July's Case of the Month
Sonographic Findings of Intestinal Mast Cell Disease in a DSH
Sonographer: Tyler Anderson, DVM
Patient Information:
Age: 15years
Gender: Spayed Female
Species: Feline
History
The patient presented for increased appetite and thirst. There was also one pound of weight loss documented over a 5-month period. General senior blood work was unremarkable having a mildly elevated SDMA. The patient also has a history of chronic immune-mediated skin disease that is managed by a local dermatologist.
Image Interpretation
Abdominal sonographic findings include moderately to severely thickened small bowel (3.4 to 5.2mm) having a prominent muscularis layer (normal wall thickness ~2.2-2.5mm, > 2.8mm abnormal Norsworthy/Estep et. al. JAVMA, Vol 243, No. 10, November 15, 2013). Segments of distal-transverse and proximal-descending colon have asymmetrically thickened walls with complete loss of normal wall layering layering distinction, measuring ~ 0.6 x 1.6cm in thickness (normal < 0.3cm). Multiple mesenteric lymph nodes are moderately enlarged and abnormally shaped having homogenous hypoechoic echogenicity, measuring ~ 0.9 x 2.1cm. The lymph nodes are surrounded by hyperechoic mesenteric fat, consistent with inflammation. A scant amount of abdominal effusion was also observed.
Diagnosis and Sonographic Analysis:
Differentials for thickened small and large bowel with regional lymphadenopathy include inflammatory bowel disease vs. infiltrative neoplasia (small-cell lymphosarcoma vs mast cell) vs. FIP. Fine needle mesenteric lymph node biopsies were obtained for cytologic review to narrow the differential list.
Case Outcome:
Asymmetric thickening of the small or large bowel is often observed with mast cell disease, but not exclusively. Therefore, as a precautionary measure, the patient was sedated and pre-medicated with diphenhydramine. Biopsy results reveal, “ Suspect metastatic mast cell tumor.” Interpretation provided by: Casey Leblanc DVM, PhD, Diplomate, ACVP (Clinical Pathology).
Sonographer: Tyler Anderson, DVM
Sonographic image of an enlarged, hypoechoic, mesenteric lymph node with surrounding hyperechoic/inflamed mesenteric fat giving the node a “halo” appearance.
Colon casting a dirty acoustic shadow from fecal material. Note the asymmetric thickening of the colonic wall (demarcated with calipers). The asymmetric thickening is characteristic of mast cell disease, but not pathopneumonic.
Another segment of proximal colon with asymmetric thickening. Complete loss of normal wall layering distinction is observed on the thickened left colonic wall, compared to the normal “tiger striped” appearance of the right.
Cytology Interpretation Provided by Casey LeBlanc DVM, PhD, Diplomate, ACVP (Clinical Pathology): Slides from the enlarged mesenteric lymph node consist of a small to moderate amount of cellular debris with numerous red blood cells, few to numerous platelet clumps, scattered leukocytes in proportions consistent with peripheral blood with a mildly increased proportion of eosinophils +/- small lymphocytes, a mildly increased number of mast cells, and occasional small sheets of sheared mesothelial cells.
Special Thanks to DuPont Veterinary Clinic for the interesting case and work-up.