Sentinel Lymph Node Mapping with Indirect Lymphangiography for Canine Mast Cell Tumour

Mast cell tumour (MCT) is a common cutaneous and subcutaneous neoplasia in dogs. It canmetastasise to lymph nodes (LNs), and this adversely affects the prognosis and treatment. The studyaims to evaluate the SLN mapping of MCTs with radiographic indirect lymphography. Dogs thatunderwent clinical staging were prospectively enrolled. Lipiodol was injected around the MCT orthe surgical scar. After 24 h, LNs that picked up contrast were radiographically assessed. Twenty-sixdogs with 29 MCTs were included. MCTs were confirmed histologically, while SLNs were evaluatedeither by cytology and/or histology. SLNs were detectable in 23 dogs with 26 MCTs. Lymphaticvessels were visible in 19 MCTs. In nine MCTs, at least two SLNs picked up contrast. In particular,seven MCTs involved two SLNs, and two MCTs involved three different SLNs. In nine MCTs, atleast a SLN was metastatic. This study indicates that the lymph drainage pattern of the MCTs maybe different for each MCT, and more than one SLN can be involved. Indirect lymphangiographywith Lipiodol allowed the detection of the SLN in 90% of MCTs. This provided clinically relevantinformation to remove the LN and stage the patient.