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Editorial |
1 Department of Dermatology, Massachusetts General Hospital, Boston, USA
2 Johns Hopkins Medical Institutions, Surgery, Oncology and Dermatology, Baltimore, USA
3 Professor of Surgery, Oncology and Dermatology, Johns Hopkins Medicine, 600 N. Wolfe Street; Osler 624, Baltimore, MD 21287, USA
Correspondence: Address correspondence and reprint requests to: Charles M. Balch; E-mail: balchch{at}jhmi.edu
The publication of "Melanoma Biopsy Method and Positive Margins" by Stell et al. in this issue of the Annals provides the opportunity to highlight approaches to the biopsy of cutaneous melanoma. The first issue is whether an incisional biopsy into a melanoma could disrupt melanoma cells that would then metastasize. The generally accepted practice in some northern European countries up until a decade or so ago was that suspected melanomas were excised with wide excision margins under general anesthesia to avoid the potential spread of melanoma by either cutting into the tumor or otherwise dislodging tumor cells by the injection of local anesthetic. In 1985, Lederman and Sober provided data that demonstrated no adverse effect on prognosis from performing a partial biopsy of cutaneous melanoma (incisional or punch biopsy vs. excisional biopsy) after correcting for thickness.1 Subsequent multivariant analyses have not demonstrated an independent effect of biopsy on outcome. Thus, the most important principle here would be to promptly establish the diagnosis of melanoma by whatever biopsy type is appropriate for the specific lesion at hand followed promptly by definitive therapy for that specific melanoma.
The second issue concerns the adequacy of each type of biopsy for establishing a correct diagnosis of melanoma and in accurately determining micro-staging. There is no question that total excisional biopsy with narrow margins provides the pathologist with the ideal specimen for determining the above items and this has been recommend in published guidelines.2 In what situations may partial biopsy be inadequate in establishing the diagnosis of cutaneous melanoma?
The article by Stell et al. also addresses an additional issue of importance which is the frequency with which partial biopsy may result in underestimating the microstage (as measured by thickness and level of invasion), leading to possible under-treatment for the patient. In this study, specimens were divided by biopsy technique (excisional vs. punch vs. shave). As would be expected, punch biopsies had a higher frequency of positive margins, since these biopsies are typically removing only a portion of the tumor. The exception would be what is termed a "punch excision" where the intent is to remove the entire lesion and with this form of biopsy where the punch encompasses the entire specimen margins may be negative but close. Usually, a 6 mm punch trephine is utilized so the majority of the lesion can be removed and there is less chance for fragmentaion of the lesion which may occur with a small punch biopsy trephine. When performing a punch biopsy, the most elevated portion of the lesion is sampled which usually correlates to the thickest portion of the tumor.4 In flat lesions the darkest portion is typically recommended for biopsy. Stell et al. note that shave specimens have a significantly higher percentage of positive deep margins than punch or excisional specimens. This is likely related to the type of shave biopsy performed. Shave biopsies fall into two categories: "tangential" where the biopsy specimen is relatively superficial and the plane of the scalpel is brought directly below the specimen parallel to the surface, and "deep shave" biopsy or a "saucerization" biopsy where the lesion is more or less scooped out from the skin. The former type of biopsy would yield a higher rate of positive deep margins with thicker lesion than the deep or saucerization type of biopsy. It is important to note that shave biopsies are the most frequent type of specimen nationally submitted to dermatopathology labs for the evaluation of pigmented lesions. Stell et al. point out the 22% of their shave biopsy specimens had positive deep margins which compromised the ability to properly stage these patients. However, since the vast majority of these lesions were not thick ones, (since shave biopsies were most likely done on thin lesions) a microstaging change that would change the recommended therapy only occurred in 2% of the patients.
Nevertheless, a shave biopsy with a positive deep margin may cause the physician, and the patient, to recommend performing a lymphatic mapping and sentinel node procedure because of the uncertainly of the thickness and level measurements, even for lesions measuring < 1.0 mm in thickness. This might result in unnecessary cost and morbidity for a procedure that would otherwise be avoided if a proper biopsy was performed that enabled accurate microstaging of the melanoma.
While we strongly recommend a full thickness excisional biopsy with narrow margins whenever possible, an incisional biopsy can be acceptable (especially for larger lesions) when the clinical suspicion for melanoma is high. On the other hand, it is apparent from the practice nationwide and from the article from Stell et al., that in some instances the correct diagnosis can be established via partial biopsy but that the ability to accurately microstage the lesion and make recommendations about a sentinel node staging procedure may be compromised. As a result, unnecessary sentinel node procedures may be performed. A tangential biopsy should be avoided, but a deep "saucerization" biopsy may be satisfactory when the lesions are flat and the suspicion for melanoma is not high.
Received for publication November 13, 2006. Accepted for publication November 15, 2006.
REFERENCES
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