February 2022 Case of the Month.

Patient Information:

Age: 12 years

Gender: Castrated Male

Breed: Shepherd Mix

Weight: 57 pounds

History:

Presented for abdominal ultrasound to evaluate for underlying cause of intermittent decreased appetite and a possible abdominal mass. Popliteal lymph nodes were also noted to be mildly enlarged on physical examination.

Abdominal ultrasound findings:

Liver:Normal size with rounded shape and hypoechoic echogenicity. No focal lesions are appreciated.

Spleen: Diffusely enlarged measuring 2.8cm having scalloped shape and a miliary pattern of hypoechoic micronodules throughout.

Stomach: The stomach is empty and collapsed with diffusely thickened walls (11.0mm)

Lymph Nodes: Multiple mesenteric lymph nodes are moderately enlarged (~1.4cm depth) with rounded shape having homogenous hypoechoic echogenicity.

The medial iliac lymph nodes and inguinal lymph nodes are severely enlarged (medial iliacs Lt/Rt 1.2/2.3cm; right inguinal 0.9cm) with rounded shape having homogenous hypoechoic echogenicity.

Other lymph node populations throughout the abdomen are also enlarged, rounded, with homogenous hypoechoic echogenicity.

Mesentery: diffusely hyperechoic throughout the abdomen

Differentials:

Liver - the findings are moderate - DDx:

a) Common: Hepatitis (acute or active): Vacuolar hepatopathy, Passive congestion (e.g., dilated hepatic veins and CVC), Cholangiohepatitis/cholangitis (acute or active), Neoplasia (e.g., lymphoma, sarcoma, histiocytic neoplasia, or mast cell disease)

b) Less Common: Immune-mediated hemolytic anemia, Leptospirosis, Histoplasmosis, Amyloidosis, Leukemia

Stomach wall thickening - the findings are moderate - DDx: adenocarcinoma vs. infiltrative neoplasia (lymphosarcoma) vs. leiomyosarcoma vs. leiomyoma vs. benign mucinous hypertrophy or gastric ulcer.

Spleen - the findings are moderate - DDx: extramedullary hematopoiesis (EMH) vs. infiltrative neoplasia vs. benign nodular regeneration

Lymph nodes - the findings are severe - DDx: infiltrative neoplasia (lymphoma vs. mast cell vs. other) vs. IBD vs. infection vs. reaction vs. metastatic neoplasia

Mesentery - the findings are moderate - DDx: peritonitis - inflammation vs. paraneoplastic reaction vs. infectious vs. fibrosis vs. other.

Additional Diagnostics:

Ultrasound guided fine needle aspirates of the right medial iliac lymph node and the spleen were obtained and submitted to Eastern Vet Path for analysis

Cytology:

Microscopic Description

The slides from the two locations appear very similar, are highly cellular, and consist of few to numerous red blood cells and a nucleated cell population predominated by large immature lymphocytes, with few small lymphocytes, and occasional neutrophils. The slides from the spleen also consist of few aggregates of splenic stroma and few hematopoietic precursors. The large lymphocytes consist of a small amount of basophilic cytoplasm, a perinuclear clear area, and a large round nucleus with a finely-stippled chromatin pattern. Occasional mitotic figures are noted. The background consists of many lymphoglandular bodies and occasional free nuclei.

Diagnosis:

Spleen: High-grade lymphoma definitive (100% confidence)

Right medial iliac lymph node: High-grade lymphoma definitive (100% confidence)

Treatment Options:

Referral for oncology consultation was recommended for optimal treatment plan. Alternatively, for immunophenotyping (T vs B cell), ICC staining of slides could be performed and/or a lymphoma chemotherapy protocol could be initiated. Palliative treatment options could also be considered based on the patient's clinical condition.