Sensitivity and specificity of methods of assessing the regional lymph nodes for evidence of metastasis in dogs and cats with solid tumors

Objective - To determine sensitivity and specificity of physical examinatio n, fine-needle aspiration, and needle core biopsy of the regional lymph nod es for evidence of metastasis in dogs and cats with solid tumors. Design - Case series. Animals - 37 dogs and 7 cats. Procedure - Regional lymph nodes were evaluated by means of physical examin ation (palpation), fine-needle aspiration, and needle core biopsy. Results were compared with results of histologic examination of the entire lymph no de, the current standard. Results - Tumors included 18 sarcomas, 16 carcinomas, 7 mast cell tumors, a nd 3 other tumors. Carcinomas were more likely to have metastasized to the regional lymph node (7/16 animals) than were sarcomas (2/18). Sensitivity a nd specificity of physical examination were 60 and 72%, respectively. Sensi tivity and specificity of cytologic examination of fine-needle aspirates we re 100 and 96%, respectively. Sensitivity and specificity of histologic exa mination of needle core biopsy specimens were 64 and 96%, respectively. Conclusions and Clinical Relevance - Results suggested that fine-needle asp iration may be a sensitive and specific method of evaluating the regional l ymph nodes in dogs and cats with solid tumors, because results correlated w ell with results of histologic examination of the entire lymph node. Physic al examination alone was not a reliable method and should not be used to de cide whether to aspirate or biopsy the regional lymph nodes.