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33rd Annual Scientific Meeting proceedings


Stream: SA   |   Session: Lymph Nodes
Date/Time: 06-07-2024 (09:00 - 09:45)   |   Location: Auditorium 4
Minimally invasive approach to lymph node identification and removal/ablation
Buote NJ*
Cornell University College of Veterinary Medicine, Ithaca, USA.

Laparoscopic lymph node removal in dogs, also known as laparoscopic lymphadenectomy, is a minimally invasive surgical procedure used to remove enlarged or abnormal lymph nodes from the abdominal or thoracic cavity. This procedure offers several advantages over traditional open surgery, including smaller incisions, reduced post-operative pain, faster recovery times, and decreased risk of complications.

Laparoscopic and thoracoscopic lymph node removal in dogs is usually paired with surgical treatments for various conditions, including cancer, infection, and inflammatory diseases affecting the lymphatic system. The most common indication for lymphadenectomy is cancer with lymph node extirpation for anal sac carcinoma metastasis and lung tumor metastasis at the top of the list. Imaging of the lymph nodes usually occurs preoperatively with contrast CT. Intraoperatively imaging of the lymph nodes can be accomplished with near-infrared technology or other dyes (methylene blue).

Abdominal
Sentinel Lymph Node mapping techniques have been reported for AGASACA:

Normal anal sac (not AGASACA) – SLN mapping via lymphoscintigraphy described [Ref: Linden et al VRU 2019]

CTL for dogs with AGASACA [Ref: Majeski/Steffey et al VRU 2017]

Intra-op ICG SLN mapping for dogs with AGASACA – no discussion on patient/port positioning, what LNs able to be identified/accessed [Ref: Thomson Vet Clin SA 2024]

There has been a confirmed large variability in SLN for AGASACA with the potential for divergence in findings between pre-op & intra-op techniques. Pre-op imaging is useful for characterizing all LNs & providing a roadmap to each LN, including suspected SLNs, but intra-op SLN mapping is also beneficial in identifying LNs & should ideally enable visualization of the entire LN basin given the potential for variability in findings.

MIS FOR ILIOSACRAL LNS IN DOGS

-         Intradermal/popliteal LN ICG administration (*not SLN mapping for AGASACA) MIS extirpation of iliosacral LNs in canine cadavers – positioned in dorsal recumbency, Trendelenburg, 3 ports; mainly evaluated MILNs [Ref: Sanchez-Margallo et al PLOS ONE 2020]

-         MIS for unilateral (ipsilateral) MILNs in normal dogs – positioned in lateral recumbency [Ref: Steffey et al Vet Surg 2015]

-         MIS for bilateral MILN extirpation by ventral approach in normal dogs – did not also extirpate IILNs or sacral LNs [Ref: Lim et al J Vet Med Sci 2017]

-         MIS for iliosacral LN extirpation using intra-op ICG SLN mapping for AGASACA – no discussion on patient/port positioning, what LNs able to be identified/accessed [Ref: Thomson Vet Clin SA 2024]

Thoracic
SLN mapping techniques reported for lung in normal dog models only:

Normal dog lung (not pulmonary tumors), animal model – intra-op SLN mapping via technetium & isosulfan blue; no description on approach [Ref: Nwogu et al Cancer Invest 2002]

Normal dog lung (not pulmonary tumors) – intra-op SLN mapping via lymphoscintigraphy & MB; intercostal thoracotomy [so only visualizing ipsilateral LNs], then removed entire pluck [Ref: Tuohy/Worley Research in Vet Sci 2014]

Normal dog lung (not pulmonary tumors), animal model – CT-lymphography for SLN mapping, then removed pluck in 5/10 dogs & identified these LNs. NOTE: SLNs identified on CTL (normal canine lung) = ipsilateral &/or middle tracheobronchial LNs (for both R & L sided injections), pulmonary LN, mediastinal LN; no contralateral LNs enhanced

Pulmonary tumors in dogs – administered IV ICG (*not SLN mapping) to evaluate tumor/LN fluorescence & margins; reported sensitivity 100% & specificity 75% for diagnosis of LN metastasis – extirpated 13 LNs, evaluated for fluorescence in only 7/13 with fluorescence observed in 3/3 metastatic nodes & 1/4 non-metastatic nodes [Ref: Sakurai et al Front Vet Sci 2023]

MIS FOR INTRATHORACIC LNS IN DOGS

-         VATS extirpation of tracheobronchial LNs described in healthy dogs – unilateral approach, ipsilateral TBLNs only (unable to identify contralateral LNs) + able to identify middle TBLN from R approach only [Ref: Steffey et al Vet Surg 2014]

-         Mediastinoscopy for cranial mediastinal & tracheobronchial lymphadenectomy in canine cadavers. Note: Mediastinoscopy reliably accesses 3-5/14 intrathoracic LN stations in people. [Ref: Gibson/Steffey Vet Surg 2024]

Data collection: dissection times, LN extirpation times, study-defined procedure success scoring for visualization & dissection, modified operative adverse events, technique difficulty (NASA-TLX)

Performed pre- + post-procedureal CT

Documented: L/R TB LNs, sternal LNs, cranial mediastinal LNs

L TBLN identified in 7/7, R TBLN identified n 5/7 (same as CT), R sternal identified in 3/7 (vs. 7/7 on CT), L sternal identified in 2/7 (vs. 6/7 on CT), cranial mediastinal identified in 1/7 (vs. 7/7 on CT)

Concerns with current techniques:

Dorsal recumbency – inability to perform in same positioning as thoracoscopic lung lobectomy

No visualization of lung/mass for simultaneous intra-op SLN mapping

No visualization of middle TB LNs or pulmonary LNs + poor visualization of mediastinal LNs

Complications for these procedures includes hemorrhage, damage to nearby structures (vessels, nerves, lungs, ureters, etc), and rupture of the lymph node capsule.

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