Imaging in Oncology: The Role of Lymphoscintigraphy in Staging

Claudia G. Berman, MD
Radiology Services
H. Lee Moffitt Cancer Center & Research Institute

Case Description:

Fig 2. Lymphoscintigram of left lateral chest. The open arrow shows the injection site. The solid arrow shows the sentinel lymph node in the left axilla. The unmarked uptake between the two arrows represents an "in-transit" node.

Answer:

All three choices are correct. Lymphoscintigraphy (LS) provides a means to depict the unique drainage patterns of patients with clinical stage I malignant melanoma. The technique entails an injection of a small amount of radiolabeled particles intracutaneously surrounding the skin lesion. The particles are transported within the draining lymphatics and accumulate in the lymph nodes of the draining lymph node basins. Approximately 20% of patients with clinical stage I malignant melanoma will demonstrate regional lymphadenopathy.[1]

LS has been used as a modality for locating lymph nodes at risk for harboring subclinical metastatic disease. In a study of 135 patients,[2] a high rate of discord (overall 41%) was found between the drainage patterns predicted by historical, anatomic guidelines and those revealed by LS. As a result, surgical management was redirected in 33% of patients, thereby establishing the usefulness of LS for defining clinically relevant lymphatic drainage patterns.

In-transit lymph nodes are detected between the lesion and the draining regional lymph node basin in a small percentage of cases (less than 5%). The anecdotal experience at our institution demonstrates cases of metastatic disease in in-transit lymph nodes with and without metastatic disease in the draining lymph node basin. These in-transit lymph nodes should be excised for optimal treatment and are detected only on preoperative LS. (Note the in-transit node identified by the solid arrow in Fig 2).

The sentinel lymph node (SLN) is the first draining node of a lymph node group. Reintgen et al[3] have shown that a negative SLN is predictive of a histologically benign lymph node basin. In a recent study conducted at our center,[4] the site of the SLN was marked preoperatively on the external skin at the time of LS, and a hand-held gamma probe was then used to identify the lymph nodes at the time of dissection. SLNs were identified in 83.5% of patients by LS alone and in 96% when vital blue-dye staining was used adjunctively. Microscopic metastasis was found in 15% of these clinically uninvolved SLNs.

References

1. Mastrangelo M, Baker AR, Katz HR. Cutaneous melanoma. In: DeVita VT Jr, Hellman S, Rosenberg SA, eds. Cancer Principles and Practice of Oncology. Philadelphia, Pa: JB Lippincott; 1982:1392.

2. Berman CG, Norman J, Cruse CW, et al. Lymphoscintigraphy in malignant melanoma. Ann Plast Surg. 1992;28:29-32.

3. Reintgen D, Cruse CW, Wells K, et al. The orderly progression of melanoma nodal metastases. Ann Surg. 1994;220:759-767.

4. Albertini JJ, Cruse CW, Rapaport D, et al. Intraoperative radiolymphoscintigraphy improves SLN identification in melanoma patients. Ann Surg. 1995. In press.

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