April’s Case of the Month - 2024

Sonographer: Mallory Repellin DVM

Patient information:

Age: 12 years, 10 months
Gender: Female Spayed
Breed: DLH
Species: Feline

History:

Patient is continuing to show clinical signs of inappetence for the past month. At her initial examination, she was prescribed mirataz to improve her appetite. The owners reported improvement in eating but this has not been consistent throughout the month. Owner has been offering various diet to entice appetite. Patient has been vomiting frequently, consisting mostly of food and liquid. She has been experiencing liquid diarrhea without the presence of blood or melena. Owners have reported seeing her frequently in the litter box but she does not always appear to be producing adequate urine. Her overall demeanor at home has changed, she stopped grooming herself, will vocalize frequently, and is no longer interested in normal interactions like playing with the owners.

Ultrasonographic findings:

Kidneys:

Normal size (Lt/Rt = 4.0/4.0 cm) and mildly scalloped shape with decreased corticomedullary dimensions. Significant pyelectasia (4.4 mm) visualized within the left renal pelvis, scan pyelectasia noted within the right.

There is hyperechoic perirenal fat appreciated adjacent to the caudal pole of the left kidney which continues caudally along the route of the ureter. The left ureter can be imaged leading to an irregular, rounded, hypoechoic, vascular structure concerning for a ureteral mass near the trigone of the urinary bladder measuring approximately 1.5 x 2.4 cm (sagittal), 1.7 x 2.7 cm (transverse).

Pancreas:

Normal size (0.5 cm depth), shape, and mildly hypoechoic echogenicity with coarse echotexture.

Intestines:

Diffuse small intestinal loops have prominent muscularis bowel layering, normal to increased thickness, and normal motility. No loss of layering, obstruction, or masses seen.

Lymph Nodes:

Multiple mesenteric lymph nodes are prominent (max depth 0.4 cm) with rounded shape having heterogenous hypoechoic echogenicity.

Abdominal ultrasound interpretation:

Caudal abdominal Mass -DDX: associated with left ureter, uterine stump, other

Intestines - the findings are mild - DDX: inflammatory bowel disease/food intolerance vs. infiltrative neoplasia (small-cell lymphosarcoma vs. mast cell tumor) vs. parasitism (cestode) vs. dry FIP vs. fungal (histoplasmosis). Inflammatory bowel disease in cats can be chronic and long-standing but in many cases will transition into small-cell lymphosarcoma and it is not possible with ultrasound alone to determine in this case whether the disease is benign or infiltrative.

Pyelectasia DDX:

a) IV fluid administration
b) Pyelonephritis and ureteritis
c) Increased diuresis caused by renal insufficiency or other condition
d) Toxin
e) Infectious (leptospira, etc)
f) Post-renal obstruction / Bladder distention
g) Diuresis

Kidneys - the findings are mild - DDX:
a) Chronic nonspecific change - (chronic glomerulonephritis vs. amyloidosis), chronic interstitial nephritis, chronic nephritis. In cats, the loss of corticomedullary distinction is not unusual with chronic renal disease as interstitial fibrosis in the medulla renders its echogenicity similar to that of the cortex.
b) Acute renal failure/Nephritis (infectious, GN, toxic, etc.) vs. Acute-on-Chronic renal failure
c) Lymphosarcoma
d) Pyelonephritis

A hyperechoic irregular mass in the region of the left proximal ureter, there is significant inflammation surrounding the mass.

Sagittal view of the same suspected left ureteral mass.

Sections of jejunum which demonstrate increased thickness and prominent muscularis wall layering.

Transverse image of the left kidney demonstrating moderate pyelectasia, secondary to suspected left ureteral mass.

Recommendations:

Referral of this patient for advanced imaging (CT scan) and to discuss possible surgical options for resection/biopsy are highly recommended.

Fine-needle biopsy with cytology may be considered, injectable immobilizing sedation is required to consider this procedure.

Addition of pain medications to current therapy protocol is highly recommended for this patient.

Additional tests:

CT scan:

· Thorax: Throughout the pulmonary parenchyma, there are several round to ovoid soft tissue dense structures along the periphery of the lung lobes (best example: series 11 image 240, ~4 mm in diameter).

· The cardiovascular structures, pleural space, and mediastinal structures are within normal limits. Thoracic spondylosis deformans is present.

· Abdomen and Pelvis: The left renal pelvis is distended, up to 1.2 cm. The proximal left ureter is also fluid distended, up to 3 mm. The ureter becomes collapsed at the mid to distal aspect of the ureter and courses into a mass-like lesion at the level of the caudal abdomen. The left ureter is seen caudal to this mass and enters the urinary bladder.

· Within the caudal abdomen, there is a peripherally contrast enhancing, lobulated mass that appears confluent with the adjacent colonic wall on the sagittal reconstructions. The mass is in contact with the adjacent urinary bladder wall and the left ureter is not visible in this region. Additionally, there is the impression of narrowing of the colonic lumen at this level. The mass is in contact with the adjacent caudal abdominal aorta and the aortic trifurcation.

· Associated with the rectum in the pelvic canal, there is a lobulated, heterogeneously contrast enhancing circumferential mass, up to 1 cm in thickness. There are tendril-like heterogeneous contrast enhancing structures emanating from this lesion with one coursing into the region of the musculature adjacent to the body of the right ilium and another coursing towards the wall of the urinary bladder lumen at the level of the trigone. No intra-luminal urinary bladder mass is seen. The lumen of the rectum is narrowed at this site.

· Few colic lymph nodes are thickened and exhibit inhomogeneous contrast enhancement, up to 5.5 mm (example: series 14 image 233). There is amorphous, inhomogeneous contrast enhancing soft tissue density at the ICJ and partially surrounding the cecum (~2 cm L x ~1 cm W).

· The muscularis layer of multiple jejunal segments is subjectively thickened.

· The right kidney cortex is irregular.

· The spleen exhibits heterogeneous contrast enhancement with no distinct lesion present.

· The liver, adrenal glands, pancreas, and included bony structures are within normal limits.

Conclusions:

· Pulmonary nodules are consistent with metastasis.

· Circumferential lesion associated with the rectum with tendril-like regional extensions and narrowing of the lumen. The primary differential is neoplasia, such as carcinoma.

· Concurrent lesion in the caudal abdomen is suspected to arise from the colonic wall and may invade into or surround the left ureter. The possibility this is a left ureteral wall lesion that invades into the colonic wall is not excluded. The primary differential is neoplasia, such as carcinoma.

· Colic lymph node enlargement; differentials include a reactive process or spread of neoplasia.

· Structure in the region of the ICJ is thought to represent an enlarged lymph node; reactive process or spread of neoplasia. The possibility of a concurrent cecal wall lesion cannot be entirely excluded.

· Left hydronephrosis and hydroureter is consistent with an obstruction secondary to the caudal abdominal mass. Irregular right kidney is likely secondary to chronic kidney changes.

· Heterogeneous contrast enhancement of the spleen; differentials include variation of normal, or infiltrative disease (benign or malignant- malignant is thought less likely).

· Muscularis thickening of multiple jejunal segments; differentials include enteritis, inflammatory bowel disease, or small cell lymphoma.

Cytology (based off US-guided fine-needle aspirate of caudal abdominal mass)

· Digital Cytology- INTERPRETATION: Epithelial proliferation with moderate atypia, mixed inflammation, and necrosis; consistent with a carcinoma

· COMMENTS: The mass exfoliated well and yielded high numbers of moderately atypical epithelial cells admixed with inflammation and necrosis. These findings are consistent with a carcinoma, and an intestinal adenocarcinoma is a likely consideration given the provided history. Biopsy with histopathology may be indicated for further characterization.

· CYTOPATHOLOGIC DESCRIPTION: 2 slides are evaluated. The slides are of mild to moderate cellularity over a background of proteinaceous tissue fluid and mild to moderate peripheral blood. The cells consist of moderately atypical epithelial cells noted in small to large clusters and seen individually. The cells have oval nuclei, coarse chromatin, prominent and occasionally multiple nucleoli, and a scant amount of basophilic cytoplasm. Moderate anisocytosis and anisokaryosis are observed. Few binucleated and multinucleated cells are seen. Inflammatory cells are present which include nondegenerate and deteriorated neutrophils with lesser numbers of macrophages and small lymphocytes. Cellular degeneration is evident as well.

Discussion:

Feline gastrointestinal adenocarcinomas are the most common nonhematopoietic gastrointestinal tumors in cats. They are highly malignant tumors causing intestinal obstruction due to the annular, stenosing nature to their growth. Current literature is largely based on surveys of pathology records. Therefore, a retrospective study was conducted to evaluate clinical course and prognosis with surgical excision of the tumor. In published reports feline gastrointestinal adenocarcinoma represented 20-35% of gastrointestinal neoplasia in the cat; the average age was greater than ten years; and there was a greater incidence in Siamese. The small intestine accounted for 70% of cases. In this retrospective study, cats usually had a long history of non-specific gastrointestinal disease; weight loss and vomiting were the most common signs. Abdominal radiographs demonstrate intestinal obstruction, and an abdominal mass is often palpable. With intestinal resection and anastomosis, median survival time was 2.5 months (range: 0-24 months).

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1680855/

Patient outcome:

Based on cytologic diagnosis of a carcinoma, the associated prognosis after surgery and her already declining health status, her owners made the difficult decision to relieve her suffering through humane euthanasia.

A very special ‘thank you’ to Dr. Jordan from District Veterinary Hospital- Brookland for sharing patient details and allowing for an in-depth discussion of their patient.