The Emergence of Rapid Counter Immunostaining in the Controlled Narrow Excision of Malignant Melanoma—How We Do It

Mohs Micrographic Surgery (MMS) is widely employed in the treatment of non-melanoma skin cancer and is a preferred treatment for many cutaneous malignancies, particularly in high risk locations and tumors [1,2]. It has also been used in the narrow excision of malignant melanoma with local control rates equivalent to standard margins [3]. It has gained acceptance in the treatment of noninvasive melanoma where standard 0.5 cm margins may be inadequate for local control [4]. The frozen section processing used in MMS has been assumed by some to be inadequate in assessing melanocyte populations or residual melanoma within excision margins. This difficulty has likely led to a majority of surgeons with fellowship training to process margins with slow, permanent hematoxylin and eosin sections (“slowmohs”) or to simply resort to standard 0.5, 1.0, or 2.0 cm margins with traditional excision and outside pathology confirmation of clear margins. A recent survey of practicing fellowship-trained Mohs surgeons revealed roughly one-third (35.9%) of Mohs surgeons felt comfortable interpreting MART-1 immunostains, and far fewer were actually performing immunostains in their labs [5]. Some Mohs surgeons currently refer melanoma to a colleague experienced in processing and reading melanoma with available rapid immunostaining. The development of rapid immunohistochemistry, which can be implemented into a traditional frozen section laboratory, has greatly improved the ease of interpreting margins in the excision of melanoma. Although the process is considerably more complicated than staining with H&E or Toluidine Blue (T-Blue), it easily falls within the skill-set and equipment of most busy frozen section laboratories. The additional cost of biologic reagents may be fully recovered by proper billing of immunohistochemical laboratory work and interpretation of slides.