Actinic keratosis: RCM images accord with histopathology




Reflectance Confocal Microscopy (RCM) images of actinic keratoses (AKs) accord well with histopatholgy images, and trained dermatologists can readily distinguish different grades of cytological atypia in the lesions using RCM images alone, according to a report published in the November issue of Journal of the European Academy of Dermatology and Venereology.

RCM is a noninvasive optical technology that enhances clinical diagnostic accuracy, permitting clinicians to assess cytologic and architectural aspects of the epidermis in vivo. Researchers hypothesized that RCM could be used to grade AKs by allowing clinicians to assess “the irregularity of the honeycombed pattern reflecting the architectural disarray of the epidermal spinous layer,” said Dr. Giovanni Pellacani of the department of dermatology, University of Modena and Reggio Emilia, Modena, Italy, and his associates.

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In a prospective study, two independent pathologists examined micrographs taken from punch biopsies and RCM images from 48 consecutive cases of facial/scalp AKs collected in a database; they also assessed two benign samples from one young patient with no sun-damaged skin and one elderly patient with severely sun-damaged skin, which served as the controls.

They graded the lesions/samples, classifying 38 as low- or moderate-grade AKs, 10 as high-grade AKs, and the two control samples as normal or lowest-grade sun-damaged skin.

Then three “raters” (two dermatopathologists and Dr. Pellacani) evaluated the RCM images, which showed a representative horizontal section of the epidermis at the stratum spinosum, while the two dermatopathologist raters evaluated photomicrographs taken at histopathology examination, grading the keratinocyte atypia they observed.

RCM grading of keratinocyte atypia strongly correlated among the three RCM raters, and the correlations were strongest for higher-grade lesions. Histopathologic grading also strongly correlated between two pathologist raters. Most important, grading of keratinocytic atypia strongly correlated between these two groups: Raters of the RCM images consistently distinguished different grades of atypia accurately.

These findings show that RCM can allow noninvasive in vivo assessment of keratinocyte morphology that is comparable to that obtained with invasive histopathology, the investigators concluded (J Eur Acad Dermatol Venereol. 2015;29[11]: 2216-21).

“RCM enables one to quickly explore several lesions and skin areas, offering a quasi-histological view of the epidermis useful for the study of AKs. This may lead, in the future, to the use of noninvasive technologies, such as RCM, for studying and monitoring of AKs and other diseases characterized by alterations of keratinocyte morphology thus avoiding the burden of invasive biopsies in clinical trials,” Dr. Pellacani and his associates said.

“Other advantages of noninvasive skin assessments are the possibility to evaluate a larger number of lesions and perilesional areas, and to collect dynamic information on quasi-histological changes occurring during the course of the disease, without alteration induced by the healing process following skin biopsy. This may also facilitate the evaluation of the efficacy of the treatments for AK and field cancerization at cellular level of keratinocytes,” they added.

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