surgically excised and the dog was treated with pyridostigmine, prednisolone and azathioprine. Serial acetylcholine receptor antibody titres were increased initially but slowly declined to normal values over a period of 24 weeks. Improved exercise tolerance was seen following therapy, however, oesophageal dysfunction persisted. The dog was euthanased 26 weeks after initial presentation due to a complicating illness. A necropsy showed no regrowth or metastasis of the thymic carcinoma.     

Rectal prolapse associated with urinary bladder neoplasia in a cat

A case of feline rectal prolapse which appeared to be secondary to transitional cell carcinoma of the urinary bladder is described. The cat was reported to be incontinent and treatment was declined by the owners. Euthanasia was performed and necropsy revealed an extensive nodular thickening of the entire urinary bladder wall. A diagnosis of urinary bladder transitional cell carcinoma was made on histopathological examination.     

Hypercalcaemia associated with chronic lymphocytic leukaemia in a Giant Schnauzer.

A 7-year-old male Giant Schnauzer was referred with a history of severe vomiting, lethargy, weight loss, polydipsia and polyuria. Detailed investigations revealed leucocytosis with a marked lymphocytosis, mild non-regenerative anaemia, thrombocytopenia, hypercalcaemia and azotaemia. Circulating lymphocytes were small and well-differentiated, and the same lymphoid population was present in bone marrow. Chronic lymphocyctic leukaemia with associated paraneoplastic hypercalcaemia was diagnosed. Immunohistochemical staining of a bone marrow biopsy revealed a neoplastic B-cell line expressing CD79. The dog responded to therapy with prednisolone and chlorambucil for a period of 8 months.     

Acquired immune-mediated myasthenia gravis in a cat associated with a cystic thymus

Acquired myasthenia gravis was diagnosed in a five-year-old domestic shorthair, neutered, female cat with generalised muscle weakness, tremors, dysphagia and alterations in voice. Radiographs indicated the presence of a mass in the anterior thorax. A response to edrophonium chloride, and raised levels of anti-acetylcholine receptor antibodies in the serum, confirmed the diagnosis and indicated an immune-mediated aetiology. Clinical remission occurred following thymectomy and the use of immunosuppressive corticosteroids. This is the first fully-documented case of acquired feline myasthenia gravis associated with the presence of a thymic abnormality in the United Kingdom. The clinical features, laboratory findings and response to treatment are compared with those reported previously in cats and other species.     

Extravasation injury associated with parenteral nutrition in a cat with presumptive gastrinomas

Objective – To describe the pathologic consequences of parenteral nutrition (PN) extravasation into the mediastinum of a cat. Case Summary – An 8‐year‐old domestic short hair cat with persistent vomiting and anorexia was initiated on PN for nutritional support. PN was being administered at a rate of 12.9 mL/h when inadvertent jugular catheter migration resulted in thrombophlebitis and cellulitis and 40–80 mL of PN extravasated into the SC and mediastinal tissues. The cat was euthanized 36 hours after the extravasation of PN due to poor prognosis related to the gastric complications associated with a presumed primary gastrinoma. Grossly there was excessive mediastinal lymphatic drainage and pronounced edema in the cervical SC and mediastinal tissue. Histopathologic examination of the PN‐extravasated area revealed a severe mixed inflammatory reaction, represented by a severe neutrophilic and mild histiocytic infiltrate with lymphoplasmacytic perivascular cuffing. No bacterial agents were observed or cultured from this area. Unique Information Provided – This is the first case report of a foreign body‐type reaction due to extravasation of PN (extravasation injury) in a cat. Extravasation of PN is not without pathologic consequence, and can result in a severe inflammatory reaction in affected tissues.     

Paraneoplastic alopecia associated with internal malignancies in the cat

Abstract A paraneoplastic alopecia associated with internal malignancy is reported in four cats. Acute, bilaterally symmetrical, ventral glistening alopecia, weight loss and lethargy were present in all cats. Skin biopsy specimens exhibited severe follicular and adnexal atrophy with follicular miniaturization, minimal inflammation and, in many cases, absence of stratum corneum. At the time of díagnosis, three cats had a metastatic pancreatic adenocarcinoma and one had a bile duct carcinoma. This report confirms, and expands upon the previous report of a syndrome associating ventral alopecia and metastatic visceral carcinomas in cats. Résumé— Une alopécie paranéoplasique associée à une tumeur interne maligne est observée sur 4 chats. Les symptômes sont caractérisés par une alopécie symétrique et bilatérale sur le ventre avec un aspect brillant et lisse, un amaigrissement, une lethargic Les lésions histopathologiques sont caractérisées par une atrophie folliculaire et annexielle avec des petits follicules pileux, une inflammation dermique discréte et dans beaucoup de cas, une absence du stratum corneum. Trois chats présentent un adénocarcinome pancréatique métastasé et un chat un cholangiocarcinome. Ces cas confirment l'existence d'un syndrome associant une alopécie ventrale et des carcinomes viscéraux métastatiques chez le chat. [Pascal-Tenorio, A., Olivry, T., Gross, T. L., Atlee, B. A., Ihrke, P. J. Paraneoplastic alopecia associated with internal malignancies in the cat. (Alopécie paranéoplasique associée à des tumeurs malignes internes chez le chat.) Veterinary Dermatology 1997; 8 : 47–52.] Resumen Se describe en cuatro gatos una alopecia paraneoplasica asociada a procesos malignos internos. Todos los gatos presentaban una alopecia bilateral, simétrica, ventral, de aspecto brillante, pérdida de peso y letargia. Las biopsias cutáneas mostraron atrofia folicular y adnexal marcada, miniaturización de foliculos, inflamación minima y, en muchos casos, ausencia del estrato córneo. En el momento del díagnóstico, tres de los gatos tenian un adenocarcinoma metastático y uno tenia un carcinoma de conducto biliar. Este articulo confirma y amplia un informe previo sobre el sindrome de alopecia ventral y carcinomas viscerales metastáticos en gatos. [Pascal-Tenorio, A., Olivry, T., Gross, T. L., Atlee, B. A., Ihrke, P. J. Paraneoplastic alopecia associated with internal malignancies in the cat. (Alopecia paraneoplasica asociada a procesos malignos internos en el gato.) Veterinary Dermatology 1997; 8 : 47–52.] Zusammenfassung— Es wird über eine paraneoplastische Alopezie in Verbindung mit inneren malignen Prozessen bei vier Katzen berichtet. Bei alien Katzen traten eine akute bilateral symmetrische ventrale Alopezie, Gewichtsverlust und Lethargie auf. Die Hautbiopsien zeigten eine schwere follikuläre und adnexale Atrophie mit follikulärer Miniaturisation, geringer Entzündung und in vielen Fallen ein Fehlen des Stratum corneum. Zum Zeitpunkt der Diagnose litten drei Katzen an einem metastasierenden Adenokarzinom des Pankreas und eine Katze an einem Gallengangskarzinom. Dieser Bericht erhärtet und erweitert den früheren Bericht über ein Syndrom, das ventrale Alopezie in Verbindung mit metastasierenden Eingeweidekarzinomen bei der Katze beschreibt. (Paraneoplastische Alopezie in Verbindung mit inneren malignen Prozessen bei der Katze.) Veterinary Dermatology 1997; 8 : 47–52.]     

Myasthenia gravis and hypothyroidism in a dog with meningomyelitis

A 12-year-old, spayed female miniature poodle was evaluated because of a 4-day history of paraparesis, dysuria, and tenesmus. Neurological assessment suggested peripheral nervous system dysfunction, predominantly pelvic limb weakness with a possible concurrent sixth lumbar (L(6)) to second sacral (S(2)) myelopathy. Further studies supported the diagnoses of myasthenia gravis, hypothyroidism, and meningomyelitis. To the authors' knowledge, this is the first reported case of concurrent myasthenia gravis and meningomyelitis in the dog. It was unclear whether the identified conditions evolved from a shared etiopathogenesis or were merely coincidental.     

Orbital neoplasia with enophthalmos in a cat

A 9-year-old cat was evaluated for left-sided enophthalmos and protrusion of the third eyelid. A primary orbital fibrosarcoma was diagnosed. During the orbital exploration, normal periorbital fascia could not be identified in the lateral and ventral region, thus accounting for the enophthalmos.     

Acquired myasthenia gravis in a cat with thymoma

A 4-year-old castrated Abyssinian cat was evaluated for profound neuromuscular weakness. Results of electromyography and repetitive nerve stimulation tests were normal. Thoracic radiography revealed a cranial mediastinal mass, which was excised and identified as a thymoma. Serum acetylcholine receptor antibodies were detected at high concentration, supporting a diagnosis of acquired myasthenia gravis. Clinical signs of disease responded to treatment with pyridostigmine and corticosteroids.     

Myasthenia gravis and masticatory muscle myositis in a dog

A 21-month-old, castrated male Vizsla was presented for pelvic limb weakness, difficulty opening his mouth, ptyalism, voice change, and urinary incontinence. Myasthenia gravis and masticatory myositis were diagnosed. The unusual clinical findings, diagnosis, treatment, and case outcome are described, followed by a brief discussion of myasthenia gravis and masticatory myositis.     

Feline paraneoplastic syndrome associated with thymoma

CASE HISTORY: A 6-year-old, spayed, female, domestic short-haired cat presented with severe erythroderma and scaling skin. She showed disturbed gait and mild behavioural changes.

CLINICAL FINDINGS: The cat had a generalised, erythematous, scurfy dermatitis with marked, multifocal crusting and skin thickening. The skin was painful and contracted, which appeared to prevent normal freedom of movement.

DIAGNOSIS: The cat was suspected to have a paraneoplastic syndrome. A mediastinal mass was located and histologically confirmed as thymoma. The cat was diagnosed with a thymoma-associated cutaneous paraneoplastic syndrome.

CLINICAL RELEVANCE: This is a rare condition with few reports in the literature. The skin changes, both grossly and histologically, were considered to be different from those described in cases of paraneoplastic dermatosis associated with pancreatic neoplasia. The clinical presentation was characteristic and more cases may occur in practice than are recognised. In this case, as in previous reports, the tumour was grossly resectable, which could lead to cure of the clinical condition.     

Mediastinal lymphoma in dogs is homogeneous compared to thymic epithelial neoplasia and is more likely to envelop the cranial vena cava in CT images

In order to identify CT signs that could be used to distinguish cranial mediastinal lymphoma and thymic epithelial neoplasia, a retrospective case‐control study was done. Associations between CT signs and diagnosis were tested using binary logistic regression and results expressed as odds ratio and 95% confidence interval. Sixty‐two dogs that had thoracic CT and confirmed diagnosis of lymphoma (n = 33) or thymic neoplasia (n = 29) were sampled. Thymic neoplasms included 24 thymomas and five thymic carcinomas. Dogs with thymic epithelial neoplasia were significantly older than dogs with lymphoma (median age 8.6 years versus 6.0 years, P = .007), but there were no significant differences in prevalence of clinical signs. Diagnosis of thymic epithelial neoplasia was associated with heterogeneous attenuation in pre‐ (odds ratio 23.3, 95% confidence interval, 4.5‐121.1) and post‐contrast (odds ratio 30.7, 95% confidence interval, 3.6‐265.0) images. Conversely, envelopment of the cranial vena cava by the mass was less likely with thymic epithelial neoplasia than lymphoma (odds ratio 0.07, 95% confidence interval, 0.007‐0.66). Greater standard deviation of Hounsfield unit values in post‐contrast images was associated with thymic epithelial neoplasia (P = .005). Based on ROC analysis, SD > 17HU of the mass in post‐contrast images had a sensitivity of 72% and specificity of 79% for thymic epithelial neoplasia. There were no significant differences in morphology, prevalence of calcification, mediastinal lymphadenopathy, cranial vena cava invasion, collateral vessels, or pleural fluid associated with these tumors. Thymic epithelial neoplasms tended to occur in older dogs and were heterogeneous in CT images, whereas mediastinal lymphoma was more homogeneous and more likely to envelop the cranial vena cava.     

Hyperalbuminemia associated with hepatocellular carcinoma in a dog

Abstract: A 12‐year‐old, neutered male, mixed‐breed dog was presented to The Ohio State University Veterinary Teaching Hospital with a history of weight loss and weakness. Laboratory abnormalities reported by the referring veterinarian during the past year included increased alkaline phosphatase (ALP) activity, hyperalbuminemia, and nonregenerative anemia. On referral, the dog appeared hydrated and had moderate muscle wasting and hepatomegaly. A large lobular hepatic mass was observed ultrasonographically. Laboratory results included mild to moderate nonregenerative anemia, urine‐specific gravity of 1.035, 3+ proteinuria, increased serum activities of alanine aminotransferase (229 U/L, reference interval 10–55 U/L), ALP (813 U/L, reference interval 15–120 U/L), and the steroid‐induced isoform of ALP (676 U/L, reference interval 0–6 U/L), marked hyperalbuminemia (5.3 g/dL, reference interval 2.9–4.2 g/dL), and an increased A/G ratio (1.7). Hyperalbuminemia was confirmed by reanalysis on 2 different analyzers and by agarose gel electrophoresis, and colloid osmotic pressure (COP) was markedly increased (42.5 mmHg, reference interval 20–25 mmHg). Cytologic examination of a fine‐needle aspirate of the hepatic mass indicated hepatocellular proliferation; histologic examination of an excisional biopsy confirmed hepatocellular carcinoma. Three weeks after surgery, the albumin concentration, A/G ratio, COP, and ALT activity had normalized, but ALP activities remained high. We hypothesized that hyperalbuminemia developed secondary to hepatocellular carcinoma due to increased synthesis of albumin by malignant hepatocytes or due to decreased negative feedback from impaired hepatocellular osmoreceptivity. Hepatocellular carcinoma has been associated with paraneoplastic secretion of other proteins, but hyperalbuminemia has been reported only once in a human patient and has not previously in dogs.