De novo intraepidermal epithelioid melanocytic dysplasia as a marker of the atypical mole phenotype - a clinical and pathological study of 75 patients

Virtual lesion clinic - Evaluation of a teledermatology triage system for referrals for suspected melanoma

INTRODUCTION

The Virtual Lesion Clinic (VLC) of Waitematā District Health Board (WDHB) improves melanoma assessment and treatment using teledermatology. The VLC is reserved for pigmented lesions referred as suspected melanoma from primary care but indeterminate at the initial triage.

OBJECTIVES

To assess the efficacy of the VLC diagnosis of melanoma.

METHODS

A retrospective audit of suspected melanoma referrals (1 January 2012 to 31 December 2016) was conducted. Lesions were referred to the VLC if diagnostic uncertainty remained at the initial triage. VLC patients attended MoleMap imaging centres, a dermatologist reviewed history and images remotely and suggested a diagnosis and management plan. Post VLC provisional diagnosis of melanoma, all lesions subsequently excised were reviewed. A positive predictive value (PPV) was calculated using concordance between VLC diagnosis of melanoma and histopathological diagnosis of melanoma. Number needed to excise (NNE) for melanoma was derived, as well as an invasive to in-situ melanoma ratio (IM:MIS) and false negative rate (FNR).

RESULTS

The VLC received 1874 referrals for 3546 lesions during the 5-year study period. Six hundred and seventy-nine lesions were recommended excision/biopsy or specialist face-to-face assessment, and 504 lesions were subsequently excised. The PPV was 62%, NNE 1.62 and IM:MIS 0.76 for lesions suspected to be melanoma at VLC assessment. The VLC had a melanoma-specific FNR of 7%.

CONCLUSIONS

The VLC is effective in early diagnosis of melanoma with a high positive predictive value, low number needed to excise and low false negative rate amongst lesions referred as suspected melanoma.

Interpretation of the Complex Melanoma Pathology Report

An ambiguous pathologic report can present a clinical dilemma to the treating surgeon. We describe lesions ranging from the potentially benign to the likely malignant. Correctly identifying features associated with higher-risk lesions has proven challenging given the overall good prognosis and low rate of events. An appropriate treatment plan generally requires discussion between the surgeon and an experienced dermatopathologist. When clinically indicated, additional testing may be used to further support or refute a diagnosis of melanoma. The indications for these techniques, the data to support their use, and the strengths and weakness of each are reviewed.

The role of reflectance confocal microscopy in differentiating melanoma in situ from dysplastic nevi with severe atypia: A cross-sectional study

BACKGROUND

Melanoma in situ and dysplastic nevi with severe atypia present overlapping histopathologic features. Reflectance confocal microscopy findings can be integrated with the dermatopathology report to improve differentiation between melanoma and dysplastic nevi with severe atypia.

OBJECTIVE

To compare prevalence of reflectance confocal microscopy findings between melanoma in situ and dysplastic nevi with severe atypia.

METHODS

This retrospective observational study compared reflectance confocal microscopy findings in dermatopathologically diagnosed dysplastic nevi with severe atypia and melanoma in situ, collected between 2007 and 2017 at a private pigmented-lesion clinic. Concordant pathologic diagnosis was defined as unanimous agreement between 3 dermatopathologists who independently reviewed all cases; all other cases were classified as discordant.

RESULTS

The study included 112 lesions, 62 concordant melanomas in situ, 28 concordant dysplastic nevi with severe atypia, and 22 discordant lesions. In comparing reflectance confocal microscopy findings in concordant cases, melanoma in situ showed more frequently than dysplastic nevi with severe atypia the presence of epidermal atypical melanocytes as round cells (19/62 vs 0/28; P < .001) and dendritic cells (50/62 vs 6/28; P < .001), as well as a diffuse distribution of epidermal atypical melanocytes (50/54 vs 3/6; P = .002). In contrast, dysplastic nevi with severe atypia showed the presence of dense melanocytic nests more frequently than melanoma in situ did (15/28 vs 14/62; P = .003).

LIMITATIONS

The study was based on a limited number of lesions originating from a single clinic.

CONCLUSIONS

Reflectance confocal microscopy findings may help differentiate a subset of dysplastic nevi with severe atypia from melanoma in situ.

Atypical Melanocytic Proliferations: A Review of the Literature

BACKGROUND

Ambiguous histopathologic diagnoses represent a challenge for clinicians because of a lack of definitive diagnosis and related uncertainty about management.

OBJECTIVE

To review the literature on atypical melanocytic proliferations and detail synonymous terms, epidemiology, diagnostic work-up, histopathology, treatment, and prognosis.

METHODS

Databases from PubMed and Web of Science were searched for articles related to atypical melanocytic proliferations.

RESULTS

Intraepidermal melanocytic proliferations with features worrisome for possible melanoma in situ (MIS) are generally excised as for MIS. Reported rates of upstaging of such cases to invasive melanoma on review of the excision are very low. Because invasion, lymph node spread, and metastasis can occur in atypical melanocytic lesions with a thick intradermal component, these are often treated as for malignant melanoma.

CONCLUSION

Because the diagnosis dictates treatment, it is incumbent to establish a diagnosis as definitive as possible, obtaining second or third opinions and using ancillary studies when appropriate. When the diagnosis remains uncertain, it is difficult to provide guidelines for treatment. Clinical care decisions for patients with an uncertain diagnosis are best done on a case-by-case basis weighing probabilities of adverse outcomes against potential benefits and risks from various treatment options.

Histopathological diagnosis of small melanocytic lesions suspicious for malignant melanoma

The concern about malignant skin neoplasms leads to the excision of smaller lesions. This study on small melanocytic lesions aims to evaluate the range of possible histopathological diagnoses, describe histopathological aspects, and assess the usefulness of serial histological sections. We performed a cross-sectional descriptive histopathological study examining 76 pigmented skin lesions up to 6 mm in diameter. Histopathological diagnoses included atypical melanocytic nevi (n=38), common melanocytic nevi (n=18), atypical lentiginous melanocytic hyperplasia with architectural features of atypical melanocytic nevi (n=7), lentigo simplex (n=2), and malignant melanoma (n=1). Ten cases were non-diagnostic. Cytological atypia was not an exclusive finding of atypical lesions. Examination of serial sections did not change histopathological impression. Early detection of malignant melanoma is important, but clinical and dermoscopy exams may be leading to the resection of a great number of benign lesions. Strict attention to histopathological criteria results in a large number of non-diagnostic cases.

Morphologic clues and utility of fluorescence in situ hybridization for the diagnosis of nevoid melanoma

BACKGROUND

Nevoid melanomas include melanomas with a low power silhouette similar to melanocytic nevi. However, at higher power magnification, nevoid melanoma may have severe nuclear atypia and dermal mitoses.

METHODS

We performed a clinical, pathological and molecular study on a series of 58 examples of nevoid melanoma, excluding cases with spitzoid morphology.

RESULTS

We identified distinct morphologic patterns: 'classic' nevoid melanoma, superficial spreading melanomas with nevoid invasive melanoma, lentigo maligna with nevoid invasive melanoma and deep penetrating nevus-like nevoid melanoma. Fluorescence in situ hybridization (FISH) was positive in 74% of cases. Copy number gains in 8q24 were common in amelanotic nevoid melanoma. The median follow-up was 28 months (range 140). At last follow-up, 37 patients had no evidence of disease, 3 were alive with metastases and 6 died from metastatic melanoma. Of these six patients who died, four had a sentinel lymph node biopsy (SLNB) performed, which was negative in all four.

CONCLUSIONS

We describe distinct clues to the diagnosis of nevoid melanoma including occult intraepidermal atypia, and expansile nesting resulting in asymmetric silhouette or dermal papillae expansion. We also describe that nevoid melanoma have infrequent SLNB involvement in aggressive cases, and have frequent 8q24 gains rather than 9p21 deletions. Our results suggest that nevoid melanoma are distinct from spitzoid melanomas and should be distinguished.

De novo intraepidermal epithelioid melanocytic dysplasia: an emerging entity

De novo intraepidermal epithelioid melanocytic dysplasia represents a distinctive form of intraepidermal melanocytic dysplasia. Although these lesions are atypical, they are not diagnostic of melanoma. They are considered a part of the atypical mole phenotype and may define a point in the natural course of melanomagenesis.

Melanocytic nevi simulant of melanoma with medicolegal relevance

A group of melanocytic benign nevi are prone to be misdiagnosed as nodular or superficial spreading melanoma. This review illustrates the most frequent forms of these nevi in direct comparison with their malignant morphologic counterparts. The nevi are: hyper-cellular form of common nevus to be distinguished from nevoid melanoma, Spitz nevus (vs spitzoid melanoma), Reed nevus (vs melanoma with features of Reed nevus), cellular atypical blue nevus (vs melanoma on blue nevus), acral nevus (vs acral melanoma), Clark dysplastic nevus (vs superficial spreading melanoma), desmoplastic nevi (vs desmoplastic melanoma), benign proliferative nodules in congenital nevi (vs melanoma on congenital nevi), epithelioid blue nevus (vs animal type melanoma) and regressed nevus (vs regressed melanoma). For each single 'pair' of morphological look-alikes, a specific set of morphological, immunohistochemical and genetic criteria is provided.