The accuracy of fine-needle aspiration cytology in the diagnosis of canine skin and subcutaneous masses

Abstract

A retrospective evaluation of cytologic and histopathologic specimens from 300 cutaneous and subcutaneous palpable lesions in dogs was performed. Preoperatively, specimens were obtained from each formation by fine-needle aspiration biopsy (FNAB). Samples for histopathology were obtained by surgical excision biopsy or at necropsy. The concordance and the accuracy of FNAB for the diagnosis of neoplasia were determined using histopathology as a gold standard. Fifty-two cases were considered as unsatisfactory and were excluded from the study (retrieval rate 82.66%, n = 248). Neoplasia was diagnosed in 193 cytologic specimens. In 190 cases, neoplasia was confirmed by histology (98.44% true positive). Fifty-five cytologic specimens were classified as non-neoplastic. In 35 (63.63%) cases, the cytologic diagnoses were in agreement with the histologic diagnosis (true negative), while in 20 (36.37%) cases, a false negative diagnosis of neoplasia was made by cytologic examination. Based on the results from our study, there was 88.7% (220/248) agreement between cytologic and histologic diagnoses. In diagnosing neoplasia cytology had a sensitivity of 90.47%, a specificity of 97.22%, a positive predictive value of 98.44%, and a negative predictive value of 63.63%.