RESUMEN
In humans, soft tissue spindle cell sarcomas (STSCS) grading is considered a useful parameter in determining prognosis and therapy, and it is recognized as an important prognostic factor in canine STSCS. The purpose of this study was to assess the utility and the accuracy of a cytologic grading system on fine needle aspiration cytology (FNAC) smears of canine and feline cutaneous and subcutaneous STSCS .Thirty-three cases of cytologically diagnosed STSCS were included. The smears and their tumour sections were cytologically and histologically graded, according to established methods in human oncology.Canine STSCS showed a cyto/histologic concordance in 12/20 cases (60%). Concordance was observed in 4/8 (50%) of grade 1, in 8/12 (67%) of grade 2, and in 0 cases of grade 3. Feline STSCS showed concordance in 11/13 cases (85%). Concordance was observed in 5/6 (83%) of grade 1, in 4/4 (100%) of grade 2, and in 2/3 (66.6%) of grade 3 cases. The overall concordance in the entire canine and feline population was 70%. The gradewise concordance was 65% in grade 1, 75% in grade 2, and 66% in grade 3 cases. The overall concordance is similar to that reported in humans. Although a wider population is required to strengthen our findings, these results suggest that cytologic grading of STSCSs may be a useful tool for therapeutic and prognostic evaluations in dogs and cats.