Case Study

Lymphoma with amyloid deposition in a 15 year old FS DSH cat

A 15-year-old FS DSH with was presented for decreased appetite and lethargy with a history of hypoalbuminemia, hypomagnesemia, and hypocalcemia. On physical examination weight loss, pyrexia, dehydration, icterus, and a grade III/VI heart murmur were present. Abnormalities on CBC and serum biochemistry were leukocytosis with a mature neutrophilia, monocytosis, non-regenerative anemia, azotemia, hyperphosphatemia, and hypocalcemia.

DX

Malignant B cell neoplasm deriving from an abdominal lymph node with multifocal amyloid deposition.

Sonographic Differential Diagnosis

Aggressive mesenteric and abdominal lymph node masses suggestive for lymphoproliferative neoplasia, likely round cell origin such as lymphoma. Minor potential for granulomatous disease with lymphatic proliferation. Infiltrated distal ileum is suggestive for concurrent intestinal neoplasia such as lymphoma or complicated inflammatory disease or F.I.P. Hypoalbuminemia is likely due to protein losing enteropathy or emerging hepatic failure from potential infiltrative liver disease.

Image Interpretation

A 3.8 x 2.9 cm, mixed hyperechoic and hypoechoic mass was noted in the left cranial abdomen (Image 1). Hyperechoic reactive fat is noted from the 1 to 5 o’clock position around the mass. This mass is likely of lymph node origin given that a large artery was present in the middle of the mass, which is suggestive of mesenteric artery (Video 1). Thickened small intestine adjacent to lymph node mass in the area of the ileocolic junction (Image 2). The mass followed by the sonographer in its entirety is actually composed of a cluster of infiltrated lymph nodes with semi-complex heterogeneous parenchymal changes with loss of structural detail and perinodal echogenic fat suggestive for the presence of an inflammatory component (Video 2). The distal small intestine in the mid-field presented a thickened muscularis with areas of loss of detail located adjacent to the lymph node mass to the left in this view (Video 3). Surrounding reactive fat was noted throughout the intestinal tract. Note the loss of mural detail in this portion of intestine suggestive for complicated transmural inflammatory disease or neoplastic infiltrates or potential feline infectious peritonitis. A separate mildly complex and mildly vascular sublumbar lymph node mass was also present with similar echotexture to the mesenteric lymph node mass. The urinary bladder is noted to the right of the screen (Video 4).

Outcome

The patient had been treated with I.V. fluids, Pepcid, pain medication, KCl, Baytril, and amoxicillin. After responding to treatment, the patient was discharged only to re-present for vomiting, lethargy,progressive weight loss, and acute change in mentation. Physical examination found that the original abdominal mass was enlarged, now felt irregular, and encompassed the majority the patient’s abdomen. A new mass was also discovered in the caudal abdomen on palpation. Abnormalities on recheck blood work were leukocytosis, neutrophilia with 1+ toxic changes and resolved monocytosis, Hct 15% (normocytic, normochromic non-regenerative anemia,) TP 7.2 g/dl, azotemia, BUN 126 mg/dl, creatinine 6.7 g/dl, Phos 14.3 mg/dl, and Ca 7.3. Follow-up ultrasound revealed persistence of the ileocecocolic mass, which is likely of lymph node origin. It now measured 4.8 x 1.97 cm. A minor amount of free fluid was noted at this point likely owing to lymphatic strangulation at the mesenteric root. Note: The clinical renal profile was caused by ureterolithiasis of the left ureter and secondary left hydronephrosis. The heart murmur was a simple physiological flow turbulence. The pathologist also felt that amyloid was likely in the kidneys, creating the urolithiasis and subsequent acute change in mentation from severe azotemia.

Comments

June 2011 SonoPath Case Of The Month: What grows in the mesenteric root of our feline patients? Let the sampling begin! Tomie Timon RDMS of Animal Sounds Mobile Imaging, Eugene, Oregon with Dr. Sharon Blouin of Corvallis Cat Care bring us Annie, a case of mesenteric root pathology with a complex, interesting, and surprising sampling outcome. Mesenteric nodal pathology can have quite a personality at times. Special thanks to Tomie Timon RDMS of Animal Sounds Mobile Veterinary Imaging, Eugene, Oregon and Dr. Sharon Blouin and staff at Corvallis Cat Care for submitting and managing this interesting case.

Clinical Differential Diagnosis

Icterus – prehepatic (IMHA, mycoplasmosis, toxins), post-hepatic (cholecystitis/rupture/bile duct obstruction secondary to neoplasia, pancreatitis, duodenal IBD/neoplasia/foreign body). Azotemia – chronic kidney disease, pyelonephritis. Heart murmur – cardiomyopathy, valve insufficiency, physiological (anemia).

Sampling

Ultrasound guided FNA of the ileocecocolic mass revealed severe inflammation. Postmortem samples of the mass (taken several weeks later) revealed malignant B cell neoplasm deriving from an abdominal lymph node with multifocal amyloid deposition. The bulk of the mass was composed of amyloid deposition with interspersed clusters of plasma cell neoplasia; extramedullary myeloma and secondary systemic amyloid deposition was suspected. The adjacent thickened ileum revealed lymphoplasmacytic enteritis without criteria for neoplasia. Amyloid deposition was present within the infiltrated intestinal wall.