Characteristic lipid profiles of canine non-Hodgkin's lymphoma from surgical biopsy tissue sections and fine needle aspirate smears by desorption electrospray ionization – mass spectrometry

Canine non-Hodgkin's lymphoma (NHL) is a heterogeneous group of cancers representing approximately 15% of all canine cancers. Further, canine NHL mimics human disease in regards to histopathology and clinical behavior and could function as a comparative model. Diagnosis is currently performed by histopathological evaluation of surgical biopsy specimens and fine needle aspirate (FNA) cytology, an alternative and less invasive method for diagnosis. Desorption electrospray ionization – mass spectrometry (DESI-MS) imaging was performed on tissue sections of surgical biopsies and FNA smears. Mass spectra acquired from normal lymph nodes and NHL tumors were explored using multivariate statistics (e.g. principal component analysis). Tissue sections yielded a predicted sensitivity of 100% for normal and 93.1% for tumor. Further, preliminary results suggest B-cell and T-cell lymphoma can be discriminated (CV sensitivity of 95.5% and 85.7%, respectively). Normal and B-cell NHL FNA samples analyzed by DESI produced spectra that were similar to spectra obtained from surgical biopsies. FNA samples were evaluated using a PCA-LDA classification system built using tissue section data, exploring if the chemical information obtained from the different sample types is similar and whether DESI-MS performed on FNA samples is of diagnostic value. FNA prediction rate for normal (85.7%) and B-cell NHL (89.3%) indicated that DESI-MS analysis of FNA, not previously explored, could provide rapid preliminary diagnosis. Certainly, MS provides complementary molecular information to be used in conjunction with histopathology/cytology, potentially improving diagnostic confidence. The methodology outlined here is applicable to canine NHL, further supports canine models of human NHL, and translation to humans is envisioned.