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.     

Mediastinal lymphoma in a young Turkish Angora cat

An 8-month old intact male Turkish Angora cat was referred to the Veterinary Medical Teaching Hospital (VMTH), Seoul National University, for an evaluation of anorexia and severe dyspnea. The thoracic radiographs revealed significant pleural effusion. A cytology evaluation of the pleural fluid strongly suggested a lymphoma containing variable sized lymphocytes with frequent mitotic figures and prominent nucleoli. The feline leukemia virus and feline immunodeficiency virus tests were negative. The cat was euthanized at his owner''s request and a necropsy was performed. A mass was detected on the mediastinum and lung lobes. A histopathology evaluation confirmed the mass to be a lymphoma. Immunohistochemistry revealed the mass to be CD3 positive. In conclusion, the cat was diagnosed as a T-cell mediastinal lymphoma.     

Large anaplastic spinal B‐cell lymphoma in a cat

Abstract: A 5‐year‐old female spayed domestic shorthair cat was presented for evaluation of tetraparesis. The neurologic lesion was localized to the cervical spinal segment (C1–C6). A left axillary mass was identified, and the results of fine needle aspiration cytology indicated malignant round cell neoplasia of possible histiocytic origin. The cells were large, had marked anisocytosis and anisokaryosis, occasional bi‐ and multinucleation, and cytoplasmic vacuolation. Euthanasia was performed due to the poor prognosis associated with severe, progressive neurologic signs and a malignant neoplasm. Postmortem examination revealed spinal cord compression and an extradural mass at the C1–C2 spinal segment, with neoplastic cells in the adjacent vertebral bodies, surrounding skeletal muscle, left axillary lymph node, and bone marrow from the right femur. The initial histologic diagnosis was anaplastic sarcoma, but immunohistochemical results indicated the cells were CD20+ and CD45R+ and CD3?, compatible with a diagnosis of B‐cell lymphoma. CD79a staining was nonspecific and uninterpretable. Weak to moderate CD18 positivity and E‐cadherin positivity were also observed. Clonality of the B‐cell population could not be demonstrated using PCR testing for antigen receptor gene rearrangement. To the authors' knowledge, this is the first reported case of a feline spinal anaplastic B‐cell lymphoma exhibiting bi‐ and multinucleated cells. The prognostic significance of this cell morphology and immunophenotype is unknown.     

Hemangiosarcoma of the third eyelid in a cat

A case of hemangiosarcoma of the third eyelid in a 15-year-old Domestic Short-haired cat is reported. A small red mass protruding from the anterior surface of the third eyelid in the left eye was present. Only mild bilateral conjunctivitis and nuclear sclerosis were revealed on initial ophthalmic examination. After anti-inflammatory treatment, surgery and cryotherapy were performed. On histopathologic examination the mass was located just beneath the conjunctival epithelium, suggesting that the conjunctiva was the tissue of origin. The tumor showed high cellularity and was composed of pleomorphic spindle and polygonal cells arranged in interlacing bundles and solid sheets. The presence of slit-like spaces between tumor cells containing erythrocytes demonstrated the vascular differentiation. Mitotic activity was moderate, but atypical mitoses were detected. The surgical area healed uneventfully and after 7 months there was no recurrence. To the authors' knowledge, this is the first report of conjunctival hemangiosarcoma of the third eyelid in a cat.     

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.     

Histopathologic classification of 171 cases of canine and feline non-Hodgkin lymphoma according to the WHO

A retrospective collection of 171 lymphoid neoplasms (123 dogs and 48 cats) was classified according to the Revised European–American Lymphoma (REAL) classification, adopted in 2002 by the World Health Organization (WHO), to evaluate the WHO system for categorization of canine and feline neoplasms. Microscopic examination was performed after standard hematoxylin–eosin staining and immunohistochemical labelling for B (CD79a) or T (CD3) cell phenotypes. B-cell lymphomas were prevalent in dogs and T-cell lymphomas in cats. B-Large cell lymphoma (B-LCL) frequently showed plasmacytoid differentiation; notably, two canine plasma cell tumours (PCT) expressed both CD79 and CD3. There were difficulties in differentiating B-lymphoblastic lymphoma (B-LBL) from Burkitt-type lymphoma. Furthermore, intestinal T-cell lymphoma (ITCL) exhibited a huge morphologic variability. Finally, multicentric mature small and thymic T-cell lymphomas were diagnosed, although these categories are not codified by the WHO classification.     

Corneal hemangiosarcoma in a cat

A 10 year-old castrated male Domestic Short-hair cat with a history of chronic bilateral keratitis was referred for assessment of a red, elevated mass involving the left cornea. The rapid growth of the mass, over a month period in combination with pronounced vascularization and invasion of the corneal surface suggested an aggressive inflammatory or neoplastic process. Following keratectomy, the lesion was diagnosed histopathologically as a hemangiosarcoma. The tumor recurred locally within 3 weeks and enucleation was performed. Histopathologic examination of the globe confirmed the diagnosis and did not reveal infiltration of the limbus and conjunctiva. No signs of local recurrence or metastatic disease have been observed 18 months following enucleation. To the authors' knowledge this is the first case of primary corneal hemangiosarcoma described in the feline species.     

What is your diagnosis? Cervical mass in a cat

An 8-year-old female spayed domestic shorthair cat was presented for several months of weight loss, decreased appetite, and 2 bilateral, ventral cervical masses. Initial cytologic samples were interpreted as reactive lymphoid hyperplasia. Evaluation of subsequent mass aspirates revealed small numbers of large binucleated and multinucleated cells resembling Reed-Sternberg cells admixed with more numerous small and intermediate-sized lymphocytes. In histopathologic sections, the normal architecture of the lymph node was largely effaced by a slightly heterogeneous mass composed of round cells arranged in densely cellular sheets with a minor population of large (25-mum diameter) mononuclear cells and a few very large (30-40-mum diameter) binucleated or multinucleated cells interpreted as Reed-Sternberg-like cells. Immunohistochemically, the large neoplastic (Reed-Sternberg-like) cells were negative for CD18, CD3, CD20, and CD79a while the background population consisted of about 70% T cells and 30% B cells. This pattern of immunohistochemical staining along with cytologic and histopathologic findings supported a diagnosis of Hodgkin's-like lymphoma, specifically, the lymphocyte-rich subtype. Hodgkin's-like lymphoma has been reported previously in cats and should be suspected when Reed-Sternberg-like cells are observed in cytologic preparations of lymph node aspirates. Histopathology and immunohistochemistry are necessary for a definitive diagnosis.     

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.     

Bronchogenic adenocarcinoma in a cat: an unusual case of metastasis to the skin

A 6-year-old, spayed, female, domestic shorthair cat was presented for decreased activity. A nodular lesion was found in the skin extending into the subcutaneous tissue of the right abdominal flank. On lateral and ventrodorsal radiographs of the thorax, an opacity involving the entire right caudal lung lobe and pleural effusion were noted. Cytologic evaluation of cells in the thoracic fluid and in the mass revealed a population of atypical epipthelial cells with marked anisocytosis and high N:C ratios, organized in acinar-like clusters. Multinucleated cells and several mitotic figures were found. The cytologic interpretation was carcinoma. Because of the progressive severity of clinical signs, the cat was euthanized. Histologic evaluation of tissues obtained at necropsy indicated a bronchogenic adenocarcinoma in the lung, with metastasis to the skin of the right flank, but no involvement of the digits. Based on immunohistochemical stains, the neoplastic cells strongly co-expressed cytokeratin and vimentin, and were negative for S-100 and actin-specific antigen. Bronchogenic adenocarcinoma is an uncommon neoplasm in cats, and the digits are the most common sites of metastasis. This case was unusual in that the skin of the abdominal wall was the primary site of metastasis, with no involvement of the digits.     

Surgical correction of aberrant conjunctival overgrowth in a rabbit: a case report

A dwarf rabbit presented with unilateral aberrant conjunctival growth. Allgoewer’s U-suture therapy was initially used to correct the overgrowth. Centrifugal incisions extending up to the limbus were made on the hypertrophic conjunctiva. Transpalpebral limbal fixation was performed next. When the symptoms recurred 3 weeks later, a second operation was performed using the Lembert suture method instead. The overgrowing membrane was excised radically just posterior to the limbus. The conjunctiva was then sutured using the Lembert pattern. The rabbit recovered with no further complications.     

Extranodal γδ-T-cell lymphoma in a dog with leishmaniasis

Abstract: An 8-year-old intact male mongrel dog with alopecia and weight loss was referred to the Veterinary Faculty of Naples. The dog had pale mucous membranes, enlarged prescapular lymph nodes, and splenomegaly. Laboratory abnormalities included anemia, thrombocytopenia, and hyperglobulinemia. Bone marrow aspirate smears contained numerous Leishmania amastigotes and an immunofluorescent antibody titer was strongly positive (1:1280) for leishmaniasis. The dog was treated with a combination of meglumine antimoniate and allopurinol for 60 days and showed clinical improvement. Two months after the end of treatment the dog was again referred because of relapse of leishmaniasis and the presence of a firm subcutaneous mass on the medial right thigh. Based on cytologic examination of fine needle aspirates of the mass, a diagnosis of large-cell lymphoma was made. Flow cytometry of tumor cells revealed γδ-T-cell lymphoma with a CD5+, CD3+, TCRγδ+, CD4−, CD8−, CD45RA+ immunophenotype. Using nested PCR, amastigotes were not detected in the neoplastic tissue. An association between leishmaniasis and hematopoietic tumors has been described rarely. γδ-T cells may be involved in the host response to this parasite, and prolonged antigenic stimulation and chronic immunosuppression (typical of leishmaniasis) play a crucial role in the etiopathogenesis of T-cell lymphoma.     

Carcinosarcoma mimicking a feline injection‐site sarcoma in a cat

A 15‐year‐old spayed female domestic short‐haired cat with cutaneous/subcutaneous well‐circumscribed, alopecic mass approximately 25 × 30 mm in diameter, localized to the left shoulder region was brought to the veterinary surgery department. Despite the suggestive location and macroscopic appearance, feline injection‐site sarcoma was not suspected based on the cytologic examination of fine‐needle aspirates. The tumor was surgically resected, and tissue sections were evaluated microscopically. The tumor was found to be nonencapsulated with a distinct border between the neoplastic parenchyma and surrounding connective tissue. The neoplastic tissue consisted of 2 cell populations: elongated to spindle‐shaped cells arranged in bands and cords and malignant epithelial‐like cells. Both populations showed microscopic features of malignancy. Multinucleate giant cells with irregular cytoplasm were scattered among the neoplastic cells. The spindle‐shaped cells strongly expressed vimentin but did not express α‐smooth muscle actin (α‐SMA) or cytokeratin. Desmin was strongly expressed in about 0‐5% of cells. Epithelial‐like cells expressed cytokeratin, but not vimentin, desmin, or α‐SMA. Multinucleate giant cells expressed vimentin, but did not α‐SMA, desmin, or cytokeratin. Based on microscopic observations and IHC results, the final diagnosis was carcinosarcoma with histologic features compatible with feline injection‐site sarcoma, but without the clinical aggressiveness of this tumor.     

p53 protein expression in conjunctival squamous cell carcinomas of domestic animals

The expression of p53 protein was investigated in eight formalin-fixed, paraffin-embedded conjunctival squamous cell carcinomas of five horses and one cow, dog and cat each by an immunohistochemical procedure in order to evaluate protein overexpression. Anti-human p53 protein mouse monoclonal antibodies known to be cross-reactive with p53 protein of the animal species examined were used. Positive p53 nuclear immunostaining was detected in five equine, one bovine and one feline cases. Conversely, no p53 immunostaining was found in the only canine case examined. These results demonstrate a frequent p53 overexpression in conjunctival squamous cell carcinoma that could be related to UV-induced mutations of the p53 tumor suppressor gene.     

Presumptive precursor-targeted immune-mediated anemia concurrent with gastrointestinal lymphoma in a cat

A 10-year-old spayed female mixed-breed cat presented with progressive nonregenerative anemia. Clinicopathological abnormalities included severe nonregenerative anemia (packed cell volume [PCV]: 7%, aggregate reticulocytes: 1.12 × 10³/µl) and a hypoechogenic mass well-localized in the stomach. Bone marrow (BM) smears revealed increased particle hematopoietic cellularity with decreased myeloid:erythroid (M:E) ratios, no dysplasia of any lineage, and presence of erythroid precursors phagocytized by macrophages. The cat was diagnosed with presumptive precursor-targeted immune-mediated anemia (PIMA). The stomach mass was consistent with CD 20 positive T-cell lymphoma. The lymphoma was completely resected via surgery, and the PIMA was cured by immunosuppressive therapy. On day 410, both diseases have not recurred without medications. This is the first report of feline PIMA and concurrent gastrointestinal lymphoma.     

Presumptive primary cardiac lymphoma in a cat causing pericardial effusion

We report a case of primary cardiac lymphoma in a cat, causing pericardial effusion. A 13-year-old castrated male Himalayan cat was evaluated for chronic weight loss and radiographic finding of cardiomegaly. Pericardial effusion and a heart mass were detected via echocardiography. Pericardiocentesis and ultrasound-guided fine needle aspirate of the heart mass were performed under sedation. Antemortem diagnosis of cardiac lymphoma was made based on cytology of pericardial fluid. Based on physical examination, laboratory tests and abdominal radiographs, primary cardiac lymphoma was established as the presumptive clinical diagnosis. Treatment with chemotherapeutic agents was initiated.     

Morphologic, immunohistochemical, and molecular characterization of hepatosplenic T-cell lymphoma in a dog

A 13-year-old neutered male Jack Russell Terrier (Parson Russell Terrier) was presented to the Texas Veterinary Medical Center with a history of lethargy, depression, vomiting, and fever. The dog had mildly regenerative anemia, severe thrombocytopenia and low antithrombin activity. Marked splenomegaly was found on physical examination and imaging studies, and malignant round cell neoplasia and marked extramedullary hematopoiesis were diagnosed on aspirates of the spleen. The dog underwent exploratory laporatomy and splenectomy. Because of a rapid decline in clinical condition postsurgery, the dog was euthanized. Splenic and hepatic biopsies were submitted for histopathologic evaluation. A neoplastic population of round cells was found throughout the splenic parenchyma and within hepatic sinusoids. The neoplastic cells stained strongly positive for CD3 (T-cell marker) and were negative for CD79a (B-cell marker) and lysozyme (histiocytic marker). A diagnosis of T-cell lymphoma was confirmed by assessment of T-cell clonality using canine-specific polymerase chain reaction-based techniques. Although expression of the gammadelta T-cell receptor was not evaluated, this case shares many similarities with a rare syndrome in humans known as hepatosplenic gammadelta T-cell lymphoma.     

Multiple cutaneous histiocytomas in a cat

A 15-year-old domestic long haired cat developed nodular cutaneous masses over the right shoulder that were removed surgically. Similar masses developed in multiple cutaneous sites over the following three years. In each case, the lesions were characterized by diffuse dermal infiltration by histiocytic cells with a low mitotic rate and evidence of epidermotropism. The neoplastic population uniformly expressed class II molecules of the Major Histocompatibility Complex, but did not express the T and B lymphoid markers CD3 and CD79. Perivascular aggregates of CD3⁺ T lymphocytes were located at the deep margins of the tumour nodules. The clinical, histopathological and immunohistochemical features of these tumours are consistent with cutaneous histiocytoma. This tumour has not been previously well-documented in the cat.     

Identification of domestic cat hepadnavirus from a cat blood sample in Japan

The hepatitis B virus (Hepadnaviridae) induces chronic hepatitis and hepatic cancer in humans. A novel domestic cat hepadnavirus (DCH) was recently identified in several countries, however, the DCH infection status of cats in Japan is unknown. Therefore, we investigated the DCH infection rate of 139 cat samples collected in Japan. We identified one positive blood sample (0.78%) from a 17-year-old female cat with chronically elevated alanine aminotransferase. Phylogenetic analysis demonstrated that the DCH strain identified in this study is genetically different from strains in other countries. Further investigations are required to elucidate the evolution of DCH and the impact of DCH infection on hepatic diseases in domestic cats.     

Staphyloma in a cat

A unilateral scleral staphyloma in an 18-month-old, female spayed Domestic Short-haired cat was treated with excision, primary closure and fascial graft. Other ocular abnormalities noted on examination included iris coloboma, anterior cortical cataract, focal lens equator flattening and retinal dysplasia. The staphyloma was presumed to be congenital in origin.