Melanocytes Pattern in the Normal Nail, With Special Reference to Nail Bed Melanocytes

Subungual melanoma: molecular analysis of 31 cases from early stage to invasive melanoma

AIMS

The distinction between the benign subungual melanocytic lesions and an early lesion of subungual melanoma (SUM) remains a diagnostic challenge. We evaluated the routine diagnostic utility of array Comparative Genomic Hybridization (aCGH) to detect whole-genome copy number variations (CNV) as well as targeted next-generation sequencing (NGS) in SUM.

METHODS AND RESULTS

This retrospective study included 20 cases of in situ SUM and 11 cases of invasive SUM. Analysis by aCGH detected common oncogene amplifications in all but one case of invasive SUM (n = 10) and in all cases of in situ SUM with a melanocyte count (MC) >45/mm (n = 4 true positive) and the average number of CNV was 8.5. Thirteen remaining cases of in situ SUM gave false negative results (n = 13), owing to a lack of sufficient melanocytes to analyse (median MC of 35.35; range: 10.16-39.5). Molecular analysis failed in four cases (three in situ SUM and one invasive SUM) due to insufficient amounts of DNA. Across the whole cohort, the sensitivity of aCGH was 52%, but when adjusting the cutoff to MC >45/mm, the sensitivity was 93%. Targeted NGS was less informative than aCGH analyses in our series of SUM.

CONCLUSION

To distinguish malignant from benign lesions, especially in situ SUM versus atypical lentiginous melanocytic proliferations, aCGH analysis should be performed when the MC is above 45 melanocytes per linear millimetre. This pangenomic method can detect oncogene amplifications, as well as a number of CNV >3, which strongly support the diagnosis of malignancy.

Mohs for Melanoma: A Review of MART-1 Frozen Section Interpretation

BACKGROUND

Mohs surgery for melanoma has been performed for many decades, but advances in the use of immunohistochemistry with frozen sections during Mohs surgery have allowed for more accurate, reliable, and efficient margin assessment with improved local control of the disease.

OBJECTIVE

To describe the use of MART-1 in treating melanoma with Mohs surgery and serve as a primer for the Mohs surgeon adding melanoma cases to their repertoire.

MATERIALS AND METHODS

Review of the literature and discussion of experience with Mohs for melanoma.

RESULTS

Practical approach and pitfalls when assessing margins using MART-1 immunohistochemistry during Mohs surgery for the treatment of melanoma.

CONCLUSION

Mohs for melanoma is an expanding field-education of Mohs surgeons and increasing the practice of this technique has the potential to improve patient outcomes.

Malignant melanoma in the hand: current evidence and recommendations

Malignant melanoma is the leading cause of death from skin cancer. In spite of significant advances in the management of melanoma with the advent of sentinel lymph node biopsy (SLNB) and adjuvant oncological therapies, the death rate continues to increase worldwide. Melanoma in the hand poses additional diagnostic and management challenges. Consequently, these tend to present at a later stage and are associated with a poorer prognosis. It is imperative that hand surgeons treat any pigmented hand lesion with suspicion to ensure rapid diagnosis and treatment. This article outlines the presentation of melanoma, and how to investigate suspicious pigmented lesions of the hand and digits. It guides hand surgeons in their approach to melanoma of the hand, outlining the multidisciplinary team approach as well as current standard surgical and reconstructive options to optimize outcomes.

Managing longitudinal melanonychia

Longitudinal melanonychia (LM) is a pigmented band extending from the matrix to the distal edge of a nail. It is caused by increased production of melanin within the matrix, and integration into the nail plate. The origin of this production is usually benign, due to activation, hyperplasia or proliferation of melanocytes normally present in the matrix. In some cases, however, LM is the manifestation of a subungual melanoma, the diagnosis of which must be made early. Biographical, clinical and dermoscopic criteria make it possible to suspect melanoma and decide whether to perform biopsy. None of these criteria, however, are specific and definitive diagnosis requires pathologic examination of a matrix biopsy. The biopsy technique should enable reliable histological study while limiting the risk of secondary nail dystrophy. Initial resection should ideally involve the entire lesion. Complete elevation of the nail plate enables the lesion to be precisely located. Lesions up to 3 mm can be removed by longitudinal resection biopsies without significant sequelae. In more extensive lesions, incision or tangential ("shave") biopsy can be performed without impairing prognosis. In clinical presentations strongly suggestive of melanoma, immediate complete resection of the entire nail unit may be proposed.

Basic Concepts in Nail Pathology

ABSTRACT

Understanding nail pathology is complex for general pathologists and even for those dermatopathologists who do not receive many nail samples in their laboratories. In this article, we attempt to review some of the primary entities in nail pathology with the aid of modern interpretations of nail histology and embryology. We also provide diagrams that can aid in comprehending this field of pathology.

Detection of Morphine and Opioids in Fingernails: Immunohistochemical Analysis and Confirmation with Ultra-High-Performance Liquid Chromatography Coupled with High-Resolution Mass Spectrometry

This study aimed to investigate the detection of morphine in fingernails from forensic autopsies using immunohistochemistry (IHC), with confirmation by ultra-high-performance liquid chromatography coupled with high-resolution mass spectrometry (UHPLC-HRMS). A primary antibody specific to morphine and a secondary antibody conjugated to horseradish peroxidase (HRP) was used. IHC on specimens of Subjects A and B (both drug addicts) resulted in the detection of morphine on a cell layer of the nail plate matrix. UHPLC-HRMS and GC-MS analysis showed that Subject A had a morphine concentration of 0.35 ng/mg in the fingernail and 472 ng/mL in the blood, while Subject B reached 1.23 ng/mg in the fingernail and 360 ng/ml in the blood. Most of those matrices were positive for codeine, methadone, EDDP, and 6-MAM. The use of IHC in Subject C (a former addict) showed no positivity for morphine in the fingernail, while the UHPLC-HRMS analysis confirmed its absence in the fingernail and blood. Additionally, an analysis of the scalp or pubic hair of the subjects was carried out using UHPLC-HRMS. The results suggest that IHC can be used to establish the site of accumulation of morphine in the nail matrix; for postmortem diagnosis; and that basic substances can be detected by UHPLC-HRMS. There are no previous studies on the use of IHC as a technique for forensic purposes in unconventional matrices, such as nails.

Preferentially Expressed Nuclear Antigen in Melanoma Expression in Melanocytic Activation (Melanotic Macule) of the Nail Unit. A Potential Diagnostic Pitfall? A Study of 3 Cases

ABSTRACT

Recent studies have argued that melanocyte preferentially expressed nuclear antigen in melanoma (PRAME) is a sensitive and specific immunohistochemical marker of melanoma, including acral melanoma. In addition, loss of p16 expression has recently been suggested to have diagnostic utility in acral melanocytic tumors. The purpose of this study was to report PRAME expression in 3 cases of melanocytic activation (MAN). There were 2 men and 1 woman ranging in age at diagnosis from 46 years to 78 years (mean 61, 6 years). All cases involved a single digit. One lesion was in the fingernail (fifth finger), whereas the remaining 2 lesions were in the toenails (hallux). All the patient presented with a longitudinal melanonychia. The width of the lesions varied from 3 mm (2 cases) to 4 mm (1 case). The duration of the lesions before diagnosis varied from 12 to 24 months. Distinction of MAN from melanoma in situ is not always easy. Some morphological misleading features are illustrated in this study: (1) the suprabasal location of matrix melanocytes with long and thick dendrites within the 2-4 germinative cell layers; (2) the microconfluence of 2 melanocytes and rare melanocytes with a relatively large nucleus, however in a general context of melanocyte scarcity; and (3) the occasional nonspecific nuclear microphtalmia-associated transcription factor (MITF) staining of keratogeneous cells. Such staining could suggest a pagetoid spread of melanocytes in the keratogenous zone. PRAME antibody revealed a strong and diffuse staining in all cases. In addition, all cases were p16 negative. In this study, the melanocyte count inferior to 9 melanocytes/mm and the lack of nuclear atypia or confluence of melanocytes permitted a confident diagnosis of MAN. Limitations of our study lie largely in the small number of cases. Despite this, the expression of PRAME in some MAN seems to hamper its diagnostic value in differentiating benign from malignant lesion.

Leukonychia: What Can White Nails Tell Us?

Changes in nail color can provide important clues of underlying systemic and skin disease. In particular, white discoloration (leukonychia) has a high prevalence with a wide array of potential relevant causes, from simple manicure habits to life-threatening liver or kidney failure. Therefore, a reliable assessment of the patient with leukonychia is essential. In the past, two classifications for leukonychia have been presented. The morphological classifies the nail according to the distribution of the white lines: total, partial, transversal, and longitudinal leukonychia. Mees’ and Muehrcke’s lines are examples of transversal leukonychia, while Terry’s and Lindsay’s nails are examples of total and partial leukonychia. The anatomical classifies according to the structure responsible for the white color: the nail plate in true leukonychia, the nail bed in apparent leukonychia, and the surface only in pseudoleukonychia. In this review, both morphological and anatomical features have been combined in an algorithm that enables clinicians to approach leukonychia efficiently and effectively.

Subungual Melanocytic Lesions: Key Clinical and Pathologic Concepts and Biopsy Techniques

Both dermatologists and pathologists sometimes find daunting the evaluation of melanonychia (especially subungual melanocytic lesions) because of the fear of performing nail surgery due to the risk of dystrophy, difficulties processing and interpreting nail biopsy specimens, and a general lack of experience in the field. Nevertheless, mastery of nail biopsy techniques, correct processing and orientation of specimens, and familiarity with the histologic particularities of the nail apparatus can attenuate the undoubted complexity and facilitate the tasks involved. Longitudinal excision is the biopsy technique that ensures the simplest histologic interpretation, and it is associated with a low risk of nail dystrophy when performed correctly. Clinical and epidemiological data are crucial. Subungual melanoma in childhood, for instance, is very rare and even lesions with atypical clinical and/or histologic features are probably benign. The presence of suprabasal melanocytes and other findings that would suggest malignancy at other sites are considered normal in the nail apparatus. Subungual melanoma shows a lentiginous pattern in the early stages of disease, and detection of an inflammatory infiltrate accompanying atypical lentiginous subungual lesions would appear to be one of the first diagnostic findings.

Subungual Melanocytic Lesions: Key Clinical and Pathologic Concepts and Biopsy Techniques

Both dermatologists and pathologists sometimes find daunting the evaluation of melanonychia (especially subungual melanocytic lesions) because of the fear of performing nail surgery due to the risk of dystrophy, difficulties processing and interpreting nail biopsy specimens, and a general lack of experience in the field. Nevertheless, mastery of nail biopsy techniques, correct processing and orientation of specimens, and familiarity with the histologic particularities of the nail apparatus can attenuate the undoubted complexity and facilitate the tasks involved. Longitudinal excision is the biopsy technique that ensures the simplest histologic interpretation, and it is associated with a low risk of nail dystrophy when performed correctly. Clinical and epidemiological data are crucial. Subungual melanoma in childhood, for instance, is very rare and even lesions with atypical clinical and/or histologic features are probably benign. The presence of suprabasal melanocytes and other findings that would suggest malignancy at other sites are considered normal in the nail apparatus. Subungual melanoma shows a lentiginous pattern in the early stages of disease, and detection of an inflammatory infiltrate accompanying atypical lentiginous subungual lesions would appear to be one of the first diagnostic findings.

Clinicopathological, immunohistochemical and fluorescence in-situ hybridisation features of early subungual melanoma: an analysis of 65 cases

AIMS

Very limited data are available concerning the clinicopathological and molecular features of early subungual melanoma (SM), especially with regard to the Asian population. The aim of this study was to investigate the clinical, histological, immunohistochemical and chromosomal features of early SM.

METHODS AND RESULTS

Fifty-two in-situ and 13 thin (Breslow thickness ≤1.0 mm) SM cases were retrospectively reviewed. All patients presented with longitudinal melanonychia involving a single digit, and the thumb was the most affected digit (35 of 65, 53.8%). Microscopically, most cases showed small to medium nuclear enlargement (58 of 65) and mild to moderate nuclear atypia (57 of 65). Hyperchromatism and irregular contours of nuclei were persistent features in all cases. The variation of melanocyte count (the number of melanocytes per mm dermal-epithelial junction) ranged from 31 to 255. Intra-epithelial mitoses were identified in 34 cases (52.3%). Statistically, features of in-situ lesions including higher melanocyte count (>70), presence of multinucleated melanocytes, inflammatory infiltrate and cutaneous adnexal extension, were associated with early invasion. Melan-A, human melanoma B (HMB)45, mouse monoclonal melanoma antibody (PNL2) and SOX10 antibodies (>95.0%) showed superior diagnostic sensitivity to S-100 protein (83.1%). Fluorescence in-situ hybridisation (FISH) results were positive in 15 of 23 successfully analysed cases.

CONCLUSIONS

To the best of our knowledge, this is the largest single-institution study of early SM in an Asian population, and the largest cohort tested by FISH. Early SM mainly showed small to medium nuclear enlargement and mild to moderate nuclear atypia. High melanocyte count, hyperchromatism and irregular contours of nuclei and intra-epithelial mitoses are crucial diagnostic parameters. Immunohistochemistry, especially SOX10 staining, and FISH analysis are valuable in the diagnosis of SM.

Blue nevus of the nail: A case report and review

Blue nevus (BN), in all its clinical variants, rarely affects the nail bed. This leads to difficulty in the diagnosis of BN within the nail bed as well as to challenges with regard to its treatment and follow-up management, not solely attributed to the intrinsic difficulty of the anatomical site. We present the first case in the literature of an acquired cellular BN entirely confined within the nail bed, in a female Caucasian patient. We propose diagnostic and therapeutic options based on personal clinical and surgical experience.

Photoonycholysis: new findings

First described in 1961, photoonycholysis (PO) is a rare nail alteration that may result from drug intake, from topical aminolevulinate photodynamic therapy or from photosensitive conditions such as porphyria or pseudoporphyria. Spontaneous PO is rare. This review updates the numerous causes of PO and highlights some new ways producing this condition. Four different types of PO are clearly recognized without relationship with the responsible drug. An updated list of potential inducing drug is provided. Some practical points on PO have been raised. The inability to reproduce photoonycholysis experimentally should be emphasized, and the pathogenesis of PO still needs to be clarified.