Case Study

Mast Cell Neoplasia in a 15 year old MN DSH cat

This 15-year-old MN controlled hyperthyroid DSH was presented for hyporexia, diarrhea, and hiding. The physical exam revealed poor body condition and palpably ropey intestines. The CBC was normal while the blood chemistry analysis revealed subnormal thyroid levels and mild azotemia. The urinalysis was normal other than mild evidence of UTI.

This 15-year-old MN controlled hyperthyroid DSH was presented for hyporexia, diarrhea, and hiding. The physical exam revealed poor body condition and palpably ropey intestines. The CBC was normal while the blood chemistry analysis revealed subnormal thyroid levels and mild azotemia. The urinalysis was normal other than mild evidence of UTI.

DX

Mast cell neoplasia

Sonographic Differential Diagnosis

Given the degree of lymph node enlargement, primary consideration is given to neoplasia and lymphosarcoma is primarily suspected. Malignant transformation of chronic inflammatory bowel disease may have occurred. Infiltration with mast cell tumor would be considered less likely.

Image Interpretation

The three segments of bowel included in this image are moderately to markedly thick walled. The intestinal muscularis layer is most severely thickened, occupying approximately 20 to 40% of total wall thickness. Discernible intestinal wall layering is maintained. A markedly enlarged, mildly hypoechoic lymph node is present in the center of the image. The lymph node is coarse and lacks delineation between the echogenic medulla and hypoechoic cortex.

Outcome

Diphenhydramine injection was administered prior to the sampling procedure on suspicion of possible mast cell infiltration. The smaller gauge needle was selected for similar reasons and to avoid hemodilution of the sample. The patient responded mildly well to a prednisolone/Leukeran protocol over the next 3 months but was then euthanized due to further clinical deterioration.