The Use of Sentinel Lymph Node Mapping for Canine Mast Cell Tumors

SIMPLE SUMMARY: Canine mast cell tumors are cutaneous and subcutaneous tumors that spread through the lymphatic system and lead to high mortality rates.

Lymph node mapping, crucial for pinpointing the sentinel lymph node—the initial recipient of lymph from a tumor—is pivotal in diagnosing cancers that spread through the lymphatic system.

Lymph node mapping is critical for assessing disease progression, guiding treatment, and predicting outcomes.

Furthermore, the early detection of lymph node metastases is essential for improving prognosis.

Lymph node mapping is a routinely applied diagnostic technique in humans but a relatively new technique in veterinary oncology; only recently have the first studies been conducted on its application in mast cell tumors.

The primary aim of this article is to summarize the current knowledge on various lymph node mapping methods in canine mast cell tumors, highlighting their advantages, disadvantages, and the importance of this approach both for veterinary practitioners and dog owners.

The sentinel lymph node exploits unique drainage patterns in mast cell tumors, highlighting the role of lymph node mapping in the precise diagnosis and treatment of canine mast cell tumors; the successful diagnosis of mast cell tumors could lead to significant progress in veterinary oncology.

ABSTRACT: Cancer is the leading cause of death in companion animals.

The evaluation of locoregional lymph nodes, known as lymph node mapping, is a critical process in assessing the stage of various solid tumors, such as mast cell tumors (MCTs), anal gland anal sac adenocarcinoma, melanoma, and mammary gland adenocarcinoma.

MCTs are among the most prevalent skin malignancies in dogs.

Staging is used to describe the extent of neoplastic disease, provide a framework for rational treatment planning, and evaluate treatment results.

The aim of this review is to present the current knowledge on sentinel lymph node (SLN) mapping in canine MCTs, its influence on treatment decisions and prognosis, as well as the advantages and limitations of different SLN techniques currently available in veterinary oncology.

A search methodology was adopted using the PubMed, Scopus, and Google Scholar databases.

Critical analyses of up-to-date research have shown that lymphoscintigraphy can achieve a lymph node detection rate of between 91 and 100%.

This method is becoming increasingly recognized as the gold standard in both human and veterinary medicine.

In addition, initial studies on a limited number of animals have shown that computed tomographic lymphography (CTL) is highly effective in the SLN mapping of MCTs, with detection rates between 90 and 100%.

The first study on contrast-enhanced ultrasound (CEUS) also revealed that this advanced technique has up to a 95% detection rate in canine MCTs.

These methods provide non-ionizing alternatives with high detection capabilities.

Furthermore, combining computed tomography and near-infrared fluorescence (NIR/NIR-LND) lymphography is promising as each technique identifies different SLNs.

Indirect lymphography with Lipiodol or Iohexol is technically feasible and may be also used to effectively detect SLNs.

The integration of these mapping techniques into routine MCT staging is essential for enhancing the precision of MCT staging and potentially improving therapeutic outcomes.

However, further clinical trials involving a larger number of animals are necessary to refine these procedures and fully evaluate the clinical benefits of each technique.