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Clinical Size Not Predictive of Invasive Lentigo Maligna

Clinical area does not appear to be predictive of invasion of lentigo maligna (LM), according to the findings of a recent study.

“There are no well-defined clinical factors to predict the risk of occult invasion in [LM] prior to complete histopathologic analysis,” the researchers said. They evaluated whether clinical size was a predictor of invasion in LM and subclinical extension using data from 600 consecutive patients with LM treated at a tertiary cancer center from 2006 to 2019 (mean age, 65.9 years; 62.8% male). All patients were treated with staged excision. Patient and tumor data were collected, and LM clinical area was calculated in square millimeters (length x width).

The researchers found that the mean LM clinical area was 128.32 mm2 for in situ lesions vs 200.14 mm2 for invasive lesions. Based on quantile regression, the median margin required for complete removal increased with LM clinical area, they added. They noted that the study was limited due to possible referral bias and the presentation of more complex cases at their tertiary cancer center.

“LM can present with variable clinical size which may correlate with subclinical extension; however, the presence of invasion is not well estimated by LM clinical area,” the researchers concluded.


Navarrete-Dechent C, Aleissa S, Connolly K, et al. Clinical size is a poor predictor of invasion in melanoma of the lentigo maligna type. J Am Acad Dermatol. Published online October 20, 2020.  doi:10.1016/j.jaad.2020.10.023

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