lymphoscintigraphies performed during sentinel lymph node ( sln ) mapping and biopsies in breast cancer have discovered lymphatic extra - axillary drainage in 20 - 27% of cases . extra - axillary nodes most often located are : ipsilateral internal mammary chain ( imc ) ( 17% ) , intra - mammary ( 3% ) , supraclavicular ( 2% ) and interpectoral ( 2% ) nodes . contralateral axillary drainage is an unexpected finding that is a source of controversies in the management of these patients.[310 ] this situation is more exceptional when there is not prior breast surgery,[710 ] especially when internal mammary chain drainage is associated . a 48-years - old woman with no prior surgery of breast or axilla was diagnosed of breast ductal carcinoma in retroareolar region of the right breast with size of 2 cm . lumpectomy and sentinel lymphatic node ( sln ) biopsy was suggested . the day prior to surgery , a lymphoscintigraphy was performed with peritumoral injection of two doses of 74 mbq of technetium-99m - nanocolloid ( volume of 0.1 ml ) each one . planar images were acquired at 120 min of injection , including chest in anterior and lateral projections . we acquired images of 3 min in a 256  256 matrix using a planar source of cobalt-57 in anterior projection and an anatomical point source of tc99 m in order to delineate the body shape and locate the nodes . the images showed drainage to ipsilateral axillary nodes , ipsilateral imc and contralateral axillary nodes [ figure 1 ] . in the left we show anterior image of lymphoscintigraphy after 2 peritumoral injection of tc-99m - nanocolloid in the retroareolar region of right breast . bilateral axilla and ipsilateral ( internal mammary chain ) imc drainage are depicted with at least , 3 nodes in right axilla , 2 in imc and only one in left axilla . in the right upper quadrant , in the left lateral projection we can see tracer injection activity in the breast and the only contralateral axillary node . in the right lower quadrant , right lateral projection shows activity in the breast and in the main axillary node in the operating room , lumpectomy and sln biopsy of the three territories were performed . frozen section and subsequent 2 mm step sections of the paraffin embedded nodes did not reveal metastases in any of the lymph nodes . the patient was treated with chemotherapy , radiotherapy and hormone therapy and no significant complications were observed . there are several works , which show patients with contralateral axillary drainage but with prior history of surgery due to breast cancer , mammoplasty , axillary dissection due to melanoma or excissional biopsy , etc . , these abnormal drainages probably would be caused by surgical disruption of the physiological lymphatic pathway , and the clinical implications of them are different to these cases with no prior surgery procedures in the breast or axilla . we have found only four articles with contralateral axillary drainage and no prior surgery in breast or ipsilateral axilla.[710 ] simultaneous imc nodes were not found in any of them . in two cases , the lymphoscintigraphy showed bilateral drainage and all nodes were selected as sentinel and excised . histological studies did not reveal tumor spread in all nodes and did not impact in the management of the patients . tumor spread of a contralateral axillary lymph node is considered to be due to distant metastasis ( m1 ) by mean of conventional diagnosis procedures , or due to the presence of other occult primary cancer in contralateral breast . differentiation between a systemic metastatic disease and an atypical lymphatic spread would be of great interest in the prognosis and management of these patients . lymphoscintigraphy is the only procedure capable of separating these clinical situations , because extra - axillary lymph nodes are not detectable using blue dye alone.[79 ] metastases to a contralateral axillary lymph node reflect the lymphatic drainage of the tumor as seen on lymphoscintigraphy . so , the patient should be considered to have a node positive and not metastatic ( m1 ) disease . most lymph passes from the breast along interlobular vessels to the subareolar plexus and follows the veins of the breast to the axilla ( 75% ) . lymph from the medial part of the breast , in addition to the axilla , drains into the parasternal lymph nodes . some authors think that lymph from the skin of the breast may pass to the abdominal wall and opposite breast through the subdermal plexus as it is seen in melanoma , but retrosternal crossover to the contralateral side could be the pathway if there is internal mammary involvement . we think that in our patient , the lymph could have passed through the retrosternal pathway to the contralateral side because the tumor was located deep in the retroareolar region as we can see in the figure 1 . krause and colleagues described a case , which showed that the only metastatic lymph node was the contralateral axillary sentinel node , a finding , which may impact on adjuvant therapy , if this situation were ignored . , showed a patient with bilateral axillary drainage in which both axillary nodes were positive ; ipsilateral lymphadenectomy was performed and four more lymph nodes were removed from the left ( contralateral ) axilla . all nodes were free of metastases . a complete level i and level ii axillary lymph node dissection was not performed on the contralateral side because of concerns about bilateral lymphedema . probably , this would be the right choice and could be implemented selecting the contralateral nodes by mean of manual exploration removing all nodes enlarged and/or hardened.[1113 ] we think , as the same of carmon , et al . , that all  ectopic  nodes should be considered as sentinel nodes and must be biopsied to reach the most complete staging as possible . the knowledge of extra - axillary lymph nodes containing metastases may lead to better selection of patients for various adjuvant treatments such as radiotherapy to extra - axillary sites of metastatic sentinel lymph nodes or alteration of chemotherapy modalities if an extra - axillary sentinel node is the only metastatic lymph node . in our opinion , lymphoscintigraphy should be always used in addition to or instead of dye methods for lymphatic mapping . the only way to find a metastasis in a contralateral axillary lymph node arose from the primary carcinoma in the opposite breast is to use lymphoscintigraphy and perform sentinel node biopsy ( snb ) of contralateral nodes if founded . the distinction between node - positive and systemic metastatic disease is important considering the different treatment objectives and modalities for node positive versus metastatic breast cancer .