Original article
Concordance of handheld reflectance confocal microscopy (RCM) with histopathology in the diagnosis of lentigo maligna (LM): A prospective study

https://doi.org/10.1016/j.jaad.2015.12.045Get rights and content

Background

Reflectance confocal microscopy (RCM) provides real-time noninvasive imaging of cell structure and may be useful in diagnosing lentigo maligna (LM). Few studies have compared performance of RCM with histopathology in diagnosing LM, and specific features influencing RCM interpretation are not well described.

Objective

We sought to determine concordance rate between RCM and histopathology in the evaluation of suspected LM and to identify factors that may obscure diagnosis.

Methods

We designed a prospective study involving 17 participants seen for evaluation at a large tertiary referral center. Cases included primary lesions and possible recurrent and/or previously treated lesions. A total of 63 clinically equivocal sites were assessed by RCM and histopathology.

Results

RCM and histopathology interpretations were concordant in 56 of 63 sites (89%). There were no false-negative and 7 false-positive results using RCM (sensitivity 100%, specificity 71%, positive predictive value 85%, negative predictive value 100%). Features suggestive of LM in the false-positive group included the presence of numerous hyperreflectile large cells at the dermoepidermal junction and follicular localization of these cells.

Limitations

A larger test set is needed to more reliably distinguish LM from benign lesions using RCM and to improve specificity.

Conclusion

RCM shows excellent sensitivity for detecting LM although features of benign macules on a background of actinically damaged skin can obscure diagnosis and limit its specificity.

Section snippets

Study design

We designed a prospective study involving participants being seen in consultation by the dermatology service at Memorial Sloan Kettering Cancer Center in New York, NY. Eligible participants included men and women seen for evaluation of known or suspected LM between August 1, 2014, and August 31, 2015. Cases included primary lesions and possible recurrent and/or previously treated lesions. Both pigmented and amelanotic lesions were included. The study was approved by the Memorial Sloan Kettering

Participant and lesion characteristics

Seventeen participants were included in our study (9 male, 8 female; average age 71 years, range 35-90 years). Ten of the 17 lesions for evaluation occurred on the cheek, 3 on the forehead or scalp, and 1 each on the nose, lip, chin, and neck. The average lesion size was 2.5 cm (range 0.5-11 cm, SD 2.6 cm). Fifteen participants had lesions that were at least LM as determined by histopathology, including 4 participants with LM melanoma. Two participants had lesions that were clinically

Discussion

In this study, we show that RCM demonstrates excellent sensitivity and performed at least as well as conventional histopathology in detecting LM. The achieved sensitivity of 100% included cases of recurrent and/or previously treated lesions, which can be particularly difficult to diagnose clinically because of frequent nonspecific pigmentation or treatment-induced inflammation present in these lesions. Two other groups have previously reported sensitivities of 100% using RCM to detect LM,

References (21)

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Cited by (0)

Supported in part by the Memorial Sloan Kettering Cancer Center Support Grant/Core Grant (P30 CA008748).

Conflicts of interest: None declared.

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