Dermatologic Surgery
Histologic evaluation of lentigo maligna with permanent sections: Implications regarding current guidelines,☆☆,

https://doi.org/10.1067/mjd.2002.124085Get rights and content

Abstract

Background: Obtaining clear margins of resection of lentigo maligna (LM), a subtype of melanoma in situ, from sun-damaged skin of the head and neck continues to be a surgical challenge. The margins may be uncertain both clinically and histologically, causing difficulty in determining the surgical excision perimeter. Objective: We sought to determine whether the current National Institutes of Health consensus conference (1992) recommendation of 5-mm margins is adequate for the removal of LM and to evaluate at what stage tumor-free margins are ultimately attained by using polygonal, staged excisions. Methods: Ninety-two cases of LM were evaluated and treated in a university tertiary care setting. Straight-edge polygonal resections in a staged fashion of LM variants of MIS were evaluated by means of permanent serial histopathologic sections. Each stage of resection used a 5-mm margin. Specimens were color-coded and mapped. Any sites of tumor at resected margins were identified by a dermatopathologist and noted on the map of the excised specimen. Positive margins and areas with markedly atypical melanocytes were further resected, color-coded, mapped, and evaluated as previously described until margins free of tumor were attained. Results: The patient distribution was 37% female and 63% male, with ages ranging from 24 to 100 years (median age, 70 years). Sixty-nine patients had a biopsy-proven diagnosis of LM involving the head and neck (75%), and 23 patients (25%) had LM elsewhere. Thirty-nine patients (42%) were tumor-free after one stage, 25 (27%) required 2 stages, 14 (15%) required 3 stages, 6 (7%) required 4 stages, and 8 (9%) needed 5 or more stages to achieve tumor-free margins. The central portion of the submitted polygonal excisions revealed an invasive component in 16% of cases. Conclusions: Use of polygonal perimeter excisions with serial histopathologic permanent sections in a staged fashion is an accurate and thorough method of evaluating and treating LM. This study demonstrates that the standard recommendation of 5-mm margins is adequate in less than 50% of cases and reiterates the need for the careful evaluation of peripheral margins in LM. Because an invasive component can be present and would alter recommended surgical depths and margins, all of the tumor should be submitted at the first stage rather than peripheral margins only. (J Am Acad Dermatol 2002;47:743-8.)

Section snippets

Methods

All patients were evaluated at the University of Utah Health Sciences Center, Department of Dermatology, from July 1, 1994, to October 15, 2000. Two Mohs surgeons and one Mohs fellow performed the excisions. Two board-certified dermatopathologists interpreted the slides. Ninety-two consecutive patients with a diagnosis of MIS, LM type, were enrolled. Demographic data demonstrated ages ranging from 24 to 100 years (median age, 70 years) with 37% female and 63% male. All patients were Caucasian.

Results

In the group of 93 patients studied, 69 (75%) of the tumors were found on the head and neck, and 23 (25%) were found elsewhere. Sites on the head and neck, in decreasing frequency, were the cheeks, nose, forehead and temple, ears, neck, scalp, and chin. Of the 25% of the remaining lesions in sites other than the head and neck, 50% were on the extremities, 42% were on the trunk, and 8% were in acral areas. With staged excisions, 39 (42%) were clear after one stage, 25 (27%) required 2 stages, 14

Discussion

Use of permanent sections removed in straight-edged polygons around LM is a reliable and reproducible method for identifying tumor-free margins. Submission and evaluation of the center portion may reveal an otherwise unsuspected invasive component. Many approaches to removal of LM in a staged manner have been reported. Such approaches vary in slight ways in both philosophy and technique but have evolved to achieve the same goal: verifying clear peripheral and deep margins for LM before a repair

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    Funding sources: None.

    ☆☆

    Conflict of interest: None.

    Reprint requests: John W. Gerwels, MD, University of Utah, Department of Dermatology, 50 N Medical Dr, Salt Lake City, UT 84132.

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