Atypical melanocytic nevi

Dysplastic nevus part II: Dysplastic nevi: Molecular/genetic profiles and management

Dermatologists frequently see patients with clinically atypical nevi and dermatopathologists interpret histologically dysplastic nevi on a near-daily basis, but there is great variability in the definition and management of such lesions. This part of the CME review focuses on information published since the previous comprehensive review (2012), with emphasis on molecular and genetic attributes of histologically dysplastic nevi and clinical management.

Predictive Value of Positive Margins in Diagnostic Biopsies of Dysplastic Nevi

Dysplastic nevi (DN) are common and controversial and the best choice for management of DN after diagnosis is not always clear. The presence of positive margins found on diagnostic biopsy is used by many dermatologists when deciding whether to re-excise these lesions. In order to quantify the predictive value of positive margins in diagnostic biopsies of DN, we performed a review and analysis of the concordance between the histological findings of biopsies and their subsequent excisions. A total of 122 pathology reports from diagnostic biopsies of DN with nevus cells present at the tissue margin were reviewed. Within this sample, 68 total postbiopsy excisions had been performed. The excisional pathology reports were reviewed for the presence of residual or recurrent nevus cells. Residual nevus cells were reported in 29 of 63 available excisional pathology reports illustrating a positive predictive value (PPV) of positive margins in diagnostic biopsies of DN of 46.0%. We present this value along with PPVs from the very few existing similar studies. The quantified predictive value of positive margins in diagnostic biopsies is useful information for providers who must make decisions regarding the best treatment options for patients with DN. The low PPV of positive margins lends further evidence that DN of moderate severity or less may simply be monitored.

Re-biopsy of partially sampled thin melanoma impacts sentinel lymph node sampling as well as surgical margins

AIM

To assess the impact of re-biopsy on partially sampled melanoma in situ (MIS), atypical melanocytic proliferation (AMP) and thin invasive melanoma.

MATERIALS & METHODS

We retrospectively identified cases of re-biopsied partially sampled neoplasms initially diagnosed as melanoma in situ, AMP or thin melanoma (Breslow depth ≤0.75 mm).

RESULTS & CONCLUSION

Re-biopsy led to sentinel lymph node biopsy (SLNB) in 18.3% of cases. No patients upstaged from AMP or MIS had a positive SLNB. One out of nine (11.1%) initially diagnosed as a thin melanoma ≤0.75 mm, upstaged with a re-biopsy, had a positive SLNB. After re-biopsy 8.5% underwent an increased surgical margin. Selective re-biopsy of partially sampled melanoma with gross residual disease can increase the accuracy of microstaging and optimize treatment regarding surgical margins and SLNB.

The management of dysplastic naevi: a survey of Australian dermatologists

BACKGROUND/OBJECTIVES

The management of dysplastic naevi based on histopathological grading is a contentious issue. Comprehensive management guidelines are lacking and the approach taken varies between clinicians. The authors sought to understand how Australian dermatologists approach the management of biopsy-proven dysplastic naevi, and the impact of grading of dysplasia upon this management.

METHODS

In total, 547 Fellows of the Australasian College of Dermatologists were surveyed and 218 responses were collected (40% response rate).

RESULTS

Although all dermatologists surveyed would re-excise an incompletely removed severely dysplastic naevus, opinion was divided over whether to treat such a lesion as an in situ melanoma or a dysplastic naevus, with 55% of respondents using a 5-mm margin and the remainder opting for narrow margin re-excision. When the same lesion was reported to be clear of margins by 1 mm after biopsy and the clinical suspicion for melanoma was high, 44% would re-excise with a 5-mm margin.

CONCLUSIONS

The approach of Australian dermatologists to the management of dysplastic naevi varies between clinicians, reflecting the problems raised by the validity of histopathological grading.

Dysplastic (or Atypical) Nevi Showing Moderate or Severe Atypia With Clear Margins on the Shave Removal Specimens Are Most Likely Completely Excised

BACKGROUND

Dysplastic nevi (DN) are graded by their degree of atypia into 3 categories of mild, moderate, and severe. In many practices, DN with moderate or severe atypia are generally excised regardless of the status of the shave specimen margins.

OBJECTIVE

With a new approach toward the margins on the shave removal specimens (SRS), the goal herein is to assess whether the shave removal procedure can sufficiently remove DN with moderate or severe atypia.

METHODS

A total of 426 SRS diagnosed with DN showing moderate or severe atypia between January and December 2015 along with their post-shave excision specimens were reviewed. Based on the author's experience, clear or negative margins on the SRS were defined as neoplastic melanocytes confined within >0.2 mm of the lateral and deep specimen margins. The biopsy specimens were accompanied by Melan-A highlighting the subtle neoplastic cells.

RESULTS

With a negative predictive value (NPV) of 98.4% (confidence interval: 97.2% to 100%, P < .001), DN showing moderate or severe atypia with clear margins are most likely removed by the shave procedure.

CONCLUSION

Routine excision of DN showing moderate or severe atypia with clear margins on SRS is not necessary. Regular surveillance is sufficient.

The role of observation in the management of atypical nevi

OBJECTIVE

The definition and management of the atypical nevus remains a controversial issue. Some believe that atypical nevi are common variants of benign melanocytic nevi while others believe they are lesions intermediate between benign melanocytic nevi and melanoma. Therefore, the question of whether or not partially removed atypical nevi should be re-excised with clear margins in order to prevent their evolution into melanoma remains unanswered. Although studies have shown that most atypical nevi will never progress into melanoma, re-excision, when biopsy margins are positive, is commonly practiced. We argue that re-excision in such cases is not necessary.

METHODS

Our cohort study includes 55 previously biopsied atypical nevi that were not re-excised and which were followed for at least 5 years with a mean follow up time of 6.12 years.

RESULTS

The experimental group included 26 atypical nevi whose biopsy revealed at least one involved margin. The control group included 29 atypical nevi whose biopsy revealed clear margins. No melanomas were observed to arise in association with a pre-existing atypical nevus in either the experimental or control group during the follow-up period.

CONCLUSIONS

The results of our study support observation as a safe alternative to re-excision for incompletely removed atypical nevi. A large prospective study with longer follow up would be necessary to better answer the question of how often atypical nevi evolve into melanoma and over what time period this occurs.

Dysplastic naevi: to shave, or not to shave? A retrospective study of the use of the shave biopsy technique in the initial management of dysplastic naevi

The management of dysplastic naevi is a controversial subject. This study sought to assess the usefulness of the shave biopsy technique in the initial management of dysplastic naevi, and to demonstrate the advantages over the punch biopsy technique. We report a retrospective observational study of histopathology specimens examined in one histopathology practice over a 14-month period. Patients who had a clinical diagnosis of 'dysplastic naevus', which had initially been biopsied using either a shave or punch biopsy, and then followed up with a full-thickness elliptical excision, were included in the study. Histopathological concordance between the shave and punch biopsy specimens and their respective follow-up elliptical excisions was compared. We found that 21 of 22 (95.5%) shave biopsies were concordant with their respective excision specimens, and that 29 of 41 (70.7%) punch biopsies were concordant with their respective elliptical excision specimens. Of the shave biopsy specimens reviewed, 66% showed that the dysplastic naevi were completely excised with the initial biopsy, compared with 21.2% of the punch biopsy specimens. These findings confirm that shave biopsies provide accurate diagnostic information in the assessment of dysplastic naevi. Shave biopsies enable the entire lesion to be submitted for histopathological assessment, improving the chances of an accurate diagnosis.

The dilemma of the dysplastic nevus

There are few areas in dermatology that provoke as much controversy as dysplastic nevus. Over the past decade, there have been significant strides made in terms of understanding the biology and etiology of the lesion. Distinct and reliable clinical and histologic features have been delineated. In this article, the management of patients with dysplastic nevi and the role for dermoscopy, photographic surveillance, genetic mapping and counseling, chemoprevention, and nevi removal are discussed.

Deep shave excision of macular melanocytic nevi with the razor blade biopsy technique

BACKGROUND

Shave excision is an established surgical method for removing benign skin lesions for cosmetic and functional reasons. Usually superficial shave excision is performed with a common scalpel blade for the removal of papular nevi. However, there is little known about deep shave excision of macular melanocytic nevi with the razor blade technique.

OBJECTIVE

The present study was undertaken to evaluate the cosmetic outcome of deep shave excision of macular melanocytic nevi with the razor blade technique. Moreover, its potency for sufficient removal of these lesions was investigated.

METHODS

Within routine skin cancer screening 45 outpatients with a total of 77 macular melanocytic nevi were prospectively recruited. Deep shave excisions of these lesions were performed with a double-edged razor blade followed by chemical hemostasis. Histologically all specimens were processed and evaluated in a routine manner. After 6 months the physician and patients evaluated the shave sites for cosmetic outcome with a score graded from 1 to 4 (1 = excellent; 2 = good; 3 = moderate; 4 = poor).

RESULTS

Histologically 88% (68 of 77) of the melanocytic lesions were described as completely excised and 60% (46 of 77) were diagnosed as atypical melanocytic nevi; 12% (9 of 77) of the nevi were incompletely excised on the depth. On average, the deep margin of the specimens (n = 77) was 0.5 mm (range 0-1.8 mm) and the lateral margin was 2 mm (range 0.3-8.2 mm). After 6 months 56 shave sites could be reassessed. We observed mild hypopigmentation in 52% (29 of 56), hyperpigmentation in 32% (18 of 56), and erythema in 23% (13 of 56). Recurrent nevi occurred in 13% (7 of 56). The evaluation of the cosmetic outcome by the patients (mean score 1.7) achieved better results than the evaluation by the physician (mean score 2.5). The cosmetic results showed no significant (P >.05) differences in various anatomic sites.

CONCLUSION

Our data confirm that deep razor blade excision presents a highly useful and inexpensive method for the removal of macular melanocytic nevi that yields adequate specimens for pathologic interpretation. We consider that shave excision with the razor blade technique is potentially much less scarring than full-thickness scalpel excisions of nevi. In particular, this is of great significance for patients with multiple nevi, such as dysplastic nevi syndrome.