Dermal intravascular leiomyosarcoma in a cat

A 10-year-old female spayed domestic shorthaired cat presented with a subcutaneous tumor between the first and second phalanges of the left hind foot. Six months after excision, a similar tumor occurred on the medial aspect of the third phalanx of the same limb. Histologically, both tumors consisted of solid masses of spindle and round cells, many of which grew within endothelial-lined vessels. Tumor cells stained positively for smooth muscle actin and vimentin, but were negative for cytokeratin, S-100, desmin, synaptophysin, factor VIII-related antigen, and neuron-specific enolase. The diagnosis was dermal intravascular leiomyosarcoma.     

Pulmonary intravascular hemangiosarcoma in a cat

A 9-year-old, castrated male Japanese domestic cat presented with a complaint of exertional dyspnea. Based on the radiographic findings, presumptive diagnosis of aspiration pneumonia or primary diffuse pulmonary neoplasia in the right middle lobe was made. Histologically, the pulmonary lesion was characterized by diffuse thickening of alveolar wall with the proliferation of apparently atypical irregular-shaped cells. Immunohistochemical staining using anti-human factor VIII-related antigen antiserum showed positive reaction in the cytoplasm of the atypical cells. According to the findings, the lesion was diagnosed as pulmonary intravascular hemangiosarcoma.     

Chlorambucil-induced myoclonus in a cat with lymphoma

Chlorambucil is an alkylating agent commonly used in veterinary oncology for conditions including lymphoma. Chlorambucil neurotoxicity has been well recognized in human patients. Onsets of central nervous system signs, such as myoclonus, tremors, muscular twitching, agitation, and tonic-clonic seizures, have been reported in humans and laboratory animals treated with chlorambucil. This case of a cat with intestinal lymphoma represents the first veterinary patient reported to have chlorambucil-induced neurotoxicity. Neurotoxicity should be considered a potential side effect of chlorambucil therapy in veterinary patients.     

Hypernatremia associated with intracranial B-cell lymphoma in a cat

An 8-year-old, spayed female, domestic shorthair cat with a history of hyperthyroidism, anorexia, dehydration, cervical ventroflexion, and behavioral changes was referred to the Iowa State University College of Veterinary Medicine. The cat was obtunded, with severe dehydration (15%) and hypothermia (86 degrees F), and severe muscle atrophy and fasciculations. Serum biochemical abnormalities included severe hypernatremia (195 mmol/L, reference interval 155-165 mmol/L), hyperchloridemia (161 mmol/L, reference interval 123-131 mmol/L), and hypokalemia (3.6 mmol/L, reference interval 4.0-5.7 mmol/L). Calculated osmolality was 418 mOsm/kg (reference interval 280-305 mOsm/kg), attributable to the hypernatremia. The cat was kept warm and given fluid and glucocorticoid therapy and supportive measures but remained unresponsive. Hypernatremia and hyperosmolality improved through day 3, when the cat died suddenly. At necropsy, a 1.25-cm mass was found in the area of the thalamus and interthalamic adhesion that extended to the ventral aspect of the cerebrum. The histologic and immunohistochemical diagnosis was B-cell lymphoma. Hypernatremia and hyperosmolality in this cat were attributed to primary adipsia and hypothalamic dysfunction secondary to effacement of central nervous system tissue by neoplastic lymphocytes. To the authors' knowledge, this is the first reported case of central nervous system lymphoma, confirmed by use of immunohistochemical analysis as a B-cell phenotype, associated with hypernatremia. It also is the first reported case of lymphoma in animals limited to the thalamus, hypothalamus, and cerebrum, with no involvement of the spinal cord.     

Canine intravascular lymphoma with overt leukemia

A 6-year-old spayed Labrador Retriever Mix dog was evaluated for a 2-week history of progressive generalized weakness and reluctance to stand. Physical examination revealed severe weakness with obtunded mentation, head tilt, bilateral nystagmus, and decreased vision. CBC findings included mild nonregenerative anemia, marked thrombocytopenia, and a few atypical mononuclear cells on the blood film. The cells were 15-30 μm in diameter and had round to oval to reniform centrally placed nuclei with stippled chromatin, prominent nucleoli, and abundant basophilic cytoplasm with numerous discrete vacuoles and, occasionally, small azurophilic granules. Similar cells were found in bone marrow. On histologic examination of tissues collected at necropsy, neoplastic cells were detected in bone marrow, hepatic sinusoids, cerebral and meningeal vessels, and in capillaries of the heart, renal interstitium, small intestinal submucosa, and muscularis, and alveolar septa. A small discrete mass in the right atrium consisted of similar neoplastic cells, and the spleen was diffusely infiltrated. Tissue distribution was suggestive of intravascular lymphoma. Neoplastic cells in tissue sections were immunoreactive for vimentin, CD18, CD45, and granzyme B and lacked immunoreactivity for cytokeratin. Neoplastic cells on bone marrow aspirate smears and blood films lacked immunoreactivity for CD3, CD79a, CD1c, CD11b, CD11c, CD11d, and E-cadherin. In the absence of immunophenotypic evidence for the neoplastic cells being derived from B-cell, T-cell, or histocytic/dendritic lineages and the lack of clonal antigen receptor gene rearrangement(s), along with positive immunoreactivity for granzyme B, a tumor of NK cells was considered likely. Based on current knowledge, this is the first report of canine intravascular lymphoma, of probable NK cell origin, with peripheral blood involvement.     

Cutaneous lymphoplasmacytic lymphoma with systemic metastasis in a cat

A lymphoplasmacytic lymphoma was diagnosed in a 12- year-old domestic cat that had a primary cutaneous mass involving the stomach, liver, kidneys, heart, abdominal wall, diaphragm, bone marrow and several lymph nodes. Histopathologically, the most characteristic feature of this tumor was the heterogeneity of cell components, such as small lymphocytes, well-differentiated plasma cells and plasmacytoid transformed lymphocytes. Amyloid was deposited in the skin, stomach, and several lymph nodes. Immunohistochemically, neoplastic small lymphocytes were positive for CD20, and well-differentiated plasma cells and plasmacytoid transformed lymphocytes were positive for λ-Ig light chains and MUM1/IRF-4. These results emphasize the importance of lymphoplasmacytic lymphoma as a differential diagnosis of extramedullary cutaneous plasmacytoma in cats.     

B-cell conjunctival lymphoma in a cat

A bilateral conjunctival neoplasm was surgically removed from a 13-year-old Domestic Short-haired female cat and examined by histopathology. The neoplasm was infiltrative, nonencapsulated and composed of large sheets of densely packed, round to polygonal cells. Neoplastic cells were variably sized with scant to modest amounts of cytoplasm and oval to round nuclei. On immunohistochemistry the neoplastic cells stained positively for BLA.36 and negative for CD-3 antibodies. On the basis of histopathology and immunohistochemical findings, a diagnosis of conjunctival B-cell lymphoma was made. This is the first case with immunohistochemical characterization of conjunctival lymphoma in a cat.     

A case of otitis in a domestic cat

A case of otitis media and interna in a domestic cat is described in which granulation tissue extended into the external ear canal. An unusual histological feature was the presence of mucous glands within the granulation tissue. The possible origin of these glands and a differential diagnosis of this condition is discussed.     

A case of myasthenia gravis in a cat

A case of myasthenia gravis in a cat, the second to be recorded in this species, is described. A good response was obtained to oral administration of 10 mg pyridostigmine daily, preceded by 0–15 mg atropine sulphate to obviate the cholinergic effects. The cat showed no recurrence of muscular weakness 6 months after treatment was terminated. Attention is drawn to a dilation of the oesophagus, which is a feature of the condition in dogs and which was also seen in this feline case. The extent of the dilation differs in the dog and the cat and appears to be dependent upon the anatomical distribution of striated muscle in the oesophagus of the two species.     

A case of hyperplastic gastropathy in a cat

Primary hyperplastic gastropathy is an uncommon human disease characterized by giant gastric mucosal folds and is associated with a spectrum of histopathological changes. Diagnosis is usually made on radiological and gastroscopic findings followed by full-thickness biopsy of the stomach wall. The aetiology is unknown and symptomatic treatment is usually disappointing. A similar condition has been described in a small number of dogs. A case of hyperplastic gastropathy is reported in a cat and compared with the findings in man and dogs. The cat presented with chronic vomiting and weight loss. Radiological and gastroscopic examinations revealed enlarged gastric rugae. Medical and surgical treatment was unsuccessful and the cat was destroyed. The pathological findings were similar to those described in man.     

A case of conjunctival melanoma in a cat

Since 1985, 5 cases of feline conjunctival melanoma have been reported in the literature. Information on feline conjunctival melanoma epidemiological features, localizations, macroscopic features and histological features is limited. We are describing the clinical, histopathologic features and outcomes in a cat that presented clinically with a slow developing dark brown mass located under the upper eyelid of the left eye. Pertinent literature is reviewed; and the recognizable clinical features and treatment are discussed. The mass was surgically resected. Despite its size, the lesion was easily separated from underlying tissues, making possible a macroscopic complete resection that left intact the adjacent conjunctiva. The tumour histological examination has showed a pigmented melanoma lacking encapsulation, but presenting a clear zone delimiting the lesion. It was exclusively composed of epithelioid cells, and presented mild cellular anaplasia and weak mitotic activity. These features allowed it to be classified as a quite differentiated melanoma with few signs of potential malignancy. In accordance with these histologic features, no recurrence has been registered 34 months after surgery. Thus, a favorable outcome is now reported for two out of six cases of conjunctival melanoma in the cat. This report also confirms the predilection for this neoplasm to arise from the bulbar conjunctiva.     

A case of ectopic pregnancy in a cat

Radiography of the abdomen of a Siamese cat revealed an ectopic pregnancy. It is believed that normal pregnancies had taken place after the occurrence of the abdominal pregnancy. Résumé. Une radiographie de l'abdomen d'un chat siamois a révélé une grossesse ectopique. On a pensé que des grossesses normales avaient eu lieu après l'occurrence d'une grossesse abdominale. Zusammenfassung. Radiographie von dem Unterleib einer Siamesischen Katze zeigten eine nichtnormalgelagerte Schwangerschaft. Man vermutet dass normale Schwangerschaften nach diesem Vorfall von Bauchhǒhlenschwangerschaft, stattfanden.     

A probable case of hypoparathyroidism in a cat

Idiopathic hypoparathyroidism was suspected in a young female cat. The relevant historical and clinical findings were: anorexia, intermittent muscle tremors, hindlimb ataxia, behavioural changes and cataracts. Salient laboratory findings were: hypocalcaemia, hyperphosphataemia and normal renal function (normal serum urea and creatinine concentrations with hypersthenuria). No evidence of intestinal malabsorption, pancreatitis or nutritional secondary hyperparathyroidism was found. Treatment with oral synthetic vitamin D (1,25 dihydroxycholecalciferol) and intravenous and oral calcium supplements was successful in correcting the hypocalcaemia and abolishing the clinical signs.     

Retrobulbar lymphoma associated with a ballistic foreign body in a cat

A seven‐year‐old domestic shorthair cat, adopted 5 years previously with a corneal perforation of the left eye, was presented for investigation of a left orbital mass. Computed tomography revealed a metallic foreign body within a contrast‐enhancing, heterogeneous orbital mass. Large cell lymphoma was diagnosed from a fine needle aspirate. The cat staged negatively and was treated with l‐asparaginase, prednisolone and three fractions of radiation therapy. A rapid clinical remission was obtained and the cat remained in remission for 3 years after therapy. This is the first report of large cell lymphoma likely occurring secondary to a foreign body.     

B-cell immunoblastic lymphoma with multinucleated giant cells in a cat

A 10-year-old male mixed breed cat died after six months history of intermittent vomiting and weight loss. At necropsy, large white-colored foci were found in both kidneys, and whitish thickening of the gastric wall was present at the pyloric part of the stomach. Histopathological examination revealed that both lesions consisted of proliferation of large-sized neoplastic lymphocytes intermingled with multinucleated giant cells. Immunohistochemically, the neoplastic cells were positive for both B-cell antigen receptor complex (CD 79 alpha cy) and MHC class II, although multinucleated giant cells were negative. The present case was diagnosed as B-cell immunoblastic lymphoma with multinucleated giant cells.     

Intestinal T-cell lymphoma with severe hypereosinophilic syndrome in a cat

A Japanese domestic long-hair cat of about 8 years of age was presented with vomiting and hematochezia and was found to have significant hypereosinophilia. Bone marrow aspiration revealed moderate increases of eosinophilic lineages. Histopathological examination revealed mild eosinophilic and epitheliotropic T-lymphocytic infiltrations in the duodenum. Although the cat remained asymptomatic with only prednisolone administration, the cat presented with hematemesis, weight loss, and severe anorexia 512 days after the initial presentation. Subsequently, gastrointestinal perforation developed, and the cat died on Day 536. Histopathological examination of autopsy specimens revealed mixed cellular infiltration including eosinophils and neoplastic lymphocytes in the intestinal lymph nodes, intestine, liver, spleen, and pancreas. Immunohistochemical examination supports a diagnosis of intestinal T-cell lymphoma with severe hypereosinophilic syndrome.     

Extranodal conjunctival Hodgkin's-like lymphoma in a cat

A seven-year-old female spayed Domestic Short-haired cat was brought for examination following a four-month history of conjunctivitis in the right eye. The superior palpebral conjunctiva was diffusely swollen and firm, displacing the right globe ventrally and preventing full closure of the eyelids. The right popliteal lymph node was enlarged as were several other peripheral lymph nodes. An incisional biopsy of the conjunctival swelling revealed a lymphoid neoplasm, the cellular make up of which suggested features of feline Hodgkin's-like lymphoma. Although the neoplasm was poorly responsive to standard chemotherapeutic protocols for lymphoma, radiation therapy rapidly reduced its size. Three years following the initial diagnosis, there has been no recurrence of the conjunctival neoplasm. To the authors' knowledge, there are no previous reports of extranodal or adnexal (conjunctiva, eyelid, orbit) Hodgkin's-like lymphoma in the veterinary literature.