It has been hypothesized that the proximity of the anatomic locations of the arm lymphatic drainage system to the breast lymphatic system in the axilla put the arm lymphatics at risk for disruption during a sentinel lymph node biopsy (SLNB) and/or axillary lymph node dissection (ALND). Therefore, mapping the drainage of the arm in addition to the drainage of the breast during the procedure would potentially decrease the incidence of arm lymphatic disruption and subsequent development of lymphedema while providing adequate axillary breast nodes needed for staging.

Patients will receive an injection of 1.0 mCi of technetium-99m sulfur colloid that will be injected into the sub-dermal subareolar aspect of the affected breast.

On the day of surgery, if the radioactive SLN cannot be located using the gamma probe prior to incision, lymphazurin or methylene blue dye will be used in the breast in the subareolar plexus at the discretion of the surgeon for assistance in identifying the sentinel nodes. This contingency, expected to occur < 3% of the time, will be used since locating the SLN for staging is of greater importance than the study. If radioactive isotope is sufficient to identify the sentinel node draining from the breast, then the blue dye will be injected dermally in the upper inner arm along the bicipital groove of the ipsilateral arm in order to locate the draining lymphatics from the arm. No more than 5cc of blue dye will be injected in any of the above mentioned scenarios. The site of all injections (radioactivity and/or blue dye) will be recorded.

Inclusion Criteria:

• 18 - 100 years old
• Not pregnant or breastfeeding
• Diagnosis of breast cancer requiring LN evaluation for ipsilateral or contralateral breast or prophylactic mastectomy
• Willing participation after obtaining informed consent

Exclusion Criteria:

• < 18 or > 100 years of age
• Pregnant or breastfeeding
• Blue dye allergy
• Cosmetic allergy
• History of primary lymphedema
• Prior breast augmentation