There are certain large tumors where it is clear that Mohs is not appropriate, Dr. Lin said. He said the Mohs approach should be avoided in the setting of “extensive” lesions involving deep structures and in the setting of invasive melanoma, except with lentigo melanoma and in situ melanoma.
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November 2013Sentinel Lymph Node Biopsy
Cecelia Schmalbach, MD, MS, co-director of the University of Alabama at Birmingham’s Cutaneous Head and Neck Oncology Board, said SLN biopsy is crucial in finding occult disease. It’s a minimally invasive technique to identify the “first echelon” lymph nodes that are mostly likely to harbor occult nodal metastasis.
She emphasized that it is only a staging tool, though, helping to identify who might benefit from adjuvant therapy and to spare patients without nodal disease the morbidity of a formal neck dissection. She noted that more data is needed to determine whether it’s actually therapeutic or could impact survival.
If a patient has a negative SLN biopsy, the current National Comprehensive Cancer Network guidelines say, there’s no need for formal neck dissection, but the patient should be followed clinically. “This is important, because anywhere on the order of 4 to 8 percent of patients will develop a second melanoma and that could be as late as 10 years out from their initial treatment,” she said. SLN for squamous cell carcinoma hasn’t yet been established, but she said that the data so far is “encouraging.”
Carol Bradford, MD, chair of otolaryngology at the University of Michigan, said the issue of whether or not to treat using the Mohs approach is crucial. “We have to consider how we are going to address the neck early enough in all of these patients such that the patients don’t suffer poor outcome due to regional failure,” she added. “Obviously, if patients have had a wide excision by the Mohs surgeon, the opportunity to do any sentinel lymph node biopsy to stage the regional nodal basin is gone.”
Cases of high-risk squamous cell carcinoma patients present a special challenge. “We can watch and wait, but we do know that that’s not a very effective strategy for picking up regional disease early enough to not have it be a big problem,” said Dr. Bradford. “I encourage you to consider strategies at the outset as to how to manage that regional basin.”
As for other malignancy types, serial sectioning and immunostaining are important for detecting small tumor burdens in sentinel nodes.