Localized pleural mesothelioma in a dog.

Malignant mesotheliomas with localized growth are extremely rare in dogs. A 9-year-old male dog presented with a localized tumour that originated from the parietal pleura and had polypoid growth in the thoracic cavity. Histological examination revealed that the tumour consisted of tubular formations with scattered cysts and minimal papillary growth pattern. Neoplastic cells were immunopositive for mesothelial markers (calretinin and Wilms' tumour gene 1) and negative for carcinoma markers (thyroid transcription factor 1 and tumour protein 63). The animal was alive with no recurrence or metastasis/dissemination 11 months after surgery. To the best of our knowledge, this is the first report of a localized mesothelioma in a dog without metastasis/dissemination and highlights the value of mesothelial markers for an accurate diagnosis.

Pleural mesothelioma in a California sea lion (Zalophus californianus).

A 25-year-old female California sea lion (Zalophus californianus) reared in an aquarium died following a history of anorexia, lethargy, abnormal protrusion of the skin, and oral respiration. At necropsy, multiple yellowish-white nodules with diameters of 0.1-0.5 cm were disseminated in the thoracic cavity and lungs. Histopathologically, the nodules were continuous with normal mesothelium and were characterized by the proliferation of spindle-shaped to polygonal neoplastic cells with prominent atypia. The neoplastic cells exhibited diffuse, strong staining for vimentin and partial, weak to moderate staining for cytokeratin AE1/AE3. Based on these findings, the lesions were diagnosed as pleural mesothelioma. This study reports the first case of pleural mesothelioma in California sea lion.

Pericardial malignant mesothelioma diagnosed in a dog by immunocytochemistry of the pericardial fluid: a case report.

BACKGROUND: Pericardial effusions are one of the most common cardiac diseases in dogs. Common causes of haemorrhagic pericardial effusions include neoplasia, such as hemangiosarcoma, mesothelioma, chemodectoma, and ectopic thyroid tumours, and benign idiopathic pericardial effusion. Distinguishing among reactive mesothelial cells, malignant mesothelioma, and adenocarcinoma in body effusions is a diagnostic challenge. Therefore, the author aimed to discover whether the observed cells were reactive mesothelial, mesothelioma, or adenocarcinoma cells through immunocytochemistry using five markers (cytokeratin, vimentin, desmin, E-cadherin, and calretinin) in a canine patient. CASE PRESENTATION: A 2.1 kg, spayed female, 10-year-old Yorkshire Terrier dog presented to a local hospital with dyspnoea and was evaluated for pericardial effusion. The presence of pericardial fluid was confirmed, and she was referred to our hospital for further evaluation. In cytological evaluation, cells shed individually or in clusters were observed, along with numerous non-degenerative neutrophils and macrophages. The cells showed binucleation, anisocytosis, anisokaryosis, abnormal nucleoli, abundant basophilic cytoplasm, high nuclear-cytoplasmic ratio, and coarse chromatin. Large atypical multinucleate cells were also observed. Erythrophagia was observed, indicating chronic haemorrhage. Immunocytochemistry using pericardial fluid was positive for cytokeratin, vimentin, desmin, E-cadherin, and calretinin. Therefore, malignant mesothelioma was diagnosed. CONCLUSIONS: Immunocytochemistry is a very useful diagnostic technique because it can determine whether several fluorescent markers are simultaneously expressed in the same cell. Further, E-cadherin and calretinin can be used for the differential diagnosis of reactive mesothelial cells, malignant mesothelioma, and adenocarcinoma in dogs.

Utility of 5-aminolaevulinic acid fluorescence-guided endoscopic biopsy for malignant mesothelioma in a cat and dog.

Malignant mesothelioma (MM) is uncommon in cats and dogs and can be challenging to diagnose. Adequate tissue sampling is required for superior diagnostic accuracy. Protoporphyrin IX, a metabolite of 5-aminolaevulinic acid (5-ALA), is a photosensitiser for photodynamic diagnosis (PDD). To the best of our knowledge, no study has reported the use of 5-ALA-PDD to detect MM in veterinary medicine. The present study describes the use of 5-ALA-PDD for MM diagnosis in a cat and dog, as well as the effectiveness of intracavitary chemotherapy. We evaluated the use of PDD with 5-ALA hydrochloride (5-ALA-PDD) in two cases of MM. A 12-year-old cat presented with a 1-month history of respiratory distress, and a 9-year-old dog presented with a 3-month history of mild abdominal distention. We endoscopically biopsied lesions in both the cases using 5-ALA-PDD. Histopathological examination revealed mesothelioma, and immunohistochemical staining was positive for calretinin. Both patients were treated with carboplatin. The cat died of respiratory failure. Although, the dog's condition improved 21 days after the first chemotherapeutic drug administration, the dog died on day 684 owing to cardiac-related issues. 5-ALA-PDD is thus, safe and feasible for the diagnosis of MM in veterinary medicine.

Clinical presentation, treatment and outcome of canine malignant mesothelioma: A retrospective study of 34 cases.

Canine malignant mesothelioma (CMM) is a rare and aggressive tumour associated with a poor prognosis. Limited information is available regarding effective treatment options and prognostic factors. The purpose of this retrospective case series was to describe the clinical presentation, treatment and survival in a cohort of dogs with this disease and to investigate possible prognostic factors. Thirty-four dogs were included. Tachypnoea and dyspnoea due to pleural effusion were the most common presenting clinical signs. Twenty-two dogs had a subcutaneous access port placed and 25 dogs were treated with intracavitary and/or intravenous chemotherapy. The main protocols used were single-agent 5-FU (n = 14) and carboplatin single-agent or alternated with mitoxantrone (n = 10). The overall response rate (defined as more than 25% reduction in effusion volume) to chemotherapy treatment was 37% after 3-weeks and 24% after 15-weeks. The median survival time (MST) for all dogs was 195 days (95% CI 53-324). MST was 234 days for dogs receiving chemotherapy and 29 days for dogs not receiving chemotherapy. The 1-year survival rate was 22% for all dogs. Treatment with chemotherapy was the only significant prognostic factor associated with survival (p = .001). Further studies are needed to determine the optimal treatment approach for malignant mesothelioma in dogs. Nevertheless, effusion recurrence should be expected and the prognosis for these patients in the long-term is poor.

Histological comparison of malignant epithelioid mesothelioma in young and adult cattle.

The histology and immunohistochemistry of pleomorphic and conventional epithelioid mesotheliomas were examined. The former was detected in two young calves aged 2 and 4 months and was characterized by pleomorphic and atypical cells with decreased expression of cytokeratin 7 (CK7). In contrast, the latter was found in a 31-month-old heifer, consisting of tumor cells uniform in size and shape with CK7 expression in nearly all cells. Production of collagen by tumor cells was demonstrated in both histological types, and was considered to be characteristic of bovine epithelioid mesothelioma. Pleomorphic mesothelioma is far more pleomorphic and mitotically active than conventional mesothelioma, and its normal counterpart may be immature mesothelial cells with high proliferation potential, which exist in fetal life and early calfhood.

Feline mesothelioma: case report and review of cytologic, immunocytochemical, histopathologic, and immunohistochemical findings.

Mesotheliomas are uncommon neoplasms that arise from mesothelial cells in either the abdominal or thoracic cavities and are rarely diagnosed in cats. A 10-y-old spayed female domestic shorthair cat was presented to the Louisiana State University oncology service for evaluation of a large amount of abdominal effusion. Abdominal ultrasound identified a large mesenteric mass with numerous ill-defined nodules. An abdominocentesis was performed with cytologic and immunocytochemical findings consistent with a neoplastic effusion, with large clusters of epithelioid cells that exhibited strong cytoplasmic expression of pancytokeratin, vimentin, and Wilms tumor 1 antigens. Further testing was declined, and meloxicam was prescribed until the cat died 23 d after initial presentation. Upon postmortem examination, the omentum was contracted into a firm mass adhered to multiple organs and accompanied by numerous small white nodules throughout the abdominal cavity. On histopathology and immunohistochemistry, neoplastic cells were found throughout the abdominal cavity; 60-95% exhibited moderate-to-strong cytoplasmic immunoreactivity for cytokeratin, vimentin, and Wilms tumor 1 protein. The final diagnosis was an epithelioid mesothelioma. Our case illustrates the utility of cytology, immunocytochemistry, and its relation to histology and immunohistochemistry. We also reviewed the reported cases of feline mesothelioma.

Cardiovascular images: constrictive pericarditis and tricavitary effusion in a dog with pericardial mesothelioma.

This report describes the transthoracic echocardiographic findings and computed tomography features of a 12-year-old West Highland white terrier with constrictive pericarditis (CP) secondary to pericardial mesothelioma. Although pericardial mesothelioma is well described in dogs, its association with CP in the canine population is not as widely reported. In this clinical case, a multidisciplinary imaging approach was helpful to identify anatomical and hemodynamic abnormalities that allowed for a diagnosis of CP.

Intestinal-peritoneal Coelioscopy for the Diagnosis of a Mesothelioma in a Pet Chicken.

An adult female chicken, from a small backyard flock, was presented to the Ontario Veterinary College Avian and Exotics Service for evaluation of dyspnea and recurrent ascites. An antemortem diagnostic evaluation included a coelomocentesis, coelomic ultrasound, and a coelioscopy procedure. A sample of the fluid collected during the coelomocentesis was submitted for analysis and was determined to be a nonspecific modified proteinaceous transudate. The coelomic ultrasound examination identified numerous coalescing fluid-filled and solid nodules throughout the coelom. However, no site of origin of the nodules could be identified. A coelioscopy of the intestinal-peritoneal cavity was performed by a ventral midline approach, and biopsies collected during the procedure were submitted for histologic examination. The pathologic diagnosis of the biopsy samples was a disseminated neoplasia, presumptively coelomic adenocarcinoma. The chicken received palliative treatment which included periodic coelomocentesis, meloxicam, antibiotics, and deslorelin following the diagnosis of a disseminated neoplasia. Three months following initial presentation the patient was euthanatized. A postmortem examination with histopathology confirmed the tissue biopsy results of coelomic neoplasia. Further immunohistochemistry supported mesothelioma as the definitive diagnosis. This case documents the usefulness of intestinal-peritoneal coelioscopy in identifying neoplasia as the cause of ascites in a pet chicken as well as describing the clinical features and progression of a mesothelioma in this species.