What is selective sentinel lymph-node lymphoscintigraphy and biopsy (SSLNB), and how is it used in the evaluation of Merkel cell carcinoma (MCC)?

Updated: Jan 18, 2019
  • Author: Arjun S Joshi, MD; Chief Editor: Arlen D Meyers, MD, MBA  more...
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SSLNB is effective in the evaluation of regional micrometastatic disease in cutaneous melanoma.

Colloids labeled with technetium-99m (99mTc) are intradermally injected into the primary excision site. A gamma camera with a large-field view is used to localize lymphatic drainage to sentinel nodes in the regional nodal basins. The identified sentinel nodes can be tattooed before surgery.

Intraoperative localization of the sentinel nodes can also be performed in a similar manner by using a hand-held gamma counter.

As an alternative, vital blue dyes can be injected just before the operation to localize the sentinel nodes. During surgery, pale-blue staining marks afferent lymphatics, which are followed to the sentinel nodes.

A meta-analysis of patients with MCC who were undergoing SSLNB revealed that two thirds had negative biopsy results and that 97% remained disease-free 7 months after biopsy. Of the third who had positive biopsy results, 33% had some form of local, regional, or systemic recurrence at 12 months.

SSLNB positivity appears to be correlated with an increased short-term risk of recurrence or metastasis.

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