Cloudy and starry milia-like cysts: how well do they distinguish seborrheic keratoses from malignant melanomas?

Abstract

Background: Seborrheic keratoses are the most common skin lesions known to contain small white or yellow structures called milia-like cysts (MLCs). Varied appearances can sometimes make it difficult to differentiate benign lesions from malignant lesions such as melanoma, the deadliest form of skin cancer found in humans.

Objective: The purpose of this study was to determine the statistical occurrence of MLCs in benign vs. malignant lesions.

Methods: A medical student with 10 months experience in examining approximately 1000 dermoscopy images and a dermoscopy-naïve observer analysed contact non-polarized dermoscopy images of 221 malignant melanomas and 175 seborrheic keratoses for presence of MLCs.

Results: The observers found two different types of MLCs present: large ones described as cloudy and smaller ones described as starry. Starry MLCs were found to be prevalent in both seborrheic keratoses and melanomas. Cloudy MLCs, however, were found to have 99.1% specificity for seborrheic keratoses among this group of seborrheic keratoses and melanomas.

Conclusion: Cloudy MLCs can be a useful tool for differentiating between seborrheic keratoses and melanomas.

Figure 1

Seborrheic keratosis with a cloudy MLC and multiple starry MLCs.

Figure 2

Seborrheic keratosis with multiple starry MLCs.

Figure 3

Invasive melanoma 0.63 mm thick with multiple starry MLCs, indicating evolution from a congenital naevus.

Figure 4

A lesion that clinically resembled a melanoma (inset); the cloudy MLCs among multiple starry MLCs suggest a seborrheic keratosis, confirmed with histopathology.