Perirenal pseudocysts in 26 cats

Urinary Tract Trauma in Cats: Stabilisation, Diagnosis and Management

PRACTICAL RELEVANCE

Traumatic injury of the urinary tract may be caused by external accidental trauma or due to iatrogenic injury (typically as a result of catheterisation procedures). Thorough patient assessment and careful attention to patient stabilisation are essential, with diagnosis and surgical repair delayed until the patient is stable, if necessary. Treatment depends on the location and severity of the trauma. If diagnosed and treated promptly, the chance of survival of a patient without other concurrent injuries is good.

CLINICAL CHALLENGES

Following accidental trauma, at the initial presentation urinary tract injury can be overshadowed by other injuries, but if left undiagnosed or untreated it can lead to serious morbidity and potentially mortality. Many of the surgical techniques described for management of urinary tract trauma can be associated with complications, and so comprehensive communication with the owners is necessary.

PATIENT GROUP

The main population affected by urinary tract trauma is young, adult male cats, owing to their roaming behaviour, as well as their anatomy and the resulting increased risk of urethral obstruction and its associated management.

AIMS

This article aims to serve as a guide to all veterinarians who treat cats for the diagnosis and management of urinary tract trauma in cats.

EVIDENCE BASE

This review summarises the current knowledge available from a number of original articles and textbook chapters in the literature that cover all aspects of feline urinary tract trauma, and is supported by the authors' own clinical experience.

Case series: Pleural effusion caused by urinary ultrafiltrate in two cats without evidence of urinary obstruction, trauma, or simultaneous perinephric pseudocysts

Objectives

To describe the diagnostic techniques, surgical treatments, and outcomes of two cats with recurrent pleural transudate caused by urinary ultrafiltrate.

Animals

Two cats without evidence of trauma, urinary tract obstruction, or concurrent perinephric pseudocysts that were evaluated and treated for recurrent pleural transudate caused by urinary ultrafiltrate.

Study design

Short case series.

Methods

Multiphase contrast CT scan revealed leakage of contrast media from the kidneys bilaterally into the retroperitoneal spaces in both cats. Renal scintigraphy performed in one cat revealed progressive accumulation of 99mTc diethylenetriamine penta-acetic acid (Tc-DTPA) in the pleural space. Exploratory laparotomy localized the leakage of fluid to renal capsular defects bilaterally in both cats. The retroperitoneum was incised bilaterally to promote fluid drainage into the peritoneum, and nephropexies were performed.

Results

One cat had long-term survival with recurrent, though decreasing volumes of, pleural effusion. The second cat was euthanized 16 days postoperatively for progressive renal disease.

Conclusion

The diagnosis of spontaneous urinary ultrafiltrate accumulation in the pleural space of cats without evidence of trauma, urinary tract obstruction, or concurrent perinephric pseudocysts has not previously been reported. The surgical correction described reduced but did not completely eliminate the rate of pleural effusion accumulation.

Perioperative characteristics, histologic diagnosis, complications, and outcomes of dogs undergoing percutaneous drainage, sclerotherapy or surgical management of intrarenal cystic lesions: 18 dogs (2004-2021)

BACKGROUND

Canine intrarenal cystic lesions (ICLs) are infrequently reported in the veterinary literature. Several treatment options have been described including cyst fenestration (partial nephrectomy/deroofing) +/- omentalization, sclerotherapy using alcohol as a sclerosing agent, percutaneous cyst drainage (PCD), and ureteronephrectomy. Information regarding presenting clinical signs, physical examination findings, histologic diagnosis and outcomes of dogs with ICLs treated by different methods is limited. Medical records of 11 institutions were retrospectively reviewed to identify dogs that underwent PCD, sclerotherapy, surgical deroofing +/- omentalization, or ureteronephrectomy for management of ICLs from 2004 to 2021. Six weeks postoperative/post-procedural follow-up was required. Cases suspected to represent malignancy on preoperative imaging were excluded. The study objective was to provide information regarding perioperative characteristics, complications, and outcomes of dogs undergoing treatment of ICLs.

RESULTS

Eighteen dogs were included, with 24 ICLs treated. Ten had bilateral. There were 15 males and 3 females, with crossbreeds predominating. PCD, sclerotherapy, deroofing and ureteronephrectomy were performed in 5 (5 ICLs treated), 7 (11 ICLs), 6 (6), and 7 (7) dogs, respectively, with 5 dogs undergoing > 1 treatment. Seven dogs experienced 8 complications, with requirement for additional intervention commonest. PCD, sclerotherapy and deroofing resulted in ICL resolution in 0/5, 3/11 and 3/6 treated ICLs, respectively. Histopathology identified renal cysts (RCs) in 7/13 dogs with histopathology available and neoplasia in 6/13 (4 malignant, 2 benign). Of 5 dogs diagnosed histopathologically with neoplasia, cytology of cystic fluid failed to identify neoplastic cells. Among 7 dogs with histologically confirmed RCs, 4 had concurrent ICLs in ipsilateral/contralateral kidney, compared with 2/6 dogs with histologically confirmed neoplasia.

CONCLUSIONS

Benign and neoplastic ICLs were approximately equally common and cystic fluid cytology failed to differentiate the 2. Among renal-sparing treatments, deroofing most commonly resulted in ICL resolution. Presence of concurrent ICLs in ipsilateral/contralateral kidney does not appear reliable in differentiating benign from malignant ICLs.

Feline abdominal ultrasonography: what's normal? what's abnormal? The kidneys and perinephric space

PRACTICAL RELEVANCE

Abdominal ultrasound plays a vital role in the diagnostic work-up of many cats presenting to general and specialist practitioners. Ultrasound examination of the kidneys and perinephric space can provide important information on several conditions including chronic renal disease, hydronephrosis and perinephric pseudocyst formation.

CLINICAL CHALLENGES

Despite ultrasonography being a commonly used modality, many practitioners are not comfortable performing an ultrasound examination or interpreting the resulting images. Even for the experienced ultrasonographer, differentiating between incidental findings, such as a medullary rim sign, and pathological changes can be challenging.

AIM

This review, part of an occasional series on feline abdominal ultrasonography, discusses ultrasonographic examination of the normal and diseased kidney and perinephric space. Aimed at general practitioners who wish to improve their knowledge of and confidence in feline abdominal ultrasound, this review is accompanied by high-resolution images and videos available online as supplementary material. A subsequent article will address ultrasonography of the collecting system including the renal pelvis and urinary bladder.

EQUIPMENT

Ultrasound facilities are readily available to most practitioners, although use of ultrasonography as a diagnostic tool is highly dependent on operator experience.

EVIDENCE BASE

Information provided in this article is drawn from the published literature and the author's own clinical experience.

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.

Laparoscopic resection of bilateral perinephric pseudocyst in a pediatric feline patient

Case summary

A 6-month-old male domestic shorthair cat presenting with abdominal distension and an acute history of renal azotemia was diagnosed with bilateral perinephric pseudocysts and International Renal Interest Society (IRIS) grade 3 acute kidney injury. Ultrasound-guided drainage of the cysts was performed initially; bilateral subtotal resection of the perinephric pseudocysts was later performed using laparoscopy as a more long-term solution. There was no regrowth or reformation of the perinephric pseudocysts 1 year after the procedure, and the cat remained in IRIS stage 2 chronic kidney disease 1 year postoperatively.

Relevance and novel information

Compared with traditional surgical approaches, laparoscopic resection of perinephric pseudocysts provides a less invasive approach. Bilateral perinephric pseudocyst in a pediatric feline patient (and associated treatment) has not previously been documented in the literature.

A, Giglio C, Wiecheteck F, Oliveira M, Godoy C, Hora A. Ressecção de cisto e abscesso renais por laparoscopia em um cão

Cistos renais podem formar-se em qualquer parte do néfron e dos ductos coletores. Alguns são hereditários, originando-se durante a organogênese, e outros se desenvolvem no tecido renal normal, depois que os rins estão completamente formados. No presente relato, descreve-se a ressecção de cisto e abscesso renais, por cirurgia laparoscópica em um cão. Para o acesso, foram utilizados três portais, dois de 10mm de diâmetro e um de 5mm, dispostos na parede abdominal lateral direita e, num segundo momento, na parede abdominal lateral esquerda. Conclui-se, portanto, que a técnica laparoscópica com três portais permite a realização de ressecção de cisto e abscesso renais em cães, sem a ocorrência de recidivas em curto prazo.

Ultrasonography of the feline kidney: Technique, anatomy and changes associated with disease

PRACTICAL RELEVANCE

Ultrasonography is an important tool for the detection of kidney disorders, which are among the most common health problems suffered by cats. It is more accurate than radiography for this purpose and is considered to be the reference modality for imaging the feline kidney, providing excellent visualisation of renal size, shape and internal architecture. Compared with more advanced imaging modalities, such as computed tomography or magnetic resonance imaging, ultrasonography is more accessible, less expensive, does not require general anaesthesia and allows real-time procedures to be performed.

CLINICAL CHALLENGES

On ultrasound examination, focal or multifocal disorders may be readily identified, but diffuse changes are more challenging. B-mode ultrasonography is of limited use for differentiating between benign and malignant focal lesions. However, based on the presence and pattern of vascularity as an indicator of malignancy, contrast-enhanced ultrasonography allows distinction between benign and malignant focal renal lesions.

AUDIENCE

This review provides a framework for the ultrasonographic approach to feline renal and perirenal disorders for the general practitioner.

EVIDENCE BASE

Drawing on current literature relating to ultrasonographic examination of feline kidneys, the aim is to summarise ultrasonographic technique, anatomy and changes associated with renal and perirenal diseases.

Cistolitectomia e ressecção de cisto renal por laparoscopia em uma cadela com aderências intraperitoneais: relato de caso

No presente relato descreve-se a remoção de urólitos vesicais, bem como o tratamento de um cisto renal por cirurgia laparoscópica em um cão com aderências intraperitoneais. Para o acesso foram utilizados três portais, dois de 10mm e um de 5mm, dispostos na linha média ventral e nas paredes abdominal direita e esquerda. Após a remoção das litíases, realizou-se sutura intracorpórea da parede vesical em duas camadas. O cisto renal direito foi drenado e sua cápsula extirpada. Ocorreu a perda temporária de um urólito na cavidade abdominal e sua posterior recuperação pela cirurgia laparoscópica. O paciente não apresentou recidiva da doença pelo período mínimo de 14 meses. A cirurgia laparoscópica mostrou-se eficaz na terapêutica de ambas as patologias, sem a necessidade de alteração do posicionamento dos portais.

Bilateral laparoscopic subtotal perinephric pseudocyst resection in a cat

A 17-year-old castrated male domestic shorthair cat was diagnosed with bilateral perinephric pseudocysts (PNPs). Bilateral subtotal resection of the PNPs was performed via a laparoscopic approach. There was no regrowth or reformation of the PNPs after the procedure and the cat's serum concentration of creatinine remained stable for 6 months after surgery. Laparoscopic bilateral subtotal resection of PNPs appears to have been an effective treatment option in this cat with the advantages of being minimally invasive and requiring only a brief hospital stay.

Unilateral improvement in glomerular filtration rate after permanent drainage of a perinephric pseudocyst in a cat

A 12-year-old, 6 kg, castrated male Siamese-cross cat was referred for investigation of an abdominal mass. The cat was found to have a left perinephric pseudocyst (PNP), accompanied by azotemia, with a small right kidney detected on ultrasound. Glomerular filtration rate (GFR) was determined by renal scintigraphy and was found to be low, with the left kidney contributing 64% of the total GFR. Percutaneous ultrasound-guided drainage of the PNP did not improve the GFR, and fluid reaccumulated within a short period of time. Laparoscopic fenestration of the cyst capsule was performed to allow for permanent drainage. The PNP did not recur, renal values progressively improved, and 8 months after the capsulotomy the GFR of the left kidney had increased by 50%, while renal function remained static on the right side.

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.

Unilateral perinephric pseudocyst secondary to hydronephrosis in a C57BL/6J mouse

A 9-month-old C57BL/6J mouse had progressive abdominal distension over a 1-week period, and a distended left renal capsule was discovered at postmortem examination. Incision of the capsule showed a tan, cloudy fluid that separated the renal capsule and the remnant left kidney. Microscopically, the capsule was significantly separated from the renal parenchyma by clear space and necrotic cellular debris. The majority of the lining of the renal capsule was composed of fibrous connective tissue and lacked an epithelial lining, consistent with a subcapsular perinephric pseudocyst. In addition, attached to intermittent portions of the renal capsule were thin rims of compressed cortical tissue lined by transitional epithelium. The finding of remnant cortical tissue lined by transitional epithelium is consistent with severe hydronephrosis and indicates that the hydronephrosis preceded the formation of the perinephric pseudocyst. To our knowledge, this is the first case report to characterize a perinephric pseudocyst secondary to severe hydronephrosis in a mouse.

Retroperitoneal perirenal pseudocyst in a Massese breed ram

The macroscopic and microscopic features of a retroperitoneal perirenal pseudocyst in a 12-month-old ram without impairment of renal function are described. In humans and animals, uriniferous pseudocysts may be of traumatic origin, resulting from rupture of kidney, renal pelvis, or ureter, or congenital. Lymphatic pseudocysts may develop secondary to inflammatory obstruction of the hilar lymphatics after perinephritis or renal transplantation. In this case, histologic characteristics of the pseudocyst wall were suggestive of development from the parietal peritoneal layer encapsulating the kidney. This is the first case of retroperitoneal perirenal pseudocyst in a sheep.

Perirenal pyelocaliceal diverticulum in an infant cat

A 3-month-old female tortoise-shell cat showing azotemia died with a marked swollen abdomen. Necropsy revealed a huge perirenal cyst (8.5 x 6.0 x 4.5 cm) on the ventral aspect of the right kidney. The cyst was filled with the pellucid yellow fluid with a smell of urine. The lumen was connected with irregularly dilated renal pelvis by a narrow channel passing through the renal parenchyma. The cyst was lined by epithelial cells and its wall was consisted of collagen fibers and smooth muscle cells as that of the renal pelvis and ureter. Renal parenchyma adjacent to the channel showed interstitial infiltration of the lymphoid cells. The cyst was a diverticulum of the renal pelvis due to an impaired development.

Post-traumatic paraureteral urinoma in a cat

A retroperitoneal urinoma (uriniferous pseudocyst) was diagnosed in a domestic shorthair cat exhibiting a sublumbar swelling two weeks after a road traffic accident. Plain radiography revealed a soft tissue opacity in the left retroperitoneal space. Intravenous urography and fine-needle aspiration were diagnostic. Contrast was seen pooling in the dilated ipsilateral renal pelvis and proximal ureter. Fluid aspirated from the retroperitoneal space had a creatinine level five times that of serum. Surgical drainage followed by nephrectomy and omentalisation of the pseudocyst was curative.