Actinic Keratosis and Non-Invasive Diagnostic Techniques: An Update

Abstract

Actinic keratosis represents the earliest manifestation of non-melanoma skin cancer. Because of their risk of progression to invasive squamous cell carcinoma, an earlier diagnosis and treatment are mandatory. Their diagnosis sometimes could represent a challenge even for expert dermatologists. Dermoscopy, confocal laser microscopy and optical coherence tomography could help clinicians in diagnosis.

Keywords: actinic keratosis; confocal laser microscopy; dermoscopy; optical coherence tomography.

Figure 1

Dermoscopy of AKs. (a) Actinic keratosis showing a typical strawberry pattern with scales: erythema, revealing a marked pink-to-red “pseudo-network” surrounding the hair follicles; white-to-yellow surface scale; hair follicle openings filled with yellowish keratotic plugs and/or surrounded by a white halo; (b) Actinic keratosis showing a typical strawberry pattern without scales: erythema, revealing a marked pink-to-red “pseudo-network” surrounding the hair follicles and hair follicle openings filled with yellowish keratotic plugs and/or surrounded by a white halo; (c) Lightly pigmented actinic keratosis with a superficial brown network consisting of brown, curved double lines that surround enlarged, partially confluent, keratotic follicles of various sizes. This pattern is associated with a red pseudo-network and scales.

Figure 2

Confocal laser microscopy of AKs, epidermal layer. (a) Grade 1 AK presents focal areas of atypical honeycombed pattern at the level of the stratum spinosum, intermingled with areas of preserved, typical honeycombed pattern; (b) Grade 2 AK presents a more diffuse keratinocytes’ atypia. Keratinocytes present a marked atypia, with different cell sizes and shapes; (c) Grade 3 AK is characterized by a markedly atypical honeycombed pattern with areas of partial disruption of the normal epidermal layers, defined as a disarranged pattern. Pleomorphic keratinocytes show a wide variability in cellular size and shapes, and irregular intercellular keratinocyte connections are detected. The small brighter particle are lymphocytes which suggests a marked inflammatory infiltrate within the lesion. Scale bar = 50 um.

Figure 3

Optical coherence tomography of AKs. (a) Conventional OCT image showing point of disruption of the stratum corneum (pink arrows) which are typical of AKs; (b) En-face mode of HD-OCT showing mild atipya with superficial disruption, architectural disarray, and cellular polymorphism at the granular and spinous layer; (c) En-face mode of HD-OCT showing a very severe atypical honeycomb pattern and disarranged epidermal pattern due to the presence of dyskeratotic keratinocytes. These cells, are represented by round, bright nucleated cells.