Mohs' micrographic surgery using frozen sections alone may be unsuitable for detecting single atypical melanocytes at the margins of melanoma in situ

Abstract

Using these histological criteria, micrographic surgery with frozen sections alone is unreliable in the excision of MIS.

Surgical Margins for Lentigo Maligna and Lentigo Maligna Melanoma

“…Mohs micrographic surgery is the best known technique of margin control; however, visualization of atypical melanocytes on frozen sections can be extremely challenging for the Mohs surgeon and/or pathologist. Cohen et al 27 and Barlow et al 28 reported sensitivities of only 73% and 59%, respectively, combined with specificities of only 68% and 81%, respectively, in frozen sections of LM and LMM. In contrast, Zitelli et al 29 reported sensitivity and specificity of 100% and 90%, respectively, in the diagnosis of melanoma on frozen sections.…”

Management of Lentigo Maligna and Lentigo Maligna Melanoma With Staged Excision

“…Other studies looking at LM and LMM have found sensitivities of 59% to 73% and specificities of 68% to 81%. 2,31 We understand that the major advantage of MMS surgery over our described method is that Mohs surgery ideally allows for examination of 100% of the margin. For margin interpretation, our described method might thus be expected to have a lower sensitivity (ability to pick up tumor cells when they are truly present), but not specificity, compared with MMS.…”

“…26,31,33 With beveled sectioning, normal melanocytes may appear enlarged, and frozentissue processing causes keratinocyte vacuolization and loss of the melanocyte retraction artifact used to distinguish the 2 cell types. Because of different comparison techniques, studies addressing the sensitivity and specificity of frozen sections for LM are difficult to compare.…”

“…It is well documented that the peripheral margins of LM found in areas of chronic sun damage are difficult to interpret (true LM vs "background" sun-induced melanocyte atypia). 31,32 The dermatopathologist who read the slides for this study believed that it is easier to evaluate the margins by following the tumor's "evolving" architecture from the center in a centrifugal fashion rather than examining only the peripheral edge, as is done with traditional MMS en face sectioning. When only an en face margin is examined, it can be difficult to tell the difference between scattered baseline atypical melanocytes and the single melanoma cells that taper out toward the periphery of a lesion of LM.…”

Presentation, Histopathologic Findings, and Clinical Outcomes in 7 Cases of Melanoma In Situ of the Nail Unit

“…16,17 However, other paired comparisons of frozen sections vs paraffin embedding have demonstrated increased diagnostic accuracy with permanent techniques. [18][19][20] Currently, our dermatologic surgery division uses frozen sections, occasionally with immunohistochemi- …”