Pulmonary carcinosarcoma in a cat

Pathological and immunohistochemical characterization of pancreatic carcinoma in cats

The aim of this study was to characterize the pathological and immunohistochemical aspects of pancreatic carcinoma in cats, through a retrospective study. From January 2010 to December 2021, 1,908 cat necropsies were performed, in which 20 cases of exocrine pancreatic neoplasia were diagnosed (1.04%). Affected cats were mature adults and seniors, except for one 1-year-old cat. In 11 cases the neoplasm was a soft, focal nodule on the left (8/11) or right (3/11) lobe. In nine cases there were multifocal nodules throughout the pancreatic parenchyma. The size of the single masses ranged from 2 to 12 cm, and the multifocal masses from 0.5 to 2 cm. The most frequent tumour type was acinar carcinoma (11/20), followed by ductal carcinoma (8/20), undifferentiated carcinoma (1/20) and carcinosarcoma (1/20). On immunohistochemical evaluation, all the neoplasms were remarkably reactive to pancytokeratin antibody. The ductal carcinomas were strongly reactive for cytokeratins 7 and 20, which proved to be a good marker for pancreatic ductal carcinoma in cats. The main form of metastasis was abdominal carcinomatosis, with a marked invasion of blood and lymphatic vessels by neoplastic cells. Our findings reinforce the fact that pancreatic carcinoma should be rated highly in the differential diagnosis in mature adult and senior cats with abdominal masses, ascites and/or jaundice.

Feline uterine carcinosarcoma infiltrated with osteoclast-like giant cells

A 12-year-old female Himalayan cat underwent an ovariohysterectomy to remove an intra-abdominal mass. Histologic examination using immunohistochemical staining revealed that the mass was comprised of epithelial and mesenchymal components. Within the lesion, multinucleated giant cells (MGCs) were observed diffusely. MGCs were positive for vimentin and Iba-1 and negative for cytokeratin AE1/AE3 and CD204. In addition, MGCs were negative for Ki-67, indicating nonneoplastic cells. Osteoclast-like MGC (OLMGC) phenotype with tartrate-resistant acid phosphatase positivity was also seen. These findings suggested that the uterine tumor was carcinosarcoma with OLMGCs. Uterine tumors in humans, such as leiomyosarcoma and carcinosarcoma, with OLMGC infiltration, are well-known pathologic entities; however, they are rare in animals and to our knowledge, have not been previously reported in cats.

Primary pulmonary diffuse large B-cell lymphoma associated with feline leukaemia virus infection in a young cat

Case summary

A 4-year-old castrated male domestic shorthair cat with a continuous cough was brought to a private veterinary clinic for detailed examination. Radiography of the thoracic cavity revealed a severe radiopaque region in the caudal lobe of the right lung. At 108 days after the initial visit, CT showed a mass of 27 × 23 × 18 mm in the caudal lobe of the right lung. At that time, no abnormalities in other organs except for the lung were detected on CT and peripheral blood and blood biochemistry tests. The mass in the caudal lobe of the right lung was resected by lobectomy; it had a white surface and was firm. Histopathologically, the mass was non-encapsulated, showing an unclear boundary with surrounding tissues. The mass comprised large, round or polygonal neoplastic cells arranged in a diffuse pattern. Immunohistochemically, neoplastic cells were diffusely positive for CD20, feline leukaemia virus (FeLV) p27 and FeLV glycoprotein 70 but negative for CD3, CD204 and E-cadherin. Based on these findings, diffuse large B-cell lymphoma associated with FeLV infection was diagnosed. Although the cat showed no clinical signs of gastrointestinal or respiratory injury, a routine ultrasonography revealed thickening in the jejunum wall 196 days after lobectomy, and subsequent fine-needle aspiration examination confirmed high-grade lymphoma.

Relevance and novel information

This is the first report of primary pulmonary diffuse large B-cell lymphoma associated with FeLV infection in a young cat.

Pulmonary Sarcomatoid Carcinoma Associated with Arterial Thromboembolism in a Cat

A 14-year-old, neutered male domestic shorthair cat presented for acute monoparesis with physical exam findings and biochemical data supportive of a distal arterial thromboembolism. Thoracic radiographs revealed an alveolar pattern in the right middle lung lobe and multifocal nodules in other lung lobes. A pulmonary mass was found on necropsy, which was composed of both carcinomatous and sarcomatous components, confirmed with cytokeratin and vimentin immunohistochemistry. Using the World Health Organization classification scheme for mixed pulmonary tumors, this tumor would be characterized as a pleomorphic squamous cell carcinoma under the umbrella term of pulmonary sarcomatoid carcinoma. The World Health Organization classification of mixed pulmonary tumors and its application to previously reported mixed pulmonary tumors in companion animals is discussed. This is the first reported case of this tumor type in a cat, as well as the first report of this tumor type associated with an arterial thromboembolism in any veterinary species.

Bilateral Thyroid Carcinosarcoma in a Cat

A neutered female domestic shorthaired cat was presented for a rapidly growing left cervical mass and a 6-month history of primary hyperthyroidism. Cytological examination of the mass was consistent with a sarcoma. Due to poor clinical response the cat was humanely destroyed and a post-mortem examination was performed. This revealed a markedly enlarged, irregularly shaped left thyroid gland with signs of infiltration of the trachea. The contralateral (right) thyroid was also moderately enlarged and irregularly shaped. Histopathological examination of the cervical masses indicated bilateral thyroid carcinosarcomas, evidenced by positive immunohistochemical labelling for vimentin, pan-cytokeratin and thyroid transcription factor-1 of the appropriate cell populations. The cat also had a concurrent pulmonary adenocarcinoma (papillary-lepidic type), unrelated to the thyroid neoplasm. Thyroid carcinosarcoma is an uncommonly recorded canine and human neoplasm and this is the first case of this entity to be reported in a cat.

A Comparative Review of Mixed Mammary Tumors in Mammals

Mixed tumors are characterized by the histological identification of two or more cell types. Commonly, a mixture of epithelial and myoepithelial cells is included in abundant stroma, which can consist of myxoid, chondroid or bony matrices. Spontaneously arising mixed tumors are rare lesions in the human breast but are common in human salivary glands and canine mammary glands. Subtle histopathological characteristics and overlapping attributes of malignant lesions with other benign lesions can lead to a diagnostic challenge. Mixed tumors can present as benign or malignant. While malignant mixed tumors are quite rare in the human breast they have a poor prognosis. Benign mixed mammary tumors occur more frequently in female dogs than in humans and are usually associated with a good prognosis. This review will provide a comprehensive overview of mixed mammary tumors, across various mammalian species.

Uterine carcinosarcoma (malignant mixed Müllerian tumor): case report in a goat and literature review

Carcinosarcomas are biphasic malignant tumors composed of 2 distinct neoplastic cell populations, epithelial cells and mesenchymal cells. A 13-y-old, female, mixed-breed goat was presented with a 1-wk history of anuria and lethargy. Transabdominal ultrasonography showed an irregular and heterogeneous structure in the region of the bladder and uterus and changes in the echogenicity of both kidneys. Given the poor prognosis, euthanasia was elected. Autopsy revealed a large mass within the uterine cervix and confirmed the changes in the urinary tract. Histopathology and immunohistochemistry revealed a mixed, anti-cytokeratin AE1/AE3-positive epithelial, and vimentin-positive mesenchymal neoplasm consistent with a homologous carcinosarcoma, also called malignant mixed Müllerian tumor, with areas of double-labeling. We highlight the complexity of the diagnosis of uterine neoplasms in domestic animals and in goats in particular.

Canine Carcinosarcomas in the Head

Four cases of neoplasms in the heads of old dogs were studied. All the dogs showed both carcinomatous and sarcomatous malignant components in an admixed growing pattern. Histologic analysis of the tumors showed that the carcinomatous cells resembled squamous cell carcinoma in all dogs except one, where an adenoid arrangement of the neoplastic cells was also observed. The sarcomatous component showed osteoid matrix produced by pleomorphic poorly differentiated cells, which is regarded as a typical feature of osteosarcomas. Immunohistochemical analysis demonstrated that the components were positive only for cytokeratin (carcinomatous component) or vimentin (sarcomatous component). This observation led us to classify the neoplasms as true carcinosarcomas, thus providing evidence of a new preferential location for this unusual tumor in dog.

Carcinosarcoma of the biliary system in a cat

A 12-year-old, mixed-breed domestic cat was diagnosed with a multicystic hepatic mass via ultrasonographic examination and computer tomography scan. The tumor associated with the left medial liver lobe, and connected by a thin stalk to the hilar region, was surgically removed. The mass was firm, encapsulated, mottled white to red black, multinodular, and cystic. Histologic diagnosis was carcinosarcoma supported by positive immunohistochemistry for cytokeratins and vimentin of atypical neoplastic cell populations. On the basis of morphology, the origin was considered to be in the biliary tract. Biliary carcinosarcoma is a rare neoplasm that occurs in people. The epidemiology and risk factors have not yet been determined, and the prognosis is poor except for cases in which curative resection is performed.

Pancreatic carcinosarcoma in a cat

A 10-year-old female American shorthair cat was presented for evaluation of weight loss. An intra-abdominal mass was found on ultrasonography and laparotomy was performed. The mass was located in the left uterine horn and further masses were found in the pancreas, greater omentum and diaphragm. Microscopical examination revealed that the pancreatic mass had epithelial and mesenchymal components, which on immunohistochemistry expressed cytokeratin and vimentin, respectively. In addition, some spindle cells expressed vimentin and E-cadherin, which might suggest epithelial to mesenchymal transition. In contrast, the uterine, omental and diaphragmatic masses had only mesenchymal composition. The pancreatic lesion is proposed to be a primary carcinosarcoma with metastasis of only the mesenchymal component to distant sites. This the first report of pancreatic carcinosarcoma in a cat.

Sarcomatoid carcinoma in the lung of an Egyptian fruit bat (Rousettus aegyptiacus)

A sarcomatoid carcinoma was diagnosed in the lung of a 10-year-old captive Egyptian fruit bat (Rousettus aegyptiacus). Both carcinomatous and sarcomatous cytologic phenotypes were identified histologically. Cells of both types stained positive for pancytokeratin and S-100. Stromal cells stained positively for muscle actin. No staining for vimentin was noted in either neoplastic or normal internal control tissues. To the authors' knowledge, this is the first report of a pulmonary sarcomatoid carcinoma in a bat, and only the third report of sarcomatoid carcinoma outside the human literature.