Case Study

Lymphoma diagnosed by Tru-cut biopsy of mesenteric lymph nodes in a pruritic 2 year old Labrador Retriever

A 2-year-old FS Labrador Retriever was presented for the evaluation of pruritus and being more affectionate (clingy) than usual. The dog had a previous history of a histiocytoma and Lyme disease which had been treated. Generalized areas consisting of collarettes and seborrhea were present on her dorsum. Samples obtained for a fungal assay were negative. A course of antibiotics was prescribed. The dog’s skin condition continued to worsen and she developed circular alopecic areas on her ventrum, however, the skin on her dorsum had improved. Skin scrapings were negative. A skin biopsy was advised if her condition did not resolve. The patient was presented again with signs of lethargy, anorexia, gagging, and vomiting. She had not eaten a full meal in 6 days. On physical exam, her temperature was within normal limits and no abnormalities were noted on evaluation of her heart and lungs and abdomen. Blood chemistry revealed hypoalbuminemia, a high CK, and hyperamylasemia. CBC found mild anisocytosis, leukocytosis, neutrophilia, monocytosis and lymphopenia. A Lyme Quantative C6В® result was elevated and antibiotics were prescribed.

DX

Lymphoma

Sonographic Differential Diagnosis

Mesenteric lymphadenopathy. Small intestinal infiltrative change.

Image Interpretation

There was evidence of small intestinal change with severely enlarged and hypoechoic distorted lymph nodes. The mesentery was reactive throughout the abdomen.

Outcome

A board certified oncologist was contacted and the Madison Wisconsin chemotherapy protocol was chosen. The dog tolerated the first treatment fairly well, but she became neutropenic (segmented neutrophils 1,508) prior to the second treatment and treatment had to be delayed. A CBC was repeated a few days later and showed a leukocytosis, elevated segmented neutrophils (43,860), which showed signs of toxicity and Dohle bodies, as well as an elevated number of bands. A lymphocytosis, eosinopenia, and monocytosis were also present. She received her treatment of chemotherapy and antibiotics were prescribed. On re-evaluation, the dog was lethargic and had labored breathing. Physical exam revealed tachycardia (the dog was nervous), pink mucous membranes, CRT<2 seconds, and enlarged submandibular and prescapular lymph nodes. All other lymph nodes were considered to be normal.) No abnormalities were noted on abdominal palpation. The CBC showed a decreased RBC count, low HCT with mild polychromasia, as well as a leukocytosis, neutrophilia, lymphopenia, and eosinopenia. Despite 5 treatments of chemotherapy the dog did not respond clinically and chemotherapy was discontinued. The dog's quality of life continued to decline during the next few days and humane euthanasia was performed.

Comments

When approaching the mesenteric root LN masses that encompass the mesenteric artery (Video 2) the sonographer can angle the needle trajectory away from the vasculature to avoid a dangerous hemorrhage (Video 3). Core biopsy at times is necessary in these cases of infiltrated and inflamed lymph nodes to discern the two pathological states.

Clinical Differential Diagnosis

Deep pyoderma with a secondary bacterial infection and inflammation, lymphoma-paraneoplastic dermatitis, erythema multiforme/other immune mediated dermatopathy, occult dermal parasites.

Sampling

The PTT/PT were both within the normal reference range. US-guided FNA and US-guided Tru-cutВ® biopsy were both performed. Cytology results of the lymph node aspirate showed severe lymphoid hyperplasia. The intestinal lymph node biopsy was highly suspicious of lymphoma (video 3).