Embolized mesothelial cells within mediastinal lymph nodes of three dogs with idiopathic haemorrhagic pericardial effusion

Outcome of dogs treated with chemotherapy for mesothelioma: A retrospective clinical study on 40 cases and a literature review

Mesothelioma is an uncommon cancer in dogs for which there is no established standard of care. Chemotherapy is often suggested despite no definitive proof of efficacy. The aim of this study was to evaluate the impact of chemotherapy on survival of dogs with mesothelioma. A retrospective multicentric study was carried out. To be included, dogs needed to present an evocative clinical evolution and a morphological diagnosis of mesothelioma. Exclusion of other cause of effusion and complete clinical follow-up were also required. Fourty dogs were included, 27 received chemotherapy (group 1) and 13 did not (group 2). Groups were heterogeneous regarding the proportion of animals undergoing surgery as part of their treatment (16 in group 1, 2 in group 2; p = .016) and homogeneous otherwise. Univariate analysis showed that dogs from group 1 survived significantly longer than dogs from group 2 (MST: 366 vs. 74 days; p < .001). Complete resolution of effusion after the first chemotherapy administration positively correlated with survival in group 1 (MST: 415 vs. 160 days; p < .01). All other variable tested had no significant impact on survival in univariate analysis, but dogs undergoing surgery and dogs having serous membranes' modification at medical imaging tended to survive longer. Multivariate analysis confirmed that chemotherapy was the sole variable independently associated with survival in our study (odds ratio 5.57-6.12; p < .01).

Pathological Findings of Canine Idiopathic Pericarditis and Pericardial Mesotheliomas: Correlation with Clinical and Survival Data

Idiopathic pericarditis (IP) and pericardial mesothelioma (PM) are causes of pericardial effusion in dogs. Pericardiectomy can be a definitive treatment in the case of idiopathic pericardial effusion or a short-term intervention for mesothelioma. The aim of the present study was to investigate which histopathologic parameters are correlated with clinical outcomes in a cohort of dogs that underwent pericardiectomy. The histopathological findings of 22 IPs and 5 PMs were compared with clinical and survival data and the immunohistochemical characterization of immune cells (CD3, CD79α, Iba1). In IP, the mesothelium was lost in 20 cases, reactive in 9, atypical in 3, and mesothelial papillary hyperplasia (MPH) was observed in 4 cases. Numerous macrophages were found in both IPs and PMs especially at the superficial layer of the pericardium. T lymphocytes were observed in mild to moderate numbers and were more numerous than B lymphocytes in both IPs and PMs. MPH was correlated with the quantity of lymphoplasmacytic infiltrate in the superficial layer, inversely related to the thickness of the pericardium, and associated with a longer overall survival. Pericardial fibrosis was present in 19 out of 22 IPs and in all mesotheliomas and was correlated with increased time from initial presentation and pericardiectomy and lymphoplasmacytic infiltrate in the deep zone. Pericardial thickness was correlated with the amount of lymphoplasmacytic and macrophagic infiltrate in the deep zone. Mesothelioma was associated with an increased number of pericardiocentesis procedures before pericardiectomy and with the presence of macrophages in the superficial pericardial layer, edema, fibrin, and hemorrhage. Disease-free interval and overall survival were significantly shorter in patients with mesothelioma compared with IP.

Multicentric Benign Epithelial Inclusions in a Free-ranging Risso's Dolphin (Grampus griseus)

This report describes the histological and immunohistochemical features of multicentric, benign, epithelial inclusions (BEIs) in a free-ranging, adult, female Risso's dolphin (Grampus griseus). The differential diagnoses included ectopic hamartomatous epithelial inclusions, non-Müllerian choristoma, Müllerian choristoma and low-grade metastatic carcinoma/mesothelioma. The most likely diagnosis of such BEIs was multicentric, embolic, reactive mesothelium, as suggested by cytomorphological and immunophenotypical features of the BEIs, the occurrence of focal pleural rupture and the immunophenotype of the pleural mesothelium. The former represents a pathological condition not previously reported in a marine mammal species, rarely described in animals, and relatively infrequently recognized in man.

Nanoparticles and Pop-off Technique for Electron Microscopy

Because of the size of the nanoparticles, their detection and exact anatomical localization in tissue samples are very difficult. Consequently, suitable methods are needed to prove their presence, especially co-localized to histological lesions. Therefore, the aim of this study was to investigate whether nanoparticles were detectable in specimens after reprocessing samples from glass slides using the pop-off technique. Tissue slides containing agglomerates of titanium dioxide nanoparticles already visible on a light microscopic level and amorphous silicium dioxide (SiO2) particles not observable in tissue slides were reprocessed. Furthermore, cytospots of bronchoalveolar lavage acquired from rats that previously inhaled carbon nanotubes were used. After reprocessing the samples, they were investigated using transmission electron microscopy. In all the reprocessed samples, the respective nanoparticles were detectable. Even the light microscopically invisible amorphous SiO2 particles were observed as electron dense structures. Titanium and silicium were additionally confirmed in the respective nanoparticles by energy-dispersive X-ray spectroscopy (EDX). In summary, the pop-off technique represents a fast and easy way to detect nanoparticles in histological sections. This enables further characterization of these particles by additional techniques such as EDX, and their direct correlation with light microscopic lesions at exactly the same location is investigated.

Embolised mesothelial cells in a tracheobronchial lymph node associated with idiopathic chylopericardium in a dog

A 5·5-year-old male castrated Bernese mountain dog presented with respiratory difficulties and was diagnosed with haemorrhagic pericardial effusion which transformed into chylopericardium. Thoracic duct ligation and subtotal pericardiectomy in combination with biopsy of an enlarged tracheobronchial lymph node were performed. Multiple clusters of mesothelial cell emboli were observed in the subcapsular sinus of the lymph node. No causative agent for the pericardial effusion could be identified, suggesting that this is a case of mesothelial cell embolisation associated with idiopathic -chylopericardium in a dog.

Epithelial and pancreatic choristoma in bovine lymph nodes

Lymph nodes from 186 cows were evaluated as part of a bovine tuberculosis eradication programme. The mediastinal lymph nodes of 13 animals contained atypical structures. In 12 cases (6.45%) these consisted of multiple epithelial structures and, in one case, of pancreatic-like tissue. Immunohistochemistry (IHC) revealed that the epithelial structures were consistent with respiratory epithelium and with ectopic pancreatic tissue, respectively. To the best of our knowledge these are the first histological and immunohistochemical descriptions of epithelial and pancreatic choristomas in bovine lymph nodes.

Epithelioid cells in mediastinal lymph nodes of cattle without cancer

Epithelioid cells are found in lymph nodes in cases of metastatic carcinoma; however, epithelioid cells with benign features have also been discovered incidentally in lymph nodes. Epithelioid cells were observed in mediastinal lymph nodes of cattle without cancer during routine diagnostic necropsy. To explain this finding, the authors evaluated the prevalence and histopathologic, immunohistochemical, and ultrastructural features retrospectively using mediastinal lymph nodes from 110 cattle and found that 66 of the lymph nodes contained epithelioid cells. In all 66 nodes, most of the epithelioid cells were individual or aggregated in nodal sinuses; in 21 nodes, some epithelioid cells formed tubular structures. The individual and aggregated epithelioid cells were mostly considered to be mesothelial in origin by immunohistochemical and ultrastructural examination; presumably, they entered the lymph nodes via lymphatic vessels, because they were found in afferent lymphatic vessels and nodal sinuses. Although the presence of epithelioid cells in lymph nodes prompts suspicion of metastatic carcinoma, the epithelioid cells in these bovine lymph nodes did not disrupt nodal architecture, lacked atypia or mitotic figures, and did not invade nodal parenchyma.

Cardiac lymphoma and pericardial effusion in dogs: 12 cases (1994-2004)

OBJECTIVE

To determine clinical characteristics and clinicopathologic findings, including results of pericardial fluid analysis, and determine the outcome associated with pericardial effusion caused by cardiac lymphoma in dogs.

DESIGN

Retrospective case series.

ANIMALS

12 dogs.

PROCEDURE

Medical records of affected dogs were reviewed for echocardiographic findings, radiographic findings, results of pericardial fluid analysis, clinicopathologic findings, treatment protocols, and outcomes.

RESULTS

Pericardial effusion was detected by echocardiography in all 12 dogs, and lymphoma was detected by cytologic examination of the effusion (11/12 dogs) or histologic examination of pericardium (3/12). Large-breed dogs were overrepresented; median weight was 40.5 kg (89.1 lb). Most hematologic and biochemical changes were mild and non-specific. Survival time for dogs treated with combination chemotherapeutic agents was 157 days and for dogs that did not receive chemotherapy survival time was 22 days. This difference was not significant, but several dogs had long-term survival.

CONCLUSIONS AND CLINICAL RELEVANCE

Cardiac lymphoma is an uncommon cause of pericardial effusion, and results suggest that cardiac lymphoma does not always warrant the poor prognosis of other stage V, substage b lymphomas.

Development of pericardial mesothelioma in golden retrievers with a long-term history of idiopathic haemorrhagic pericardial effusion

This report describes the development of pericardial mesothelioma in five golden retrievers with a long-term history of idiopathic haemorrhagic pericardial effusion (IHPE). These five dogs were treated with repeated pericardiocentesis for recurrent episodes of pericardial fluid accumulation; other than IHPE, all potential causes of this fluid accumulation were ruled out by the results of diagnostic imaging and cytology and bacterial or fungal culture of fluid obtained during pericardiocentesis. In three dogs that eventually underwent pericardiectomy, neoplastic lesions were not detected in any organs or tissues within the thoracic cavity during the surgical procedure, and the surgical biopsies were consistent with IHPE. In one of the three dogs, however, cytology of recurrent thoracic effusion revealed clusters of neoplastic mesothelial cells from 1 month after surgical intervention until death. The clinical course of the disease ranged from 30 to 54 months between the first visit and death, and on post-mortem examination pericardial mesothelioma was diagnosed in all five dogs. The clinical observations, together with the breed and age of the affected animals, suggested that the five dogs initially suffered from IHPE, which was then followed by the development of pericardial mesothelioma. It is possible that IHPE is associated with the development of pericardial mesothelioma in golden retrievers through a chronic inflammatory process.