Preoperative planar lymphoscintigraphy allows for sentinel lymph node detection in 51 dogs improving staging accuracy: Feasibility and pitfalls

Abstract

Sentinel lymph node (SLN) mapping is the current gold standard for the oncological staging of solid malignancies in humans. This prospective observational study describes the feasibility and the limits of preoperative lymphoscintigraphy for SLN detection in dogs with spontaneous malignancies and the improvements in staging accuracy. Client-owned dogs with confirmed malignant neoplasia and absence of distant metastasis were prospectively enrolled. Lymphoscintigraphy was performed after the peritumoral injection of Technetium-99m labeled nanocolloids. Regional dynamic and static images were acquired, with and without masking of the injection site with a lead shield. The dogs were then subjected to surgery for tumor excision and SLN extirpation. Intraoperative SLN detection was performed by combining methylene blue dye and a dedicated gamma probe. Overall, 51 dogs with a total of 60 solid malignant tumors were enrolled. Lymphoscintigraphy identified at least one SLN in 57 of 60 cases (95%). The SLN did not always correspond to the regional lymph node (35/57, 61.4%).The use of a lead shield, masking the injection site, markedly improved the SLN visibility. The median time of SLN appearance was 11.4 ± 9.3 min. No side effects were observed. Preoperative lymphoscintigraphy allows for SLN detection in dogs and can improve staging accuracy by either identifying the SLN in a different lymphosome than clinically expected or discriminating the draining node in uncertain cases. The combined use of preoperative and intraoperative techniques is recommended to increase the SLN detection rate.

Histologic grade has a higher‐weighted value than nodal status as predictor of outcome in dogs with cutaneous mast cell tumours and overtly metastatic sentinel lymph nodes

“…Sentinel LNs were identified by means of lympho-CT or scintigraphy and/or nodal methylene blue dye uptake after peritumoral injection. 11,12 All "hot" and/or "blue" LNs were removed and submitted for histopathology; only dogs with at least one HN3 LN were ultimately included.…”

Assessing the Risk of Nodal Metastases in Canine Integumentary Mast Cell Tumors: Is Sentinel Lymph Node Biopsy Always Necessary?

“…The SLN was identified by pre-operative lymphoscintigraphy and excised under intraoperative gamma-probe guidance as previously described [6,7,12]. Briefly, planar lymphoscintigraphy was performed the day before or the same day of surgery and consisted of a peritumoral injection of Technetium-99m-human serum albumin colloid and identification of one or more draining lymphocenters that included the SLN/SLNs using a gamma camera.…”

Sentinel Lymph Node Biopsy Is Feasible in Dogs with Scars from Prior Local Excision of Solid Malignancies

“…The sentinel lymph node (SLN), defined as the first lymph node on the drainage pathway of a tumor, may differ from the anatomically closest regional lymph node (RLN) in 22–63% of tumor-bearing dogs [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 ], and metastases to the SLN have been reported in up to 50–70% of dogs, depending on the tumor type [ 2 , 4 , 5 , 6 , 9 , 10 , 11 , 12 ]. Given the well-accepted impact of the accurate detection of nodal metastases on staging and treatment recommendations, the implementation of sentinel lymph node biopsy (SLNB) in the surgical management of canine malignancies has gained increased interest in recent years [ 8 , 13 , 14 ].…”

“…Given the well-accepted impact of the accurate detection of nodal metastases on staging and treatment recommendations, the implementation of sentinel lymph node biopsy (SLNB) in the surgical management of canine malignancies has gained increased interest in recent years [ 8 , 13 , 14 ]. Various mapping techniques have been described to detect SLN in dogs, including lymphoscintigraphy and methylene blue, near-infrared fluorescence (NIRF) imaging, indirect lymphography with lipidic or aqueous contrast mediums, and contrast-enhanced ultrasonography (CEUS) [ 2 , 4 , 5 , 7 , 8 , 9 , 15 , 16 , 17 , 18 ]. Regardless of the technique used, the combination of a preoperative and intraoperative mapping method is recommended to increase the ability to correctly detect and excise the SLN [ 6 , 16 ].…”

“…Regardless of the technique used, the combination of a preoperative and intraoperative mapping method is recommended to increase the ability to correctly detect and excise the SLN [ 6 , 16 ]. However, the required technologies and human resources are currently not widely available in veterinary practices and only a few referral centers have access to SLN mapping techniques [ 6 , 7 , 16 ]. Consequently, dogs are increasingly presented to specialized centers for secondary lymph node staging after the primary tumor has been excised at the first-line care institution.…”