Primary renal tumours in cats: 19 cases (1992-1998)

Clinical outcomes in cats with renal carcinoma undergoing nephrectomy: A retrospective study

Renal carcinomas (RC) are uncommonly encountered in feline medicine. Limited information regarding clinical presentation and postoperative outcomes is available. The purpose of this multi-institutional, retrospective study was to describe the presenting features and clinical outcomes of cats with RC undergoing nephrectomy. Thirty-six client-owned cats were included. Medical records from participating institutions were searched to identify cats that had a histopathologic diagnosis of RC and underwent nephrectomy from January 2001 to October 2021. The most common presenting complaints were weight loss (36.1%) and hyporexia (30.6%). Based on preoperative imaging and intraoperative findings, eight cats had suspected metastasis at the time of surgery (22.2%). Twenty-eight cats survived to discharge (77.8%). Median progression free interval (PFI) could not be determined, as only six cats developed suspected recurrence (16.7%) and seven cats developed suspected metastasis (19.4%). The all-cause median survival time (MST) was 203 days (95% confidence interval [CI]: 84, 1379 days). When cases that died prior to discharge were excluded, MST increased to 1217 days (95% CI: 127, 1641 days). One-year, two-year, and three-year survival rates were all 40.4%. Neither renal tumour histologic subtype nor the presence of preoperative azotemia, anaemia, erythrocytosis, haematuria, or suspected metastasis at diagnosis were found to influence survival. For cats surviving to discharge, prolonged survival times were possible. Further studies are necessary to elucidate other potential prognostic factors, the utility of postoperative adjuvant treatment, and to identify cats at-risk of mortality in the perioperative period.

Unilateral primary carcinoma of the kidney with central nervous system invasion and vertebral lysis in a cat

Case summary

A young adult female spayed domestic shorthair cat presented for acute hindlimb weakness and anorexia with a 1-month history of lethargy, hyporexia and weight loss. A mass was palpable in the caudolateral abdomen and the left hindlimb was diffusely edematous. Abdominal ultrasound showed hydronephrosis of the left kidney with suspected hydroureter and heterogeneous tissue in the dorsal abdomen. CT evaluation confirmed a mass extending from the left kidney through the lumbar musculature with hydronephrosis, aortic attenuation, caudal vena caval thrombosis and lysis of vertebrae 4 and 5. Fine-needle aspiration of the mass suggested squamous cell carcinoma. Owing to clinical deterioration, euthanasia was elected. At necropsy, the left kidney was firmly adhered to the lumbar region with tissue that obliterated the musculature and surrounded the aorta and vena cava. There was hydronephrosis of the left kidney. Histopathologic evaluation of the mass revealed islands of neoplastic epithelial cells separated by fibrous connective tissue and areas of gradual keratinization with rare squamous metaplasia. The histologic diagnosis was invasive carcinoma with desmoplasia and vascular invasion.

Relevance and novel information

Primary carcinomas of the kidney in cats are rare and this report documents a progression of disease not previously reported in cats. This is the second reported case of a primary carcinoma of renal origin with features of squamous cell carcinoma in a cat, and the first with lumbar and vascular invasion. This is also the first use of kidney injury molecule-1 to help investigate tumor differentiation in cats.

Feline sarcomatoid renal cell carcinoma with peritoneal carcinomatosis and effusion

A 9-y-old, castrated male, domestic medium-hair cat diagnosed previously with chronic kidney disease developed anorexia and vomiting. Ultrasonography revealed abdominal effusion and a left renal perihilar mass. Cytologic evaluation of the peritoneal fluid and mass identified atypical epithelioid cells suspected to be of renal epithelial or possible mesothelial origin. Immunohistochemical (IHC) evaluation of a formalin-fixed, paraffin-embedded peritoneal fluid cell block indicated both pancytokeratin and vimentin expression in the atypical epithelioid cell population. With scanning electron microscopic evaluation, similar epithelioid cells lacked the cell-surface microvilli expected of mesothelium, supporting an antemortem diagnosis of probable carcinoma. On postmortem examination, the left kidney was effaced by an infiltrative neoplasm with myriad similar nodules throughout the peritoneum. The neoplasm was composed primarily of polygonal-to-spindle-shaped cells with strong vimentin and weak pancytokeratin cytoplasmic immunolabeling. Further IHC characterization with PAX8, CK18, KIT, napsin A, SMA, desmin, CD18, and claudin 5 was performed. Histologic and IHC findings supported a diagnosis of sarcomatoid renal cell carcinoma with peritoneal carcinomatosis. An in vitro cell culture line of neoplastic cells harvested from the primary tumor was successfully established for future research endeavors.

Renal Crest Proliferative Lesions in Cats with Chronic Kidney Disease

In a histopathological study of the renal crest (RC) of kidneys of cats with chronic kidney disease (CKD), 58/90 (64%) had epithelial proliferation. Of these, 33 cats had hyperplasia of the collecting duct (CD) epithelium (CDH) alone, eight had hyperplasia of the urothelium covering the RC (RCUH), of which one had concurrent abaxial renal pelvic urothelial hyperplasia (UH), and eight had both CDH and RCUH. CDH or RCUH were present in five cats with marked dysplasia of the CD epithelium (CDD) and four cats with invasive carcinomas, which also had epithelial dysplasia. All nine cats with marked dysplasia or neoplasia of the RC also had substantially altered RC contours due to focal haemorrhage, papillary necrosis or fibrosis. Three of the carcinomas had a strong desmoplastic response. In control cats, both urothelial (RC and renal pelvis) and tubular (CD and distal tubular) cells were immunopositive for cytokeratin (CK; AE1/AE3), tubular epithelial cells were positive for vimentin (Vim) and aquaporin 2 (Aq2), while urothelial cells were positive for p63. PAX8 immunolabelling was difficult to validate. CD and UH labelling was similar to control tissue. While urothelial dysplasia had the same immunolabelling pattern as UH and control tissue, CDD was generally immunonegative for Aq2. As immunolabelling of the four carcinomas did not distinguish between tubular and urothelial origin, with three positive for both Vim and p63, all were broadly designated as RC carcinomas. Overall, proliferative epithelial lesions are common in cats with CKD and form a continuum from simple hyperplasia to neoplasia of the urothelium or CD of the RC.

Renal adenocarcinoma associated with hypertrophic osteopathy in a cat

Case summary

A 10-year-old neutered male domestic shorthair cat was diagnosed with renal adenocarcinoma associated with hypertrophic osteopathy. The cat was referred for chronic ambulation difficulties. The physical examination showed a painful thickening of all four limbs, a right cranial abdominal mass and a conjunctival hyperaemia. Radiographic findings were consistent with extensive periosteal new bone formation involving not only the diaphyses of the fore- and hindlimbs, but also of the pelvis, tarsus and carpus. Abdominal ultrasonography and CT revealed a mass within the right kidney and a primary neoplasm was suspected. A ureteronephrectomy of the right kidney was performed and histopathology confirmed the diagnosis of renal adenocarcinoma. Although clinical improvement of the lameness occurred after surgery, no radiographic changes of hypertrophic osteopathy lesions were observed at the 9-month follow-up.

Relevance and novel information

Feline cases of hypertrophic osteopathy are rarely reported in the literature and only a few of them were associated with abdominal neoplastic diseases. To our knowledge, this is the first case of renal adenocarcinoma associated with hypertrophic osteopathy in a cat.

Giant pericardial-occupying compressive primary cardiac hemangiosarcoma in a cat

Hemangioarcoma in the cat is an infrequently diagnosed tumor, and cardiac involvement is rare. We report a previously healthy, 8-year-old, domestic shorthair cat with acute collapse associated with pericardial effusion and cardiac tamponade. Following pericardiocentesis and removal of 15 mL of fluid, the cat improved rapidly. A massive, space-occupying, intrapericardial tumor adhered to and compressing the right atrium and ventricle was detected by echocardiography. Approximately 5 weeks following initial presentation, bicavitary effusion and tachypnea developed, and the cat was euthanized. Necropsy revealed a giant intrapericardial mass adhered to and impinging upon the right heart. Histologic and immunohistochemical examination confirmed hemangiosarcoma with no gross or histologic evidence of metastasis. To the authors' knowledge, this is the first account of a pericardial-occupying, primary feline cardiac hemangiosarcoma resulting in compression of the right heart and cardiac tamponade, Further, this report describes novel clinicopathological relationships between radiographic and echocardiographic findings and gross and microscopic pathology.

Myxosarcoma Associated with the Kidney in a Cat: Case Report

A 12 yr old spayed female domestic shorthair with a history of lethargy, anorexia, and a pendulous abdomen was referred after a cranial abdominal mass was palpated on physical examination. Thoracic radiographs and an abdominal ultrasound revealed a mass associated with the kidney and moderate hemoperitoneum. Exploratory laparotomy revealed abdominal hemorrhage originating from a right renal mass that was adhered to the caudal vena cava. Following a right nephrectomy, histopathology diagnosed the mass as a perirenal/renal myxosarcoma. Based upon thoracic radiographs and abdominal ultrasound, the patient remains disease free at 14 mo postoperatively.

Renin-producing Tumour in the Kidney of a Cat

Clinical and post-mortem examination of an adult neutered male cat with immune-mediated haemolytic anaemia revealed suspected nodules of tumour tissue in the cortex of the right kidney. Cytology and histopathology indicated a malignant renal tumour of undetermined type. Immunohistochemistry confirmed renin production by a proportion of the tumour cells. The lesion may represent a renal adenocarcinoma producing renin or a tumour of juxtaglomerular cells ('reninoma').

Cardiac Leiomyosarcoma in a Cat Presenting for Bilateral Renal Neoplasia

A 10-year-old neutered female domestic longhair cat was presented to a tertiary care veterinary hospital for evaluation of a right renal mass that was identified incidentally on abdominal radiographs and classified further as a sarcoma based on fine needle aspiration cytology. Further diagnostic workup, including ultrasound and cytology, identified a sarcoma in the left kidney. After approximately 1 month of conservative medical management, the clinical condition deteriorated and the cat was humanely destroyed. Post-mortem examination confirmed bilateral renal masses with multifocal infarction and extensive necrosis, and further identified a large mass at the apex of the heart as well as multiple pulmonary nodules. Microscopical examination of the masses identified a population of poorly-differentiated neoplastic spindle cells, consistent with sarcoma. Immunohistochemically, the neoplastic cells expressed smooth muscle actin and muscle-specific actin, but were negative for myoglobin and factor VIII. Phosphotungstic acid-haematoxylin staining was unable to identify cross-striations in the neoplastic cells. Based on these results and the pattern of lesion distribution, the cat was diagnosed with cardiac leiomyosarcoma with pulmonary and bilateral renal metastasis.

Urologic Oncology

Primary renal tumors are an uncommon diagnosis in small animals. Presentation, treatment, and prognosis depend on tumor type. Surgery with or without chemotherapy are the mainstays of treatment. Transitional cell carcinoma is the most common tumor of the urinary system. Clinical signs include hematuria, stranguria, and pollakiuria. Metastatic disease can develop over time within medial iliac lymph nodes, lungs, and vertebrae. Treatment of transitional cell carcinoma centers on chemotherapy with mitoxantrone, vinblastine, or carboplatin. Other agents used with success, include toceranib phosphate and chlorambucil. Interventional surgery, such as stenting and laser ablation, is used in a palliative setting addressing urinary obstruction.

Histopathologic and Immunohistochemistry Findings in Feline Renal Cell Carcinoma

The biological behavior and immunohistochemical features of feline renal cell carcinoma (RCC) have not been well characterized. In the present study, immunohistochemical examinations were performed in 12 feline cases of RCC. The RCC consisted of solid ( n = 2), solid-tubular ( n = 2), tubular ( n = 3), papillary ( n = 2), tubulopapillary ( n = 2), and sarcomatoid ( n = 1) type lesions. Of the cases with RCC, 1 developed metastatic disease and 6 cases had no evidence of recurrence at 80 to 2292 days after surgery. One papillary-type tumor had cuboidal cells with scant cytoplasm and monomorphic nuclei, and the other had pseudostratified columnar cells with abundant cytoplasm. Immunohistochemistry revealed that the tumor cells in most cases were positive for cytokeratin (CK)7, CK20, KIT, and CD10, with the exception of cases of the solid type with clear cytoplasm (solid anaplastic), papillary type with columnar cells, and sarcomatoid types. A small number of tumor cells in the solid anaplastic and in the sarcomatoid types were positive for aquaporin-1. Increased expression of N-cadherin and Twist along with nuclear accumulation of β-catenin were observed in the sarcomatoid type. These results indicated that CK, KIT, and CD10 are relatively strongly expressed in most feline RCC. The solid anaplastic RCC exhibited CD10 expression with the absence of distal tubule marker expression. Although immunohistochemistry profiles were relatively consistent with those described in human RCC, the histopathologic features were different from those seen in humans. Epithelial-mesenchymal transition (EMT) marker expression in the current cases may suggest the involvement of an EMT-like mechanism in the development of sarcomatoid RCC in cats.

Renal cell carcinoma in a cat with polycystic kidney disease undergoing renal transplantation

Case summary

A 10-year-old spayed female American Shorthair cat underwent renal transplantation due to worsening chronic kidney disease secondary to polycystic kidney disease. During transplantation, the right kidney grossly appeared to be more diseased than the left and was firmly adhered to the surrounding tissues. An intraoperative fine-needle aspirate of the right native kidney revealed inflammatory cells but no evidence of neoplasia. To create space for the allograft, a right nephrectomy was performed. Following nephrectomy, the right native kidney was submitted for biopsy. Biopsy results revealed a renal cell carcinoma. Although the cat initially recovered well from surgery, delayed graft function was a concern in the early postoperative period. Significant azotemia persisted and the cat began to have diarrhea. Erythematous skin lesions developed in the perineal and inguinal regions, which were suspected to be secondary to thromboembolic disease based on histopathology. The cat’s clinical status continued to decline with development of signs of sepsis, followed by marked obtundation with uncontrollable seizures. Given the postoperative diagnosis of renal cell carcinoma and the cat’s progressively declining clinical status, humane euthanasia was elected.

Relevance and novel information

This case is the first to document renal cell carcinoma in a cat with polycystic kidney disease. An association of the two diseases has been reported in the human literature, but such a link has yet to be described in veterinary medicine. Given the association reported in the human literature, a plausible relationship between polycystic kidney disease and renal cell carcinoma in cats merits further investigation.

Renal adenocarcinoma-associated erythrocytosis in a cat: clinicopathological features and immunohistochemical results

This report documents a case of secondary inappropriate erythrocytosis in a cat with renal cell adenocarcinoma, its stabilization through manual erythrocytapheresis, and the EPO-immunostaining on the affected kidney. An 11-year-old cat was presented with lethargy, weight loss and polyuria/polydipsia. An abdominal mass was detected upon physical examination. Clinicopathological work-up revealed marked erythrocytosis (HCT value 64.8%), renal azotemia and decreased urine specific gravity (USG). An abdominal ultrasound was performed, localizing the mass in the right kidney. Serum erythropoietin (EPO) was above the reference interval (RI), and the cytology of the mass was indicative of renal carcinoma. Manual erythrocytapheresis was performed in order to stabilize the patient before surgery, improving the cat’s clinical and clinicopathological condition. After nephrectomy, EPO and creatinine concentrations returned within the RI, while the USG markedly increased. Histopathology confirmed the diagnosis of renal adenocarcinoma. Immunohistochemistry with anti-EPO antibody revealed diffuse and strong cytoplasmatic positivity in tumor cells.

[Renal pleomorphic sarcoma in four guinea pigs (Cavia porcellus)]

OBJECTIVE

Renal tumours apparently are rare not only in cats and dogs, but also in guinea pigs and can be difficult to diagnose. The aim of this study is to describe the clinical, pathological and immunohistochemical findings in guinea pigs with renal tumours. Furthermore, the symptoms, diagnostic possibilities and therapy are compared with renal tumours in other small animals, including cats and dogs.

MATERIAL AND METHODS

During a period of 4 years and 4 months the data of guinea pigs that had been presented in the clinic were retrospectively analysed. The analysis comprised guinea pigs that underwent a macroscopical and histopathological postmortem examination, and were diagnosed to have a renal neoplasm.

RESULTS

Four guinea pigs had a renal tumour. The percentage of renal neoplasms in relation to the overall necropsied carcasses and the number of organs originating from guinea pigs was 4.7 % and the percentage of renal neoplasms in relation to the overall diagnosed tumours of the abdominal and pelvic cavities was 30.7 %. Histology and immunohistochemistry revealed the presence of renal pleomorphic sarcomas in all four cases. In two of the four guinea pigs, the classical triad, as described for cats and dogs with renal tumours (weight loss, abdominal mass and haematuria), was observed. During clinical examination, a prominent, apparently painful abdominal mass in the region of the kidneys was palpable in all four cases. Applying radiography, the suspected diagnosis of a mass in the area of the kidney was confirmed in three cases, and in two animals the renal origin of the masses was determined by ultrasound examination.

CONCLUSION AND CLINICAL RELEVANCE

Because a renal neoplasm is a pain-inducing disease with a high risk of metastases in domestic animals, a prompt nephrectomy should be performed when azotaemia is absent.

DIAGNOSIS AND TREATMENT OF A UNILATERAL RENAL CYSTADENOMA IN AN AFRICAN LION (PANTHERA LEO)

A renal tubular cystadenoma was diagnosed in a 14-yr-old male African lion (Panthera leo). During a routine health evaluation, a left renal mass was identified via physical examination, radiographs, and abdominal ultrasonography. The mass was 30 × 15 cm in size and had a thin capsule with central hypoechoic fluid, suggestive of a perirenal cyst. An exploratory celiotomy with partial nephrectomy was performed without complications. Histologically, the tumor was characterized by a thick fibrous capsule surrounding multiple, variable-sized cysts that markedly compressed the adjacent fibrotic and atrophied renal cortex. Immunohistochemical labeling for Aquaporin-1 and Tamm-Horsfall protein was consistent with a renal tubular cystadenoma of proximal tubule origin. Renal cystadenomas are an uncommon benign epithelial neoplasm. There are only two documented case reports in domestic cats. This report represents the first documentation, to the authors' knowledge, of a renal cystadenoma in a lion.

Renal oncocytoma in a cat with chronic renal failure

CASE SUMMARY

A 9-year-old male neutered domestic shorthair cat presented with anorexia. Ultrasonography showed an irregularly shaped hypoechoic mass in the cranial pole of the right kidney. Ultrasound-guided fine-needle aspiration of the renal mass was performed. Cytology revealed moderate cellularity smears composed of epithelial cell clusters, which consisted of an exclusive population of oncocytic cells seen in sheets and papillary clusters along with abundant single cells. A moderate-to-abundant amount of densely stained granular cytoplasm with round nuclei and indistinct nucleoli was seen. The cytological diagnosis was renal oncocytic neoplasm. CT and surgical resection revealed a firm tan mass in the right kidney. A final diagnosis of renal oncocytoma was made on the basis of histology, immunohistochemical staining profile (positive for cytokeratin, and negative for chromogranin A, neuron-specific enolase and vimentin) of neoplastic cells, together with the electronic microscopy results.

RELEVANCE AND NOVEL INFORMATION

We believe that this is the first report of the cytological features of feline renal oncocytoma.

Renal transitional cell carcinoma with bilateral ocular metastasis in a cat

Case summary A 4-year-old, spayed female, domestic shorthair cat was presented for evaluation due to a 4 day history of inappetence and lethargy. Physical examination revealed mild dehydration and blindness of the left eye. Abnormal imaging findings included a well-margined soft tissue mass with irregular central cavity located in the dorsal aspect of the caudal lung lobe. Cytological examination of the mass revealed chronic inflammation with hemorrhage. Tests for parasitic and fungal diseases were negative. Ophthalmic examination 17 days after the cat was initially presented revealed severe diffuse pathology of both retinas. Left renomegaly was noted 22 days after the initial presentation, and cytological examination of samples obtained from the right vitreous, left kidney and the pulmonary mass yielded atypical epithelial cells exhibiting malignant changes. Post-mortem examination following euthanasia revealed renal transitional cell carcinoma with metastasis to both eyes, lungs and skeletal muscle. Immunohistochemical evaluation of the neoplastic cells in the eye revealed moderate cytoplasmic reactivity for CK7. CK20 immunohistochemistry was negative.

Relevance and novel information To the best of our knowledge, this is the first report of renal transitional cell carcinoma with ocular metastasis in a cat. In addition, this report describes immunohistochemistry results of transitional cell carcinoma in a cat using CK7 and CK20.

TREATMENT OF RENAL CARCINOMA IN A BINTURONG (ARCTICTIS BINTURONG) WITH NEPHRECTOMY AND A TYROSINE KINASE INHIBITOR

A 13-yr-old female binturong ( Arctictis binturong ) presented with a 1 wk history of decreased appetite. The animal was thin, with hypercalcemia (calcium 12.2 mg/dl). A right renal mass was identified on ultrasound and removed via nephrectomy. Histopathology indicated a renal adenocarcinoma. Treatment with toceranib phosphate, a tyrosine-kinase inhibitor, was initiated and well tolerated by the animal. Four months after initial diagnosis radiographs indicated metastases to the lungs and the animal was euthanized. Necropsy revealed disseminated adenocarcinoma. Although treatment did not prevent metastasis, it was minimally invasive and well tolerated by the animal with minimal side effects. Review of records at the institution revealed that the cause of death for the primary case's dam and sire was disseminated renal carcinoma. These cases suggest that there may be a hereditary component to development of renal neoplasia in binturongs. Renal carcinoma should be considered an aggressive neoplasia in binturongs with a poor prognosis.

A Retrospective Study of Visceral and Nonvisceral Hemangiosarcoma and Hemangiomas in Domestic Animals

Cases of hemangiosarcoma submitted to the Colorado State University Veterinary Diagnostic Laboratory during a 6-year period were reviewed. Visceral hemangiosarcomas represent less than 2% of canine specimens submitted for histologic examination and nonvisceral hemangiosarcoma less than 1%. Most nonvisceral hemangiosarcomas of dogs occur in skin. Hemangiosarcomas are less common in cats and usually occur in skin. They are also rare in other animal species. Animals with nonvisceral hemangiosarcomas are usually mature; dogs and cats average 10 years of age. The tumors develop in many different locations, and there is no sex predilection. A wide variety of dog breeds are affected, but Italian greyhounds, greyhounds, and whippets are overrepresented. Clinical outcomes of 76 cases of nonvisceral hemangiosarcomas in dogs and cats were obtained from submitting veterinarians. Completeness of excision of a tumor is the most important factor that can be used in predicting clinical outcome for an affected dog or cat. In all cases in which the animals were clinically normal for at least 1 year after surgical removal of a nonvisceral hemangiosarcoma, the margins were reported to be free of neoplastic cells. Degree of differentiation, mitotic rate, size of tumor, and presence or absence of epidermal ulceration, mast cells, or solar elastosis did not correlate with clinical outcome.

Renal leiomyosarcoma in a cat

Renal leiomyosarcoma was diagnosed in a 10-year-old Domestic Shorthair cat with a 3-year history of clinically managed, chronic renal disease. Sudden death was preceded by a brief episode of mental dullness and confusion. At postmortem examination, the gross appearance of the left kidney was suggestive of hydronephrosis, and a nephrolith was present in the contralateral kidney. However, histology revealed an infiltrative, poorly differentiated, spindle cell sarcoma bordering the grossly cavitated area. Neoplastic cells were immunoreactive for vimentin and smooth muscle actin, which led to a diagnosis of renal leiomyosarcoma; neoplastic cells were not immunoreactive for desmin. Leiomyosarcoma arising in the kidney is a rare occurrence in humans and an even rarer occurrence in veterinary medicine with no prior cases being reported in cats in the English literature. The macroscopic appearance of the tumor at postmortem examination was misleadingly suggestive of hydronephrosis as a result of the large cavitation and may be similar to particularly unusual cases of renal leiomyosarcomas in humans that have a cystic or cavitated appearance.

Histological and immunohistochemical characterization of feline renal cell carcinoma: a case series

Four feline renal cell carcinomas (RCCs) were examined using histopathological and immunohistochemical procedures. Specimens were classified by predominant histological pattern according to WHO criteria. A panel of antibodies including β-catenin, C-KIT, VEGF and VEGF-R2 and double immunostaining for vimentin/cytokeratin and for E-cadherin/CD10 was selected to characterize the tumors. Neoplasms were classified as tubular (3/4) and papillary (1/4). Neoplastic epithelial cells were cytokeratin, vimentin, E-cadherin, VEGF-R2 positive and C-KIT negative; 3 cases were β-catenin positive, whereas only 2 tumors were CD10 and VEGF positive. No correlation with histotype was evident. Our results confirm the low frequency of RCCs in cats and suggest a histological pattern similar to canine RCCs. In contrast, a peculiar immunohistochemical profile different from both canine and human RCCs is identified.

The human Bosniak model applied to a cat with renal cystadenoma. A classification to differentiate benign and malignant cystic renal masses via computed tomography and ultrasound

A 13-year-old domestic shorthair cat was presented with weight loss and azotemia. Abdominal ultrasound revealed a large cystic space- occupying lesion with multiple septae in the left kidney. A core needle biopsy yielded a renal cystadenoma originating from the epithelial cells. This report describes the clinical, ultrasonographic and computed tomographic features and the growth progression of a renal cystadenoma. We describe the first attempt to apply the human Bosniak classification to a cat with renal cystic neoplasia to differentiate between benign and malignant lesions. Cystadenoma should be a differential diagnosis in cases of renal cystic space-occupying lesions. Other differentials, imaging features to differentiate benign and malignant lesions and the risk of malignant transformation will be discussed.

Immunohistochemical Characterization of a Renal Nephroblastoma in a Trp53-mutant and Prolyl Isomerase 1-deficient Mouse

A nephroblastoma is a tumor arising from metanephric blastema occurring in childhood. Among laboratory rodents, nephroblastoma has been frequently reported in rats, but it remains exceedingly rare in mice. The present work describes a nephroblastoma in a young mouse homozygous for the specific Trp53 R172H point mutation coupled with targeted deletion of the Pin1 gene. The affected kidney was effaced by a biphasic tumor with an epithelial component arranged in tubules surrounded by nests of blastemal cells. Immunohistochemically, the neoplasm was diffusely positive for Wilms’ tumor antigen. The epithelial component expressed markers of renal tubular differentiation including wide-spectrum cytokeratin, E-cadherin and folate-binding protein. Furthermore, the neoplasm exhibited a high proliferative index and diffuse nucleocytoplasmic β-catenin expression. Based on histological and immunohistochemical features, a diagnosis of nephroblastoma potentially associated with Trp53 loss and oncogenic β-catenin activation has been proposed.

Unilateral squamous cell carcinoma of the renal pelvis with hydronephrosis in a cat

A 4-year-old female neutered domestic shorthair cat was presented for evaluation of gradual onset of lethargy and anorexia. Physical examination revealed moderate abdominal distension. Investigations performed included complete blood count, serum biochemistry, urinalysis, pyelocentesis, abdominal fluid analysis, abdominal ultrasonography and exploratory celiotomy. Nephrectomy was performed on the hydronephrotic kidney and a sample of the omentum was also taken, as it was grossly abnormal. No other abnormalities were found in the remainder of the abdominal organs. Findings were consistent with unilateral hydronephrosis and squamous cell carcinoma of the renal pelvis with abdominal carcinomatosis. The patient was given supportive treatment while the results of the biopsies from the renal tissue and the omentum were pending. The patient deteriorated a short time after surgical intervention and was euthanased. This is the first report of a squamous cell carcinoma arising from the renal pelvis in a cat. A comparison with the disease presentation in humans is also discussed.

Feline acute kidney injury: 1. Pathophysiology, etiology and etiology-specific management considerations

PRACTICAL RELEVANCE

Acute kidney injury (AKI) is a frequently recognized disease process in cats that requires immediate and aggressive intervention. A thorough understanding of the pathophysiologic processes underlying AKI and familiarity with the most common etiologies are essential for providing the most effective and timely therapy. Possessing this knowledge will also allow a more accurate prognosis to be given, and afford the best chance of a favorable outcome.

CLINICAL CHALLENGES

Feline patients often present with vague signs of AKI, which may delay treatment and adversely affect the prognosis. Their response to injury and treatment is often different to that of other species.

AUDIENCE

This two-part review article is directed at small animal practitioners as well as specialists. Part 1 reviews mechanisms underlying AKI in the cat, as well as etiologies and treatments related to some specific causes of AKI.

EVIDENCE BASE

The veterinary literature is limited with regards to the pathophysiology of AKI unique to the cat. However, there are numerous feline studies evaluating causes of AKI.

Sarcomatoid renal cell carcinoma with scant epithelial components in an Angora cat

CASE HISTORY

A 6-year-old, neutered, female Angora cat presented with a history of lethargy and anorexia for 2 months and a clinically palpable and gradually enlarging, solid mass in the abdominal cavity extending from the last costal arch to the pelvic cavity.

CLINICAL FINDINGS

Examination of the cat revealed jaundice, dehydration and hypothermia. Haematological manifestations included lymphopenia and substantial decrease in haematocrit value. Biochemical analysis of the blood revealed hypoglycaemia, three-fold elevated blood urea nitrogen values, increased level of serum aspartate aminotransferase and increased total bilirubin while the creatinine level was normal. Ultrasonographic examination of the abdomen showed a disrupted and large hypoechoic area around the left kidney. The cat was anaesthetised and the left kidney was removed, but the cat died following surgery.

PATHOLOGICAL FINDINGS

On post-mortem examination, the left kidney was markedly enlarged and both the cortical and medullary parenchyma were replaced by confluent, multilobulated, pale tan-white, firm nodular masses protruding above the capsular surface. Metastasis was not observed. Cytological examination revealed a population of spindle-shaped cells of variable size, with abundant coarse chromatin and occasionally prominent nucleoli. Initial sections of the kidney were indicative of undifferentiated sarcoma confirmed by immunohistochemistry revealing vimentin-positive and cytokeratin-negative results in all tumour tissues. Additional sections showed very small amounts of both cytokeratin-positive and vimentin-positive areas.

DIAGNOSIS

Sarcomatoid renal cell carcinoma (SRCC) with scant epithelial components originating from left kidney.

CLINICAL RELEVANCE

Clinical and pathological features were similar to those of human SRCC, even though there was no evidence of metastases. Immunohistochemistry for vimentin and cytokeratin may be useful for definitive diagnosis of renal cell carcinoma with sarcomatoid differentiation, although staining of sections from several different parts of the tumour may be necessary. When a primary renal tumour is presented, SRCC should be considered as this diagnosis may influence treatment protocols and the clinical outcome.

Renal transitional-cell carcinoma in two cats with chronic kidney disease

Two 12-year-old cats were diagnosed with chronic kidney disease (CKD) based on physical examination, clinicopathologic data and, in one case, abdominal ultrasound findings. Approximately 1 year after the initial diagnosis of CKD both cats developed renal transitional cell carcinoma (TCC) — bilateral in one cat. Based on post-mortem examination, one cat had no evidence of metastasis and the other had metastasis to the large intestine, heart and lungs. This is the first report of de novo bilateral renal TCC in a cat, as well as the first report of renal TCC developing in cats with previous history of confirmed CKD.

Hypertrophic osteopathy associated with a renal adenoma in a cat

Hypertrophic osteopathy is a hyperostotic syndrome of the appendicular skeleton that is most commonly associated with intrathoracic neoplasia or inflammation. The condition is rarely associated with intra-abdominal lesions. The majority of cases have occurred in dogs and human beings, with fewer cases reported in cats, horses, and other species. A 15-year-old male neutered Domestic Shorthair cat presented for swollen limbs and difficulty in ambulation. Radiographs and gross postmortem revealed severe periosteal hyperostosis of the diaphysis and metaphysis of all 4 limbs, including the humerus, radius, ulna, carpi, metacarpi, femur, tibia, tarsi, metatarsi, and phalanges. The axial skeleton was spared. Hyperostotic lesions were characterized microscopically by lamellar bony trabeculae separated by adipocytes and scant hematopoietic tissue. In several areas, fibrovascular connective tissue, woven bone, and islands of cartilage were also present. A 2.5 cm × 2.5 cm perirenal neoplasm compressed the left kidney and adrenal gland. This mass consisted of well-differentiated tubules of cuboidal epithelial cells and was most consistent with a renal tubular adenoma, because mitotic figures were rare, and no distant metastases were found. Thoracic pathology was absent. Hyperostosis was consistent with hypertrophic osteopathy secondary to the renal adenoma. The pathogenesis of hypertrophic osteopathy is uncertain, but predominant theories point to increased peripheral circulation and angiogenesis as a key initiating event. Recent literature highlights the potential role of vascular endothelial growth factor and platelet-derived growth factor in the human condition. The mechanism by which this renal adenoma caused hypertrophic osteopathy is unknown.

Resolution of renal adenocarcinoma-induced secondary inappropriate polycythaemia after nephrectomy in two cats

Two cases of secondary, inappropriate polycythaemia caused by renal adenocarcinoma in domestic shorthair cats, are described. The cats were 9 and 12 years old and both were presented because of generalised seizures presumably due to hyperviscosity. Both cats had a markedly increased haematocrit (0.770 and 0.632 l/l) and thrombocytosis (744×109/l and 926×109/l). An abdominal ultrasound revealed a mass in the cranial pole of one kidney in both cats. Serum erythropoietin (EPO) concentration was within the reference interval (RI) in both cats but was inappropriately high considering the markedly increased haematocrit. The cats were initially stabilised and managed by multiple phlebotomies and intravenous fluid therapy and underwent nephrectomy of the affected kidney later on. Both the polycythaemia and thrombocytosis resolved following surgery. Postoperative serum EPO concentration, measured in one cat, decreased markedly. Histopathology of the affected kidneys confirmed a diagnosis of renal adenocarcinoma. Both cats were stable for an 8-month follow-up period; however, one cat had developed a stable chronic kidney disease (CKD), while the other was represented 8 months postoperatively due to dyspnoea, and had radiographic evidence of lung metastasis, presumably because of the spread of the original renal tumour and was euthanased. Initial stabilisation of polycythaemic cats should include multiple phlebotomies. Nephrectomy should be considered in cats with secondary, inappropriate, renal adenocarcinoma-related polycythaemia when only one kidney is affected by the tumour, and provided that the other kidney's function is satisfactory. Nephrectomy should be expected to resolve the polycythaemia and lead to normalisation of serum EPO concentration.

Transitional cell carcinoma forming a perirenal cyst in a cat

An eight-year-old, neutered male Burmese cat presented with five days vomiting and anorexia. Physical examination, clinical pathology and diagnostic imaging findings suggested a perirenal pseudocyst. After partial resection of the perirenal capsule clinical signs temporarily resolved, but the cat was euthanased 34 days postoperatively as a result of seizures and recurrence of vomiting. Postoperative histopathology showed neoplastic transitional cells within and lining the resected perirenal capsule; a diagnosis of transitional cell carcinoma was confirmed post-mortem. To the authors' knowledge, this is the first report of this presentation of transitional cell carcinoma. Transitional cell carcinoma should be a differential diagnosis for the aetiology of perirenal pseudocyst.

Diagnostic approach to hematuria in dogs and cats

Hematuria indicates the presence of urogenital disease in dogs and cats. Persistent hematuria (macroscopic or microscopic) should be evaluated to determine the source of bleeding and the underlying cause so that appropriate treatment can be recommended. Results of the history and physical examination often help to localize disease to the urinary tract (either upper or lower) or genital tract. Additional diagnostic evaluation, including laboratory testing(eg, urinalysis, urine culture), diagnostic imaging (eg, abdominal radiographs, ultrasound), and collection of tissues for cytologic or histopathologic evaluation, may be needed to identify the underlying cause. If a thorough evaluation fails to reveal the source or cause of hematuria, exploratory celiotomy should be considered,especially if idiopathic renal hematuria is possible.