Original article
Patterns of nail matrix and bed of longitudinal melanonychia by intraoperative dermatoscopy

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Background

The dermatoscopic examination of the nail plate has been recently introduced for the evaluation of pigmented nail lesions. There is, however, no evidence that this technique improves diagnostic accuracy of in situ melanoma.

Objective

To establish and validate patterns for intraoperative dermatoscopy of the nail matrix.

Methods

Intraoperative nail matrix dermatoscopy was performed in 100 consecutive bands of longitudinal melanonychia that were excised and submitted to histopathologic examination.

Results

We identified 4 dermatoscopic patterns: regular gray pattern (hypermelanosis), regular brown pattern (benign melanocytic hyperplasia), regular brown pattern with globules or blotch (melanocytic nevi), and irregular pattern (melanoma).

Limitations

Nail matrix dermatoscopy is an invasive procedure that can not routinely be performed in all cases of melanonychia.

Conclusion

The patterns described present high sensitivity and specificity for intraoperative differential diagnosis of pigmented nail lesions.

Introduction

Capsule Summary

  • Longitudinal melanonychia (LM) is a diagnostic challenge, as it may represent either a benign lesion or a nail matrix tumor.

  • Dermatoscopic examination of the nail plate does not provide direct analysis of the nail matrix, which is the anatomic origin of the pigmentation.

  • We have recently introduced intraoperative dermatoscopy, which is performed directly on the nail matrix after nail plate avulsion.

  • This study establishes and validates 4 dermatoscopic patterns observed by using intraoperative dermatoscopy on patients with longitudinal melanonychia

Longitudinal melanonychia (LM) describes the pattern of longitudinal brown -black pigmentation of the nail plate. LM is a diagnostic challenge, since it may represent both benign lesions and nail matrix tumors.1 The Hutchinson sign and the ABCDEF rule, described by Levit et al,2 help the clinician in selecting lesions that require excision for pathologic examination.

The dermatoscopic examination of the nail plate has been recently introduced as a useful tool to improve clinical diagnosis.3, 4 Its main limitation is that, in contrast with dermatoscopic examination of the skin, it does not provide direct analysis of the nail matrix, which is the origin of the pigment band. To overcome this problem, we have recently introduced the intraoperative dermatoscopy examination, which is performed directly on the nail matrix and bed after nail plate avulsion.5, 6, 7 This procedure enables a direct visualization of the dermatoscopic patterns of the pigmented lesion. The objective of this study was to establish and validate the dermatoscopic patterns observed with intraoperative dermatoscopy.

Section snippets

Methods

This study was performed on 100 bands of longitudinal melanonychia that were excised at our institution. All lesions were first studied with nail plate dermatoscopy and then evaluated with intraoperative dermatoscopy of the nail matrix after avulsion of the nail plate prior to surgical excision. The study protocol was approved by the Research Ethics Committee of the Universidade Federal de São Paulo.

Dermatoscopic evaluation of the nail plate was performed with both the HEINE Delta 20

Nail plate dermatoscopy

See Table I. The gray pattern was not represented in our series as bands showing this pattern were not excised as they represent benign lesions that do not require histopathologic examination. The brown regular pattern was found in 44 of 85 benign lesions and in 4 of 15 nail melanomas.

The irregular pattern was found in 41 of 85 benign lesions and in 11 of 15 nail melanomas.

The sensitivity and specificity of nail plate dermoscopy were 0.73 and 0.51, respectively.

Intraoperative dermatoscopy

See Table I. The regular gray

Discussion

In the past few years dermatoscopy has become a very important and useful tool to evaluate pigmented skin lesions.11 Nail plate dermatoscopy has been proposed as a useful technique in the evaluation of nail pigmentation.3, 12, 13 Its value in the differential diagnosis of nail melanoma has not been established.6, 14, 15

Our results show that intraoperative dermatoscopy provides useful information for the differential diagnosis of LM. Removing the nail plate is a simple procedure.16 The procedure

References (22)

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  • Cited by (0)

    Funding sources: None.

    Conflicts of interest: None declared.

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