Cytological and histopathological diagnosis of canine skin tumours

Nine canine skin tumours were studied by cytology and confirmed by histopathology. Fine needle aspiration biopsy (FNAB) technique was found to be superior to impression and teased smear techniques as it yielded high cellularity in epithelial tumours. However, impression smears were best suited for mesenchymal tumours. Ethanol and ether: ethanol (1:1) fixatives were better than air drying and methanol fixations. Cytoplasm stained well with May-Grunwald Giemsa in osteosarcoma and haemangiopericytoma. Nucleoli stained well with Wright's stain in osteosarcoma. Diff-Quik was suitable for immediate diagnosis. Characteristic cytological features like plasmacytoid appearance with perinuclear space of Golgi zone (osteosarcoma), swirling pattern of tadpole shaped cells (haemangiopericytoma,) and signet ring cells (mixed mammary gland tumour) were seen. Cytological diagnosis yielded definite results in epithelial tumours than in mesenchymal tumours barring osteosarcoma.