Correlation between cytologic and histopathologic diagnoses of bone lesions in dogs: a study of the diagnostic accuracy of bone cytology.

BACKGROUND

The diagnostic value of cytology compared with histopathology varies by tissue, but there is little information regarding this comparison involving canine bone.

OBJECTIVES

The objective of this retrospective study was to compare primary pathologic processes for cytology and histopathology of canine bone lesions. We adopted a proposed standardized format for reporting studies of diagnostic accuracy.

METHODS

A computer search of canine medical records at the University of Minnesota Veterinary Medical Center from September 2002 through October 2006 identified 52 bone cytology samples that had incisional (IncB) and/or excisional (ExcB) biopsy performed. The primary pathologic process was determined by evaluation of original reports. Cytologic vs IncB and cytologic vs ExcB were compared pairwise for agreement. Agreement was compared for neoplastic and non-neoplastic processes using the combined IncB/ExcB data, which included all ExcB (n=21) and IncB when that was the only biopsy available (n=31). Combined data were used to determine the effect of cytology cellularity on the diagnostic correlation.

RESULTS

The correlation in primary process between cytology and IncB was 71%, and for ExcB was 71%. For lesions with a cytologic diagnosis of neoplasia compared with the combined IncB/ExcB data set, cytology and histopathology agreed in 92% of cases, which was significantly greater (P<.0001, chi2) than the 27% for non-neoplastic processes. Cytology cellularity significantly affected rates of correlation (P=.026), with high, moderate, and poor cellularity samples having concordant primary processes in 88%, 77%, and 47% of cases, respectively.

CONCLUSIONS

Cytologic diagnosis of neoplasia for samples collected from canine bone correlates better with histopathology than cytologic diagnosis of non-neoplastic proliferative processes or inflammation. Cytologic diagnoses from highly cellular samples are more likely to correlate with histopathology than those from less cellular samples.