Case 1 Normal Drainage Pattern

A 53-year-old woman was referred with a suspicious-looking mole on the sole of the right foot. The lesion had been present for many years but had recently changed in appearance: it had increased in size and become darker in color. Excision with a narrow margin was performed. Histological examination revealed a nodular melanoma with ulceration (Clark level IV, Breslow thickness 5.0 mm). Wide local excision and sentinel node biopsy were planned.


A dose of 50.2 MBq (1.4 mCi) technetium-99m (99mTc)-labeled nanocolloid (Na-nocoll; Amersham Cygne, Eindhoven, the Netherlands) in a volume of 0.20 mL was injected intradermally around the biopsy scar. A radioactive flood source was placed behind the patient to outline the body contour [1]. The early images showed two lymphatic vessels running to two adjacent lymph nodes in the groin (Fig. 1). These nodes were marked on the skin with indelible ink. Several other ''hot'' spots higher up were visualized in a later phase. The study was reported

Figure 1 The early anterior view shows two lymphatic vessels and two sentinel nodes (arrows). Two second-tier nodes and a third-tier node are depicted higher up.

as showing two sentinel (first-tier) nodes with direct drainage from the injection site and several second-tier nodes higher up.


The patient was taken to the operating room the next day. One milliliter of patent blue dye (Bleu Patente V; Guerbet, Aulney-Sous-Bois, France) was administered around the biopsy site on the right foot when the patient was anesthetized, prepared, and draped. The injection site was gently massaged. The skin of the inside of the leg was massaged with strokes directed toward the groin.

Ten minutes later, a 3-cm incision was made between the skin marks placed by the nuclear medicine physician. Underneath Scarpa's subcutaneous fascia, two blue lymphatic vessels were identified. The vessels were dissected and followed to two adjacent blue nodes. Other blue ducts emerged from the nodes and ran in a cranial direction. The nodes were freed from the surrounding fat. Blood vessels and lymphatic vessels to and from the nodes were ligated and divided.

The nodes were examined with a gamma-ray detection probe (Neoprobe 1500; Neoprobe Corporation, Dublin, OH) both in the wound and after excision, and were confirmed to contain 99mTc. The nodes were submitted to the pathologist. The wound was then scanned with the probe for other hot nodes, but none was found, with the exception of the second-tier nodes that were known to be present further up the groin. The subcutaneous fat was approximated to obliterate the biopsy cavity, and the skin was closed. The operation was continued with wide local excision of the biopsy site. No completion inguinofemoral node dissection was performed.


Hematoxylin and eosin (H&E) staining and immunohistochemistry (S-100, HMB-45) revealed no melanoma deposits in the two sentinel nodes.


This patient demonstrates a typical drainage pattern. A melanoma on the leg usually drains to two sentinel nodes caudally from Poupart's ligament, whereas a melanoma on the arm drains more often to a single sentinel node in the axilla. Drainage on the trunk and in the head-and-neck area is more difficult to predict.

Lymphoscintigraphy nicely demonstrates the lymphatic vessels and the nodes. It is important that the surgeon reviews the images together with the nuclear medicine physician because they are not always as easy to interpret, as in this case. A thorough review of the images ensures that the surgeon knows how many nodes to expect and where to look for them.

The blue dye technique was used to identify the nodes in this patient, and the probe was used for confirmation. A surgeon obtains the best results with both techniques in the repertoire [2].


1. Valdes Olmos RA, Hoefnagel CA, Nieweg OE, Jansen L, Rutgers EJTh, Borger J, Horenblas S, Kroon BBR. Lymphoscintigraphy in oncology: a rediscovered challenge. J Eur J Nucl Med 1999; 26(Suppl):S2-S10.

2. Nieweg OE, Jansen L, Kroon BBR. Technique for lymphatic mapping and sentinel node biopsy for melanoma. Eur J Surg Oncol 1998; 24:520-524.

Case 2: Definition of a Sentinel Node: Lymphatic Vessels and Time of Visualization

A 56-year-old man presented with a melanoma in the right flank. A diagnostic excision with a narrow margin was performed. Histological examination showed a superficial spreading melanoma (Breslow thickness 1.7 mm, Clark level III).


A dose of 56 MBq (1.5 mCi) 99mTc-nanocolloid in a volume of 0.25 mL was injected intradermally at four sites close to the biopsy scar on the right-flank. Early lymphoscintigraphy images were obtained 20 minutes later and showed drainage to a single sentinel node in the right axilla (Fig. 2). Two second-tier nodes were visualized more cranially.

The anterior view that was obtained 2 hours after the injection showed the same pattern. However, the late lateral view showed a second lymphatic vessel going to a second node that is situated somewhat more posteriorly. The conclusion was that there were two first-tier (sentinel) nodes and two second-tier nodes.


The operation was performed 1 day after the lymphoscintigraphy. A quantity of 1 mL of patent blue dye was administered in two doses on either side of the biopsy scar in the right flank. Ten minutes later, a 5-cm transverse incision was made along the lower hair line in the right axilla. A blue duct was identified underneath Scarpa's fascia and traced to a blue node. The gamma-ray detection probe confirmed that the node was radioactive. A second blue duct was identified somewhat more posteriorly. This duct was dissected to a second blue radioactive node. Both sentinel nodes were removed. No other blue ducts were observed. Scanning the wound with the probe revealed increased uptake in the two second-tier nodes, but these were not pursued.

Figure 2 The early lymphoscintigraphy images depict one sentinel node in the right axilla. Two second-tier nodes are visible higher up. The late anterior image gives us the impression that there is one lymphatic vessel going to one sentinel node. The lateral view makes it clear that there are two nodes on a direct drainage pathway.

Figure 2 The early lymphoscintigraphy images depict one sentinel node in the right axilla. Two second-tier nodes are visible higher up. The late anterior image gives us the impression that there is one lymphatic vessel going to one sentinel node. The lateral view makes it clear that there are two nodes on a direct drainage pathway.

Pathology and Follow-Up

Frozen sectioning, H&E staining, and immunohistochemistry (S-100, HMB-45) of the two nodes revealed no metastatic disease. No axillary node dissection was performed. The patient remained free of disease 4 years later.


The dynamic scintigraphy images depict the lymphatic vessels and show the surgeon where to expect them. This case touches on an important point concerning the definition of a sentinel node. Some investigators in the field of nuclear medicine define the sentinel node as the first lymph node that becomes visible on the lymphoscintigraphy images [1]. Although the first node that is depicted is a sentinel node, this definition does not acknowledge the fact that sometimes there are more sentinel nodes than just one. Sometimes there are two lymphatic vessels originating in the region of the primary tumor running to two different lymph nodes. One of the two may be depicted on the scintigraphy images before the other. But that does not imply that the other node is not a sentinel node. Both nodes are on a direct drainage pathway, and tumor cells can travel through either duct and go to either node. Both should be collected and examined by the pathologist. Receiving drainage directly from the primary tumor site is what makes a lymph node a sentinel node [2,3]. There are several explanations for the fact that one node receives less lymph flow than another. One of the reasons is that the flow to that particular node is hampered by metastatic disease.

Another point illustrated by this cases is that lymphoscintigraphy with only one view is not good enough. A sentinel node may be located behind another sentinel node, and as a result only one hot spot is depicted.

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