Early Detection of Subungual Melanoma In Situ: Proposal of ABCD Strategy in Clinical Practice Based on Case Series

Looking Beyond the Hutchinson Sign: A Retrospective Study of Clinical Factors Indicating the Presence and Invasiveness of Nail Unit Melanoma in Patients With Longitudinal Melanonychia

BACKGROUND

The data underlying this article are available in the article.Longitudinal melanonychia (LM) presents a challenge because nail unit melanoma (NUM) must be considered as a differential diagnosis. Because nail matrix biopsy may result in nail dystrophy, it is important to distinguish NUM from LM.

OBJECTIVE

To provide evidence of previously reported clinical factors indicative of NUM in patients with LM.

METHODS

This was a retrospective study of patients who presented with LM and had biopsy-confirmed NUM from 2005 to 2021. Benign LM was either confirmed by biopsy or considered benign if followed without the need for biopsy. Clinical factors associated with LM and NUM were compared by multivariate regression.

RESULTS

A total of 177 patients (97 LM and 80 NUM) were included. Multivariate regression showed that high band color intensity (p = .0031), variegation (p = .0005), nail plate splitting (p = .0017), Hutchinson sign (p = .0027), and band change (p = .001) correlated with malignancy. Nail plate splitting was associated with Breslow thickness.

CONCLUSION

Malignancy should be suspected and biopsy performed in patients with LM and high band color intensity, variegation, nail plate splitting, Hutchinson sign, and band change.

Clinical and dermoscopic findings of benign longitudinal melanonychia due to melanocytic activation differ by skin type and predict likelihood of nail matrix biopsy

BACKGROUND

Longitudinal melanonychia (LM) is a common dermatologic finding in clinical practice with a broad differential diagnosis. Melanocytic activation is the most common LM etiology.

OBJECTIVE

To investigate clinical and dermoscopic differences of benign LM based on Fitzpatrick skin type and in biopsied vs. non-biopsied patients.

METHODS

A 10-year retrospective cohort of 248 benign LM cases at Weill Cornell Dermatology was identified and analyzed.

RESULTS

Darker-skinned vs. lighter-skinned patients had higher band width percentage (p=0.0125), lower band brightness (p<0.001), more band changes (p=0.0071), and received more biopsies (p=0.032). Biopsied (n=47) vs. non-biopsied patients (n=201) had less multidigit band involvement (p=0.0008), higher band width percentage (p=0.0213), lower band brightness (p=0.0003), and more band changes (p<0.0001). Darker skin types more often had brown vs. grey coloration on dermoscopy (p=0.0232). Mean band width percentage for all biopsied patients was 30.81% (range: 5.80%-100%).

LIMITATIONS

Single-center retrospective design. Subungual melanoma and other benign LM etiologies were not analyzed. Only 18.95% of patients received a biopsy.

CONCLUSION

Darker vs. lighter skin types more often present with darker and wider bands, brown vs. grey coloration on dermoscopy, and receive more biopsies. Multi-institutional studies on LM are needed to determine nail matrix biopsy criteria in different skin types.

Cyclin D1 and PRAME expression in distinguishing melanoma in situ from benign melanocytic proliferation of the nail unit

BACKGROUND

Distinguishing benign lesion from early malignancy in melanocytic lesions of the nail unit still remains a diagnostic challenge, both clinically and histopathologically. While several immunohistochemistry (IHC) stainings have been suggested to help discriminate benign subungual melanocytic proliferation (SMP) and subungual melanoma in situ (MIS), the diagnostic utility of IHC staining for cyclin D1 and PRAME has not been thoroughly investigated in melanocytic lesions of nail unit.

METHODS

This retrospective study included cases of benign SMP and subungual MIS confirmed by biopsy at Asan Medical Center from January 2016 to December 2020. Cases of melanocytic activation without proliferation and melanoma where dermal invasion was identified were excluded. Cyclin D1 and PRAME expression was assessed by counting proportion of melanocytes with nuclear positivity under 200x magnification.

RESULTS

A total of 14 patients with benign SMP and 13 patients with subungual MIS were included in this study. 11 patients with benign SMP (71.4%) and 5 patients with subungual MIS (38.5%) showed > 60% nuclear immunostaining for cyclin D1, respectively. While 13 patients with benign SMP (92.9%) showed totally negative staining for PRAME, 10 patients with subungual MIS (76.9%) exhibited > 50% nuclear immunostaining for PRAME. Using the cutoff of 10%, PRAME exhibited good overall discrimination between benign SMP and subungual MIS (AUC = 0.849, 95% CI = 0.659-0.957).

CONCLUSIONS

This study suggests that PRAME IHC staining as a reliable discriminator in distinguishing subungual MIS from benign SMP.

Hutchinson Sign: Biopsy May Assist in Diagnosis of Subungual Melanoma in Situ

BACKGROUND

Early and accurate diagnosis of subungual melanoma (SUM) through histopathologic examination is critical, but lack of clinical suspicion leads to delays in diagnosis. Hutchinson sign (HS) can be one of the important clinical indicators for diagnosing SUM.

OBJECTIVE

To evaluate the diagnostic value of small biopsies of HS for detecting SUM in situ.

METHODS

We retrospectively evaluated 12 patients who were diagnosed as SUM in situ and underwent punch biopsy at HS areas. Clinical features, dermoscopic findings, and histopathologic findings in HS regions were analyzed.

RESULTS

In most cases, HS was seen in hyponychium (11/12, 91.7%) with 1 case found in proximal nail fold, and 1 case in both the hyponychium and proximal nail fold. Dermoscopic features of HS showed irregular diffuse pigmentation (12/12, 100%) and parallel ridge pattern (7/12, 58.3%). Histopathologically, all cases showed irregularly scattered atypical melanocytes with hyperchromatic nuclei. Two cases showed subtle changes in melanocytes with little nuclear atypia, but additional section specimen showed more definitive findings of SUM in situ.

CONCLUSION

We present a supplementary biopsy technique for diagnosing SUM. Biopsy of HS may help in the diagnosis of SUM.

An Evidence-Based Approach to Pediatric Melanonychia

Melanonychia including melanonychia striata in children poses a diagnostic dilemma. Atypical clinical features often raise the possibility of malignancy, and a nail unit biopsy may be recommended. Commensurate with atypical clinical features, the histopathology may also appear alarming. However, accumulating data illustrate that most cases of melanonychia striata are benign and suggest that an alternate approach is often warranted for pediatric patients. Herein, we review the existing data regarding pediatric melanonychia striata and offer an evidence-based approach to its evaluation and management.

Predictor of Subungual Melanoma against Benign Longitudinal Melanonychia: A Retrospective Cohort Study from Korea

Background

Longitudinal melanonychia (LM) is a common clinical finding. Most cases of LM are benign, and a wait-and-see approach is preferred in the management of this condition. Nevertheless, it is important for clinicians to distinguish subungual melanoma (SUM) from other benign LMs.

Objective

To evaluate the demographic and clinicopathologic characteristics of LM in the Korean population and to identify the predictor of SUM against other benign conditions.

Methods

This was a single-center retrospective cohort study including patients who underwent nail biopsy for LM from January 2000 to May 2019. To identify the predictor of SUM, receiver operating characteristic (ROC) analyses was performed.

Results

A total of 68 cases of biopsy-proven LM were included in the analysis. Among the 68 cases, 8 were SUM. In univariable analysis, patients diagnosed with SUM were older (p=0.035) and had a longer disease duration (p=0.004). They also showed multicolor pigmentation of LM (p=0.022), a larger width of LM (p<0.001), and associated nail plate dystrophy (p=0.010) than patients diagnosed with benign conditions. In multivariable logistic regression, width of LM showed statistical significance (odds ratio, 1.083; 95% confidence interval, 1.018~1.153). ROC analysis suggested that an LM width >28% of the whole nail was the predictor of SUM (area under the curve=0.883; p<0.001).

Conclusion

SUM has distinct demographic and clinical features. The width of LM can predict SUM against other benign LMs.

Clinical features of subungual melanoma according to the extent of Hutchinson's nail sign: a retrospective single-centre study

BACKGROUND

Hutchinson's nail sign (HS) is among the diagnostic criteria for subungual melanoma (SUM). However, there is minimal evidence supporting the overall clinical significance of HS in SUM.

OBJECTIVES

To identify clinicopathological features of SUM according to the extent of HS.

METHODS

Retrospective cohort study was performed with consecutive SUM patients at a single centre from January 2006 to December 2017. The extent of HS was defined by the number of affected nail folds (range 0-4). Comparison groups were organized as follows: patients with HS (affecting ≥1 nail folds) vs. without HS; patients with HS affecting ≥2 nail folds vs. HS affecting <2 nail folds; patients with HS affecting ≥3 nail folds vs. HS affecting <3 nail folds. Clinicopathological characteristics of SUM were compared between the groups.

RESULTS

Sixty-one SUM patients were included. Forty-six (75.4%) exhibited HS; 22 (47.8%) on a toe and 24 (52.2%) on a finger. In multivariate analysis, nail destruction [hazard ratio (HR), 10.00; 95% confidence interval (CI), 2.61-38.30; P = 0.001] was significantly associated with the presence of HS and amputation was significantly associated with HS affecting ≥2 nail folds (HR, 4.75; 95% CI, 1.36-16.61; P = 0.015). High T stage (HR, 1.85; 95% CI, 1.20-2.85; P = 0.005, Fig. 2) was significantly associated with HS appearing in ≥3 nail folds.

CONCLUSION

Besides its value of detecting SUM, HS provides useful clinical information. The number of nail folds exhibiting HS could be a useful clinical clue for planning therapeutic strategies for SUM.