Histiocytic Sarcoma In a 4-Year-Old Female Spayed Ferret: Our Case of the Month 2021

June 18, 2021
The Focal Zone

Dr. Cathy Jarrett, owner of Potomac Mobile Veterinary Ultrasound, performed the ultrasound and FNA procedures on Olive, a very sick little ferret. Histiocytic sarcoma is described in the literature as a rare, very aggressive hematopoietic tumor of histiocytes, in ferrets most commonly found in the spleen but can be elsewhere. Performing the FNA procedure in two sites as Dr Jarrett did here increased the probability of obtaining the information needed for Dr. Mary Ann McKissick and the team at Buckeystown Veterinary Hospital, allowing them to expeditiously create a care plan with Olive’s family. Interpretation of images by: Eric C Lindquist BS, DMV (Italy), DABVP.


Weight loss, diarrhea, decreased appetite, occasional weakness. Glucose checks have been consistently in the low 60s. HCT over 60%, ALT 299, AST 141, BG 61. Recheck BG 64.

Image Interpretation

Spleen: The spleen revealed an expansive target type nodule that measured 1.8 cm at the cranial pole. The spleen was otherwise enlarged with scalloping contour with free fluid.

Pancreas: The left limb of the pancreas revealed heterogenous parenchymal changes with a hypoechoic nodule or overlying lymph node measuring 0.74 cm.

Gastrointestinal: The gastrointestinal tract revealed diffuse, hyperechoic fogging or overlay throughout the small intestine as well as areas of mucosal striations and speckling. This striation + fogging effect appeared to exclusively affect the mucosal layer with the submucosa, muscularis and serosa left in-act. Reactive mesentery was present associated with the serosa indicative of active inflammation. This is most consistent with protein losing enteropathy/lymphangectasia. Full thickness biopsies or endoscopic guided biopsies would be ideal to confirm. A cluster of mesenteric lymph nodes with distorted architecture was noted. The largest of which measured 2.04 x 1.02 cm.

Free Abdomen: Minor areas of free fluid was present.


Following the ultrasound report, FNAs of the spleen and pancreatic nodule were performed. Cytology of both sites indicated high suspicion for histiocytic sarcoma in the spleen (95% confidence) and the pancreatic lesion (80% confidence). Biopsy recommended for confirmation.


Infiltrative splenic pattern with multi-focal lymphadenopathy. Mucosal fogging. Left pancreatic nodule.


Ultrasound-guided FNA of the spleen and lymph nodes is recommended. The 0.74 cm hypoechoic nodule on the left limb of the pancreas may represent insulinoma versus distorted lymph node as they cannot be differentiated one from the other. FNA would be appropriate upon the left pancreatic nodule to distinguish insulinoma from the lymph node as well as FNA of the spleen and accessible mesenteric lymph nodes. The free fluid is likely owing to lymphatic obstruction in this patient. There is concern for lymphoma +/- insulinoma. So far the patient is doing well clinically except for loose stool. The patient was started on prednisolone and oncology consult is being considered as an option. Followup: Olive did well on prednisolone 1 mg q 12 hours and metronidazole 10 mg q 12 hours, was eating and playing. She started to become very weak with decreased appetite daily the first week of June. Her owners elected humane euthanasia for her on June 4, while she still had her naturally good spirit. Olive lived happily until about 5 weeks after her initial diagnosis.

Spleen with expansive target nodule at the cranial pole.
Enlarged, hypoechoic rounded multi-focal lymphadenopathy
Suspect pancreatic or lymph node mass, undifferentiated – lack of architecture.
Pancreatic nodule or overlying lymphadenopathy.