Overview
Definition:
Axillary Reverse Mapping (ARM) is a technique used during axillary lymph node dissection (ALND) or sentinel lymph node biopsy (SLNB) in breast cancer surgery to identify and preserve lymphatic channels draining into the axilla from the ipsilateral arm and hand
This involves injecting a tracer (dye, radiotracer, or fluorescent agent) into the arm, allowing surgeons to differentiate between lymphatics draining the breast/axilla and those draining the limb, thereby minimizing disruption of the latter and potentially reducing the risk of postoperative lymphedema.
Epidemiology:
Lymphedema is a significant complication after breast cancer surgery, affecting an estimated 15-30% of patients undergoing ALND and a smaller percentage after SLNB
Risk factors include extent of nodal dissection, radiation therapy, chemotherapy, obesity, and infection
The incidence of clinically significant lymphedema can be reduced with advanced surgical techniques.
Clinical Significance:
Post-mastectomy lymphedema can cause chronic morbidity, impacting quality of life due to pain, heaviness, restricted mobility, and recurrent infections (cellulitis)
ARM aims to preserve the lymphatic drainage of the arm, acting as a critical preventive strategy to maintain normal limb fluid balance and function
Its understanding and application are vital for surgeons managing breast cancer patients.
Indications
Indications For Arm:
ARM is primarily considered in patients undergoing ALND for breast cancer, particularly those with a high risk of lymphedema
It may also be considered in select SLNB cases where extensive axillary dissection is anticipated or in complex oncoplastic reconstructions
Patients with pre-existing venous insufficiency or conditions affecting lymphatic drainage may also benefit.
Contraindications:
Absolute contraindications are rare but may include active infection at the injection site or severe coagulopathy
Relative contraindications might be a patient's refusal of the procedure or lack of surgeon expertise in performing ARM.
Patient Selection:
Careful patient selection is key
Factors influencing selection include tumor stage, nodal status, planned extent of axillary surgery (e.g., need for ALND versus SLNB alone), and patient's overall health status and risk factors for lymphedema.
Preoperative Preparation
Patient Counseling:
Thorough discussion with the patient about the procedure, its potential benefits in reducing lymphedema, and the associated risks and limitations is crucial
Informed consent must be obtained.
Tracer Selection:
Various tracers can be used, including vital blue dyes (e.g., Patent Blue V, isosulfan blue), technetium-99m radiotracers (for SLNB), or indocyanine green (ICG) for fluorescence imaging
The choice depends on surgeon preference, available resources, and the primary surgical procedure.
Injection Technique:
The tracer is typically injected subcutaneously into the dorsal aspect of the ipsilateral hand or forearm, often multiple sites, distal to the planned axillary dissection area
This encourages retrograde flow through the lymphatic channels draining the limb.
Procedure Steps
Tracer Injection:
Following anesthesia and sterile preparation, the chosen tracer is injected into the limb's lymphatic system
For blue dyes, injection is usually done 10-15 minutes before incision to allow for lymphatic uptake and migration.
Lymphatic Identification:
During surgery, the surgeon meticulously identifies the blue-stained lymphatic vessels draining from the arm/forearm towards the axilla
These are differentiated from the lymphatics draining the breast and axillary contents, which are typically removed or biopsied.
Preservation Of Arm Lymphatics:
The identified ARM lymphatic channels are carefully dissected free and preserved
These vessels are then rerouted or directed to drain away from the axillary space, ensuring continued drainage of the limb.
Standard Axillary Dissection:
Concurrent standard sentinel lymph node biopsy or axillary lymph node dissection is performed, taking care not to injure the preserved ARM lymphatics.
Postoperative Care
Wound Care:
Standard surgical wound care is provided
Dressings should be monitored for excessive drainage
Patients are advised to report any signs of infection.
Limb Management:
Patients are encouraged to use the affected arm as tolerated
Gentle range-of-motion exercises can be initiated early
Compression garments may be prescribed based on individual risk and surgeon preference.
Monitoring For Lymphedema:
Regular follow-up appointments are scheduled to monitor for any signs or symptoms of lymphedema, including arm circumference measurements, patient-reported heaviness, swelling, or discomfort
Early detection and management are key.
Patient Education:
Patients receive education on lymphedema risk reduction strategies, including avoiding constrictive clothing, extreme temperatures, and vigorous activities on the affected arm, and maintaining good skin hygiene.
Complications
Early Complications:
Potential early complications include bruising or hematoma at the injection site, transient skin discoloration along lymphatic pathways, minor wound infections, or seroma formation in the axilla
Injury to the preserved ARM lymphatics during surgery can occur if not identified and handled with care.
Late Complications:
The primary late complication ARM aims to prevent is chronic lymphedema of the upper extremity
If ARM is unsuccessful or not performed, persistent or progressive swelling, fibrosis, and recurrent cellulitis can occur
In rare cases, the preserved ARM lymphatics themselves could become occluded or damaged, leading to arm swelling.
Prevention Strategies:
Meticulous surgical technique, careful identification and preservation of ARM lymphatics, and appropriate postoperative management are the cornerstones of preventing complications
Avoiding aggressive dissection of the identified ARM channels and ensuring adequate rerouting are critical steps.
Key Points
Exam Focus:
ARM is crucial for reducing lymphedema after ALND
It involves injecting tracers into the arm to identify and preserve limb lymphatic drainage
Key tracers include blue dyes and radiotracers
Successful ARM minimizes disruption of arm lymphatics, maintaining limb fluid balance
Understand the indications, technique, and postoperative care.
Clinical Pearls:
Inject tracer distally in the arm
Identify blue-tinged vessels draining towards the axilla FROM the arm
Carefully dissect and preserve these vessels, ensuring they are directed away from the axillary space
Intraoperative near-infrared fluorescence imaging with ICG can enhance visualization of lymphatics
Consider ARM in all patients undergoing ALND.
Common Mistakes:
Failure to inject tracer sufficiently distal or with adequate timing
Mistaking breast/axillary lymphatics for arm lymphatics
Inadvertent injury to preserved ARM lymphatics during dissection or closure
Not adequately rerouting the preserved lymphatics
Inadequate postoperative limb care and patient education.