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

Abstract

Sentinel lymph node (SLN) biopsy is a well-established staging tool in canine oncology. This study aims to explore the feasibility of SLN biopsy in dogs with scars from prior excised solid malignancies that were referred for further tumor staging and/or adjuvant treatment options. Mapping was either performed using radiopharmaceutical, methylene blue, and/or near-infrared fluorescent (NIRF) imaging. Thirty-three dogs with 34 scars from prior excision of the mast cell tumor (MCT) (n = 29), soft tissue sarcoma (n = 2), oral melanoma (n = 1), subungual melanoma (n = 1), and mammary adenocarcinoma (n = 1) were retrospectively enrolled. Primary treatment consisted of curative intent/wide tumor excisions in 50.0% of dogs and marginal excision in the remaining 50.0%. The median time between tumor excision and SLN biopsy was 50 days (range 17–110 days). The procedure was successful in 31/34 scars, translating to a detection rate of 91.2%. The SLN did not correspond to the regional lymph node in 19/31 scars (61.3%). SLN metastases were histologically identified in 13/31 (41.9%) dogs, all of them affected by MCT. Based on our results, SLN biopsy using lymphoscintigraphy/methylene blue and/or NIRF is feasible in dogs presenting with scars from the prior surgical excision of solid tumors, and should be suggested for accurate nodal staging.

The Role of Sentinel Node Mapping and Lymphadenectomies in Veterinary Surgical Oncology

“…contrast-enhanced ultrasound (CEUS) [32], single-photon emission computed tomography (SPECT) [33], positron emission tomography (PET) [34], pre-and intraoperative lymphoscintigraphy, and the injection of blue dyes for direct visualization or fluorescent dyes for near-infrared (NIR) fluorescent imaging [35]. Corresponding evaluations of indirect radiographic [36][37][38] and CT lymphography [39][40][41][42], lymphoscintigraphy [15,20,24,[43][44][45][46][47], CEUS [25,48], methylene blue staining [20,24,47], and NIR-lymphography [14,47,[49][50][51] are also available for dogs and, most recently, also for cats [26,52].…”

“…Lately, several metareviews in human medicine have confirmed NIR imaging using ICG as a reliable mapping technique compared with the gold standard lymphoscintigraphy [35,77]. After NIR SLN mapping in dogs was initially described in experimental studies in dogs and pigs [50], it is now gaining increased interest in veterinary surgical oncology [14,49,52]. Beer et al published a retrospective study on NIR lymphography in dogs with mast cell tumors.…”

“…A first case report showing the feasibility of SLN mapping in a cat also bearing a mast cell tumor has just been published, followed by a pilot study in cats with different solid neoplasms [26,52]. Finally, Gariboldi et al very recently published a study that proved that the SLN mapping of scars from previous tumor excision is also possible using lymphoscintigraphy or NIR lymphography [49].…”

“…The improved visualization of small and nonpalpable nodes results in a significantly increased success rate of lymphadenectomies compared with unguided lymphadenectomies in dogs [14]. No mapping-related complications have been reported in dogs or cats [14,49,52,78,79]. The disadvantages of NIR include its low depth of penetration, limited to a few millimeters to centimeters, and that it does not allow the identification of sentinel nodes in body cavities without surgical access to allow visual inspection [72].…”

Sentinel Lymph Node Mapping and Biopsy in Cats with Solid Malignancies: An Explorative Study

“…The advantages of the incorporation of SLN mapping and biopsy have been largely reported in human medicine and include accurate tumor staging and reduced morbidity compared to radical nodal dissection [ 1 , 7 ]. Similarly, in tumor-bearing dogs, a benefit in terms of accuracy in staging has been documented, and morbidity of the procedure is reportedly low, although studies that compare the morbidity of RLN vs. SLN extirpation are currently not available in the veterinary literature [ 1 , 7 , 22 , 23 , 24 ]. Disadvantages of SLN extirpation include the need for dedicated technologies and the learning curve for the mapping procedure, although the incorporation of SLN biopsy seems to be justified by the well-documented impact of correct nodal staging on prognosis and treatment recommendations for various tumor types [ 3 , 25 , 26 , 27 ].…”